static reflection - Page 103

How to make HTML Helpers that supports generic type?

- by Fleents

public static class EmptyOrNullHelper public static string EmptyOrNull(this HtmlHelper helper, IQueryable(T) type) { //Code } }

How to format given string using regex?

So I have defined variables in such a way in my file: public static final String hello_world = "hello world" public static final String awesome_world = "awesome world" public static final String bye_world= "bye world" I have many declarations like that. Is it possible to format them as(All '=' in a line): public static final String hello_world = "hello world" public static final String awesome_world = "awesome world" public static final String bye_world = "bye world" I can't even think of a way to do it. Any kind of help is appreciated. P.S If it matters, I use sublime text 2.

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Cisco ASA not forwarding traffic from one interface to another

- by Antoine Benkemoun

Hello ServerFault, I am needing help in the configuration process of my Cisco ASA 5510. I have set up 4 Cisco ASA interconnected together via a big LAN. Each Cisco ASA has 3 or 4 LANs attached to them. The IP routing part is taken care of by OSPF. My problem is on another level. A computer connected to one of the LANs attached to an ASA has no problem communicating with the outside world. The outside world being anything "after" the ASA. My problem is that I am completely unable to have them communicate with another LAN connected to the same ASA. To rephrase this, I am unable to send traffic from one interface of a given ASA to another interface of the same ASA. My configuration is the following : ! hostname Fuji ! interface Ethernet0/0 speed 100 duplex full nameif outside security-level 0 ip address 10.0.0.2 255.255.255.0 no shutdown ! interface Ethernet0/1 speed 100 duplex full nameif cs4 no shutdown security-level 100 ip address 10.1.4.1 255.255.255.0 ! interface Ethernet0/2 speed 100 duplex full no shutdown ! interface Ethernet0/2.15 vlan 15 nameif cs5 security-level 100 ip address 10.1.5.1 255.255.255.0 ! interface Ethernet0/2.16 vlan 16 nameif cs6 security-level 100 ip address 10.1.6.1 255.255.255.0 ! interface Management0/0 speed 100 duplex full nameif management security-level 100 ip address 10.6.0.252 255.255.255.0 ! access-list nat_cs4 extended permit ip 10.1.4.0 255.255.255.0 any access-list acl_cs4 extended permit ip 10.1.4.0 255.255.255.0 any access-list nat_cs5 extended permit ip 10.1.5.0 255.255.255.0 any access-list acl_cs5 extended permit ip 10.1.5.0 255.255.255.0 any access-list nat_cs6 extended permit ip 10.1.6.0 255.255.255.0 any access-list acl_cs6 extended permit ip 10.1.6.0 255.255.255.0 any ! access-list nat_outside extended permit ip any any access-list acl_outside extended permit ip any 10.1.4.0 255.255.255.0 access-list acl_outside extended permit ip any 10.1.5.0 255.255.255.0 access-list acl_outside extended permit ip any 10.1.6.0 255.255.255.0 ! nat (outside) 0 access-list nat_outside nat (cs4) 0 access-list nat_cs4 nat (cs5) 0 access-list nat_cs5 nat (cs6) 0 access-list nat_cs6 ! static (outside,cs4) 0.0.0.0 0.0.0.0 netmask 0.0.0.0 static (outside,cs5) 0.0.0.0 0.0.0.0 netmask 0.0.0.0 static (outside,cs6) 0.0.0.0 0.0.0.0 netmask 0.0.0.0 ! static (cs4,outside) 10.1.4.0 10.1.4.0 netmask 255.255.255.0 static (cs4,cs5) 10.1.4.0 10.1.4.0 netmask 255.255.255.0 static (cs4,cs6) 10.1.4.0 10.1.4.0 netmask 255.255.255.0 ! static (cs5,outside) 10.1.5.0 10.1.5.0 netmask 255.255.255.0 static (cs5,cs4) 10.1.5.0 10.1.5.0 netmask 255.255.255.0 static (cs5,cs6) 10.1.5.0 10.1.5.0 netmask 255.255.255.0 ! static (cs6,outside) 10.1.6.0 10.1.6.0 netmask 255.255.255.0 static (cs6,cs4) 10.1.6.0 10.1.6.0 netmask 255.255.255.0 static (cs6,cs5) 10.1.6.0 10.1.6.0 netmask 255.255.255.0 ! access-group acl_outside in interface outside access-group acl_cs4 in interface cs4 access-group acl_cs5 in interface cs5 access-group acl_cs6 in interface cs6 ! router ospf 1 network 10.0.0.0 255.255.255.0 area 1 network 10.1.4.0 255.255.255.0 area 1 network 10.1.5.0 255.255.255.0 area 1 network 10.1.6.0 255.255.255.0 area 1 log-adj-changes ! There is nothing really complicated in this configuration. It just NATs from one interface to another and that's it. I have tried enabling same-security-traffic permit inter-interface but that doesn't help. I therefore must be missing something a little bit more complicated. Does anyone know why I cannot foward traffic from one interface to another ? Thank you in advance for your help, Antoine

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Spritebatch drawing sprite with jagged borders

- by Mutoh

Alright, I've been on the making of a sprite class and a sprite sheet manager, but have come across this problem. Pretty much, the project is acting like so; for example: Let's take this .png image, with a transparent background. Note how it has alpha-transparent pixels around it in the lineart. Now, in the latter link's image, in the left (with CornflowerBlue background) it is shown the image drawn in another project (let's call it "Project1") with a simpler sprite class - there, it works. The right (with Purple background for differentiating) shows it drawn with a different class in "Project2" - where the problem manifests itself. This is the Sprite class of Project1: using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.Graphics; namespace WindowsGame2 { class Sprite { Vector2 pos = new Vector2(0, 0); Texture2D image; Rectangle size; float scale = 1.0f; // --- public float X { get { return pos.X; } set { pos.X = value; } } public float Y { get { return pos.Y; } set { pos.Y = value; } } public float Width { get { return size.Width; } } public float Height { get { return size.Height; } } public float Scale { get { return scale; } set { if (value < 0) value = 0; scale = value; if (image != null) { size.Width = (int)(image.Width * scale); size.Height = (int)(image.Height * scale); } } } // --- public void Load(ContentManager Man, string filename) { image = Man.Load<Texture2D>(filename); size = new Rectangle( 0, 0, (int)(image.Width * scale), (int)(image.Height * scale) ); } public void Become(Texture2D frame) { image = frame; size = new Rectangle( 0, 0, (int)(image.Width * scale), (int)(image.Height * scale) ); } public void Draw(SpriteBatch Desenhista) { // Desenhista.Draw(image, pos, Color.White); Desenhista.Draw( image, pos, new Rectangle( 0, 0, image.Width, image.Height ), Color.White, 0.0f, Vector2.Zero, scale, SpriteEffects.None, 0 ); } } } And this is the code in Project2, a rewritten, pretty much, version of the previous class. In this one I added sprite sheet managing and, in particular, removed Load and Become, to allow for static resources and only actual Sprites to be instantiated. using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.Graphics; namespace Mobby_s_Adventure { // Actually, I might desconsider this, and instead use static AnimationLocation[] and instanciated ID and Frame; // For determining the starting frame of an animation in a sheet and being able to iterate through // the Rectangles vector of the Sheet; class AnimationLocation { public int Location; public int FrameCount; // --- public AnimationLocation(int StartingRow, int StartingColumn, int SheetWidth, int NumberOfFrames) { Location = (StartingRow * SheetWidth) + StartingColumn; FrameCount = NumberOfFrames; } public AnimationLocation(int PositionInSheet, int NumberOfFrames) { Location = PositionInSheet; FrameCount = NumberOfFrames; } public static int CalculatePosition(int StartingRow, int StartingColumn, SheetManager Sheet) { return ((StartingRow * Sheet.Width) + StartingColumn); } } class Sprite { // The general stuff; protected SheetManager Sheet; protected Vector2 Position; public Vector2 Axis; protected Color _Tint; public float Angle; public float Scale; protected SpriteEffects _Effect; // --- // protected AnimationManager Animation; // For managing the animations; protected AnimationLocation[] Animation; public int AnimationID; protected int Frame; // --- // Properties for easy accessing of the position of the sprite; public float X { get { return Position.X; } set { Position.X = Axis.X + value; } } public float Y { get { return Position.Y; } set { Position.Y = Axis.Y + value; } } // --- // Properties for knowing the size of the sprite's frames public float Width { get { return Sheet.FrameWidth * Scale; } } public float Height { get { return Sheet.FrameHeight * Scale; } } // --- // Properties for more stuff; public Color Tint { set { _Tint = value; } } public SpriteEffects Effect { set { _Effect = value; } } public int FrameID { get { return Frame; } set { if (value >= (Animation[AnimationID].FrameCount)) value = 0; Frame = value; } } // --- // The only things that will be constantly modified will be AnimationID and FrameID, anything else only // occasionally; public Sprite(SheetManager SpriteSheet, AnimationLocation[] Animations, Vector2 Location, Nullable<Vector2> Origin = null) { // Assign the sprite's sprite sheet; // (Passed by reference! To allow STATIC sheets!) Sheet = SpriteSheet; // Define the animations that the sprite has available; // (Passed by reference! To allow STATIC animation boundaries!) Animation = Animations; // Defaulting some numerical values; Angle = 0.0f; Scale = 1.0f; _Tint = Color.White; _Effect = SpriteEffects.None; // If the user wants a default Axis, it is set in the middle of the frame; if (Origin != null) Axis = Origin.Value; else Axis = new Vector2( Sheet.FrameWidth / 2, Sheet.FrameHeight / 2 ); // Now that we have the axis, we can set the position with no worries; X = Location.X; Y = Location.Y; } // Simply put, draw the sprite with all its characteristics; public void Draw(SpriteBatch Drafter) { Drafter.Draw( Sheet.Texture, Position, Sheet.Rectangles[Animation[AnimationID].Location + FrameID], // Find the rectangle which frames the wanted image; _Tint, Angle, Axis, Scale, _Effect, 0.0f ); } } } And, in any case, this is the SheetManager class found in the previous code: using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.Graphics; namespace Mobby_s_Adventure { class SheetManager { protected Texture2D SpriteSheet; // For storing the sprite sheet; // Number of rows and frames in each row in the SpriteSheet; protected int NumberOfRows; protected int NumberOfColumns; // Size of a single frame; protected int _FrameWidth; protected int _FrameHeight; public Rectangle[] Rectangles; // For storing each frame; // --- public int Width { get { return NumberOfColumns; } } public int Height { get { return NumberOfRows; } } // --- public int FrameWidth { get { return _FrameWidth; } } public int FrameHeight { get { return _FrameHeight; } } // --- public Texture2D Texture { get { return SpriteSheet; } } // --- public SheetManager (Texture2D Texture, int Rows, int FramesInEachRow) { // Normal assigning SpriteSheet = Texture; NumberOfRows = Rows; NumberOfColumns = FramesInEachRow; _FrameHeight = Texture.Height / NumberOfRows; _FrameWidth = Texture.Width / NumberOfColumns; // Framing everything Rectangles = new Rectangle[NumberOfRows * NumberOfColumns]; int ID = 0; for (int i = 0; i < NumberOfRows; i++) { for (int j = 0; j < NumberOfColumns; j++) { Rectangles[ID] = new Rectangle ( _FrameWidth * j, _FrameHeight * i, _FrameWidth, _FrameHeight ); ID++; } } } public SheetManager (Texture2D Texture, int NumberOfFrames): this(Texture, 1, NumberOfFrames) { } } } For even more comprehending, if needed, here is how the main code looks like (it's just messing with the class' capacities, nothing actually; the result is a disembodied feet walking in place animation on the top-left of the screen and a static axe nearby): using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; using System.Threading; namespace Mobby_s_Adventure { /// <summary> /// This is the main type for your game /// </summary> public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; static List<Sprite> ToDraw; static Texture2D AxeSheet; static Texture2D FeetSheet; static SheetManager Axe; static Sprite Jojora; static AnimationLocation[] Hack = new AnimationLocation[1]; static SheetManager Feet; static Sprite Mutoh; static AnimationLocation[] FeetAnimations = new AnimationLocation[2]; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; this.TargetElapsedTime = TimeSpan.FromMilliseconds(100); this.IsFixedTimeStep = true; } /// <summary> /// Allows the game to perform any initialization it needs to before starting to run. /// This is where it can query for any required services and load any non-graphic /// related content. Calling base.Initialize will enumerate through any components /// and initialize them as well. /// </summary> protected override void Initialize() { // TODO: Add your initialization logic here base.Initialize(); } /// <summary> /// LoadContent will be called once per game and is the place to load /// all of your content. /// </summary> protected override void LoadContent() { // Create a new SpriteBatch, which can be used to draw textures. spriteBatch = new SpriteBatch(GraphicsDevice); // Loading logic ToDraw = new List<Sprite>(); AxeSheet = Content.Load<Texture2D>("Sheet"); FeetSheet = Content.Load<Texture2D>("Feet Sheet"); Axe = new SheetManager(AxeSheet, 1); Hack[0] = new AnimationLocation(0, 1); Jojora = new Sprite(Axe, Hack, new Vector2(100, 100), new Vector2(5, 55)); Jojora.AnimationID = 0; Jojora.FrameID = 0; Feet = new SheetManager(FeetSheet, 8); FeetAnimations[0] = new AnimationLocation(1, 7); FeetAnimations[1] = new AnimationLocation(0, 1); Mutoh = new Sprite(Feet, FeetAnimations, new Vector2(0, 0)); Mutoh.AnimationID = 0; Mutoh.FrameID = 0; } /// <summary> /// UnloadContent will be called once per game and is the place to unload /// all content. /// </summary> protected override void UnloadContent() { // TODO: Unload any non ContentManager content here } /// <summary> /// Allows the game to run logic such as updating the world, /// checking for collisions, gathering input, and playing audio. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Update(GameTime gameTime) { // Allows the game to exit if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed) this.Exit(); // Update logic Mutoh.FrameID++; ToDraw.Add(Mutoh); ToDraw.Add(Jojora); base.Update(gameTime); } /// <summary> /// This is called when the game should draw itself. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.Purple); // Drawing logic spriteBatch.Begin(); foreach (Sprite Element in ToDraw) { Element.Draw(spriteBatch); } spriteBatch.Draw(Content.Load<Texture2D>("Sheet"), new Rectangle(50, 50, 55, 60), Color.White); spriteBatch.End(); base.Draw(gameTime); } } } Please help me find out what I'm overlooking! One thing that I have noticed and could aid is that, if inserted the equivalent of this code spriteBatch.Draw( Content.Load<Texture2D>("Image Location"), new Rectangle(X, Y, images width, height), Color.White ); in Project2's Draw(GameTime) of the main loop, it works. EDIT Ok, even if the matter remains unsolved, I have made some more progress! As you see, I managed to get the two kinds of rendering in the same project (the aforementioned Project2, with the more complex Sprite class). This was achieved by adding the following code to Draw(GameTime): protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.Purple); // Drawing logic spriteBatch.Begin(); foreach (Sprite Element in ToDraw) { Element.Draw(spriteBatch); } // Starting here spriteBatch.Draw( Axe.Texture, new Vector2(65, 100), new Rectangle ( 0, 0, Axe.FrameWidth, Axe.FrameHeight ), Color.White, 0.0f, new Vector2(0, 0), 1.0f, SpriteEffects.None, 0.0f ); // Ending here spriteBatch.End(); base.Draw(gameTime); } (Supposing that Axe is the SheetManager containing the texture, sorry if the "jargons" of my code confuse you :s) Thus, I have noticed that the problem is within the Sprite class. But I only get more clueless, because even after modifying its Draw function to this: public void Draw(SpriteBatch Drafter) { /*Drafter.Draw( Sheet.Texture, Position, Sheet.Rectangles[Animation[AnimationID].Location + FrameID], // Find the rectangle which frames the wanted image; _Tint, Angle, Axis, Scale, _Effect, 0.0f );*/ Drafter.Draw( Sheet.Texture, Position, new Rectangle( 0, 0, Sheet.FrameWidth, Sheet.FrameHeight ), Color.White, 0.0f, Vector2.Zero, Scale, SpriteEffects.None, 0 ); } to make it as simple as the patch of code that works, it still draws the sprite jaggedly!

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New Development Snapshot

I've integrated OpenJDK 6 b18. If you're building IKVM from source, you need to download openjdk6-b18-stripped.zip. Changes: Integrated OpenJDK 6 b18. Fixed IKVM.Reflection bug in version number handling (for version parts 32K). Added support for generic parameter custom attributes to IKVM.Reflection (this is missing from June 2006 ECMA CLI spec). Fixed IKVM.Reflection Type.FullName bug. Nested types can also have a namespace...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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How does gluLookAt work?

- by Chan

From my understanding, gluLookAt( eye_x, eye_y, eye_z, center_x, center_y, center_z, up_x, up_y, up_z ); is equivalent to: glRotatef(B, 0.0, 0.0, 1.0); glRotatef(A, wx, wy, wz); glTranslatef(-eye_x, -eye_y, -eye_z); But when I print out the ModelView matrix, the call to glTranslatef() doesn't seem to work properly. Here is the code snippet: #include <stdlib.h> #include <stdio.h> #include <GL/glut.h> #include <iomanip> #include <iostream> #include <string> using namespace std; static const int Rx = 0; static const int Ry = 1; static const int Rz = 2; static const int Ux = 4; static const int Uy = 5; static const int Uz = 6; static const int Ax = 8; static const int Ay = 9; static const int Az = 10; static const int Tx = 12; static const int Ty = 13; static const int Tz = 14; void init() { glClearColor(0.0, 0.0, 0.0, 0.0); glEnable(GL_DEPTH_TEST); glShadeModel(GL_SMOOTH); glEnable(GL_LIGHTING); glEnable(GL_LIGHT0); GLfloat lmodel_ambient[] = { 0.8, 0.0, 0.0, 0.0 }; glLightModelfv(GL_LIGHT_MODEL_AMBIENT, lmodel_ambient); } void displayModelviewMatrix(float MV[16]) { int SPACING = 12; cout << left; cout << "\tMODELVIEW MATRIX\n"; cout << "--------------------------------------------------" << endl; cout << setw(SPACING) << "R" << setw(SPACING) << "U" << setw(SPACING) << "A" << setw(SPACING) << "T" << endl; cout << "--------------------------------------------------" << endl; cout << setw(SPACING) << MV[Rx] << setw(SPACING) << MV[Ux] << setw(SPACING) << MV[Ax] << setw(SPACING) << MV[Tx] << endl; cout << setw(SPACING) << MV[Ry] << setw(SPACING) << MV[Uy] << setw(SPACING) << MV[Ay] << setw(SPACING) << MV[Ty] << endl; cout << setw(SPACING) << MV[Rz] << setw(SPACING) << MV[Uz] << setw(SPACING) << MV[Az] << setw(SPACING) << MV[Tz] << endl; cout << setw(SPACING) << MV[3] << setw(SPACING) << MV[7] << setw(SPACING) << MV[11] << setw(SPACING) << MV[15] << endl; cout << "--------------------------------------------------" << endl; cout << endl; } void reshape(int w, int h) { float ratio = static_cast<float>(w)/h; glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0, ratio, 1.0, 425.0); } void draw() { float m[16]; glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glGetFloatv(GL_MODELVIEW_MATRIX, m); gluLookAt( 300.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f ); glColor3f(1.0, 0.0, 0.0); glutSolidCube(100.0); glGetFloatv(GL_MODELVIEW_MATRIX, m); displayModelviewMatrix(m); glutSwapBuffers(); } int main(int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize(400, 400); glutInitWindowPosition(100, 100); glutCreateWindow("Demo"); glutReshapeFunc(reshape); glutDisplayFunc(draw); init(); glutMainLoop(); return 0; } No matter what value I use for the eye vector: 300, 0, 0 or 0, 300, 0 or 0, 0, 300 the translation vector is the same, which doesn't make any sense because the order of code is in backward order so glTranslatef should run first, then the 2 rotations. Plus, the rotation matrix, is completely independent of the translation column (in the ModelView matrix), then what would cause this weird behavior? Here is the output with the eye vector is (0.0f, 300.0f, 0.0f) MODELVIEW MATRIX -------------------------------------------------- R U A T -------------------------------------------------- 0 0 0 0 0 0 0 0 0 1 0 -300 0 0 0 1 -------------------------------------------------- I would expect the T column to be (0, -300, 0)! So could anyone help me explain this? The implementation of gluLookAt from http://www.mesa3d.org void GLAPIENTRY gluLookAt(GLdouble eyex, GLdouble eyey, GLdouble eyez, GLdouble centerx, GLdouble centery, GLdouble centerz, GLdouble upx, GLdouble upy, GLdouble upz) { float forward[3], side[3], up[3]; GLfloat m[4][4]; forward[0] = centerx - eyex; forward[1] = centery - eyey; forward[2] = centerz - eyez; up[0] = upx; up[1] = upy; up[2] = upz; normalize(forward); /* Side = forward x up */ cross(forward, up, side); normalize(side); /* Recompute up as: up = side x forward */ cross(side, forward, up); __gluMakeIdentityf(&m[0][0]); m[0][0] = side[0]; m[1][0] = side[1]; m[2][0] = side[2]; m[0][1] = up[0]; m[1][1] = up[1]; m[2][1] = up[2]; m[0][2] = -forward[0]; m[1][2] = -forward[1]; m[2][2] = -forward[2]; glMultMatrixf(&m[0][0]); glTranslated(-eyex, -eyey, -eyez); }

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A solution for a PHP website without a framework

- by lortabac

One of our customers asked us to add some dynamic functionality to an existent website, made of several static HTML pages. We normally work with an MVC framework (mostly CodeIgniter), but in this case moving everything to a framework would require too much time. Since it is not a big project, not having the full functionality of a framework is not a problem. But the question is how to keep code clean. The solution I came up with is to divide code in libraries (the application's API) and models. So inside HTML there will only be API calls, and readability will not be sacrificed. I implemented this with a sort of static Registry (sorry if I'm wrong, I am not a design pattern expert): <?php class Custom_framework { //Global database instance private static $db; //Registered models private static $models = array(); //Registered libraries private static $libraries = array(); //Returns a database class instance static public function get_db(){ if(isset(self::$db)){ //If instance exists, returns it return self::$db; } else { //If instance doesn't exists, creates it self::$db = new DB; return self::$db; } } //Returns a model instance static public function get_model($model_name){ if(isset(self::$models[$model_name])){ //If instance exists, returns it return self::$models[$model_name]; } else { //If instance doesn't exists, creates it if(is_file(ROOT_DIR . 'application/models/' . $model_name . '.php')){ include_once ROOT_DIR . 'application/models/' . $model_name . '.php'; self::$models[$model_name] = new $model_name; return self::$models[$model_name]; } else { return FALSE; } } } //Returns a library instance static public function get_library($library_name){ if(isset(self::$libraries[$library_name])){ //If instance exists, returns it return self::$libraries[$library_name]; } else { //If instance doesn't exists, creates it if(is_file(ROOT_DIR . 'application/libraries/' . $library_name . '.php')){ include_once ROOT_DIR . 'application/libraries/' . $library_name . '.php'; self::$libraries[$library_name] = new $library_name; return self::$libraries[$library_name]; } else { return FALSE; } } } } Inside HTML, API methods are accessed like this: <?php echo Custom_framework::get_library('My_library')->my_method(); ?> It looks to me as a practical solution. But I wonder what its drawbacks are, and what the possible alternatives.

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how to clear stack after stack overflow signal occur

- by user353573

In pthread, After reaching yellow zone in stack, signal handler stop the recursive function by making it return however, we can only continue to use extra area in yellow zone, how to clear the rubbish before the yellow zone in the thread stack ? (Copied from "answers"): #include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <signal.h> #include <setjmp.h> #include <sys/mman.h> #include <unistd.h> #include <assert.h> #include <sys/resource.h> #define ALT_STACK_SIZE (64*1024) #define YELLOW_ZONE_PAGES (1) typedef struct { size_t stack_size; char* stack_pointer; char* red_zone_boundary; char* yellow_zone_boundary; sigjmp_buf return_point; size_t red_zone_size; } ThreadInfo; static pthread_key_t thread_info_key; static struct sigaction newAct, oldAct; bool gofromyellow = false; int call_times = 0; static void main_routine(){ // make it overflow if(gofromyellow == true) { printf("return from yellow zone, called %d times\n", call_times); return; } else { call_times = call_times + 1; main_routine(); gofromyellow = true; } } // red zone management static void stackoverflow_routine(){ fprintf(stderr, "stack overflow error.\n"); fflush(stderr); } // yellow zone management static void yellow_zone_hook(){ fprintf(stderr, "exceed yellow zone.\n"); fflush(stderr); } static int get_stack_info(void** stackaddr, size_t* stacksize){ int ret = -1; pthread_attr_t attr; pthread_attr_init(&attr); if(pthread_getattr_np(pthread_self(), &attr) == 0){ ret = pthread_attr_getstack(&attr, stackaddr, stacksize); } pthread_attr_destroy(&attr); return ret; } static int is_in_stack(const ThreadInfo* tinfo, char* pointer){ return (tinfo->stack_pointer <= pointer) && (pointer < tinfo->stack_pointer + tinfo->stack_size); } static int is_in_red_zone(const ThreadInfo* tinfo, char* pointer){ if(tinfo->red_zone_boundary){ return (tinfo->stack_pointer <= pointer) && (pointer < tinfo->red_zone_boundary); } } static int is_in_yellow_zone(const ThreadInfo* tinfo, char* pointer){ if(tinfo->yellow_zone_boundary){ return (tinfo->red_zone_boundary <= pointer) && (pointer < tinfo->yellow_zone_boundary); } } static void set_yellow_zone(ThreadInfo* tinfo){ int pagesize = sysconf(_SC_PAGE_SIZE); assert(pagesize > 0); tinfo->yellow_zone_boundary = tinfo->red_zone_boundary + pagesize * YELLOW_ZONE_PAGES; mprotect(tinfo->red_zone_boundary, pagesize * YELLOW_ZONE_PAGES, PROT_NONE); } static void reset_yellow_zone(ThreadInfo* tinfo){ size_t pagesize = tinfo->yellow_zone_boundary - tinfo->red_zone_boundary; if(mmap(tinfo->red_zone_boundary, pagesize, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0) == 0){ perror("mmap failed"), exit(1); } mprotect(tinfo->red_zone_boundary, pagesize, PROT_READ | PROT_WRITE); tinfo->yellow_zone_boundary = 0; } static void signal_handler(int sig, siginfo_t* sig_info, void* sig_data){ if(sig == SIGSEGV){ ThreadInfo* tinfo = (ThreadInfo*) pthread_getspecific(thread_info_key); char* fault_address = (char*) sig_info->si_addr; if(is_in_stack(tinfo, fault_address)){ if(is_in_red_zone(tinfo, fault_address)){ siglongjmp(tinfo->return_point, 1); }else if(is_in_yellow_zone(tinfo, fault_address)){ reset_yellow_zone(tinfo); yellow_zone_hook(); gofromyellow = true; return; } else { //inside stack not related overflow SEGV happen } } } } static void register_application_info(){ pthread_key_create(&thread_info_key, NULL); sigemptyset(&newAct.sa_mask); sigaddset(&newAct.sa_mask, SIGSEGV); newAct.sa_sigaction = signal_handler; newAct.sa_flags = SA_SIGINFO | SA_RESTART | SA_ONSTACK; sigaction(SIGSEGV, &newAct, &oldAct); } static void register_thread_info(ThreadInfo* tinfo){ stack_t ss; pthread_setspecific(thread_info_key, tinfo); get_stack_info((void**)&tinfo->stack_pointer, &tinfo->stack_size); printf("stack size %d mb\n", tinfo->stack_size/1024/1024 ); tinfo->red_zone_boundary = tinfo->stack_pointer + tinfo->red_zone_size; set_yellow_zone(tinfo); ss.ss_sp = (char*)malloc(ALT_STACK_SIZE); ss.ss_size = ALT_STACK_SIZE; ss.ss_flags = 0; sigaltstack(&ss, NULL); } static void* thread_routine(void* p){ ThreadInfo* tinfo = (ThreadInfo*)p; register_thread_info(tinfo); if(sigsetjmp(tinfo->return_point, 1) == 0){ main_routine(); } else { stackoverflow_routine(); } free(tinfo); printf("after tinfo, end thread\n"); return 0; } int main(int argc, char** argv){ register_application_info(); if( argc == 2 ){ int stacksize = atoi(argv[1]); pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setstacksize(&attr, 1024 * 1024 * stacksize); { pthread_t pid0; ThreadInfo* tinfo = (ThreadInfo*)calloc(1, sizeof(ThreadInfo)); pthread_attr_getguardsize(&attr, &tinfo->red_zone_size); pthread_create(&pid0, &attr, thread_routine, tinfo); pthread_join(pid0, NULL); } } else { printf("Usage: %s stacksize(mb)\n", argv[0]); } return 0; } C language in linux, ubuntu

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Error when call 'qb.query(db, projection, selection, selectionArgs, null, null, orderBy);'

- by smalltalk1960s

Hi all, I make a content provider named 'DictionaryProvider' (Based on NotepadProvider). When my program run to command 'qb.query(db, projection, selection, selectionArgs, null, null, orderBy);', error happen. I don't know how to fix. please help me. Below is my code // file main calling DictionnaryProvider @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.dictionary); final String[] PROJECTION = new String[] { DicColumns._ID, // 0 DicColumns.KEY_WORD, // 1 DicColumns.KEY_DEFINITION // 2 }; Cursor c = managedQuery(DicColumns.CONTENT_URI, PROJECTION, null, null, DicColumns.DEFAULT_SORT_ORDER); String str = ""; if (c.moveToFirst()) { int wordColumn = c.getColumnIndex("KEY_WORD"); int defColumn = c.getColumnIndex("KEY_DEFINITION"); do { // Get the field values str = ""; str += c.getString(wordColumn); str +="\n"; str +=c.getString(defColumn); } while (c.moveToNext()); } Toast.makeText(this, str, Toast.LENGTH_SHORT).show(); } // file DictionaryProvider.java package com.example.helloandroid; import java.util.HashMap; import android.content.ContentProvider; import android.content.ContentValues; import android.content.UriMatcher; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteQueryBuilder; import android.net.Uri; import android.text.TextUtils; import com.example.helloandroid.Dictionary.DicColumns; public class DictionaryProvider extends ContentProvider { //private static final String TAG = "DictionaryProvider"; private DictionaryOpenHelper dbdic; static final int DATABASE_VERSION = 1; static final String DICTIONARY_DATABASE_NAME = "dictionarydb"; static final String DICTIONARY_TABLE_NAME = "dictionary"; private static final UriMatcher sUriMatcher; private static HashMap<String, String> sDicProjectionMap; @Override public int delete(Uri arg0, String arg1, String[] arg2) { // TODO Auto-generated method stub return 0; } @Override public String getType(Uri arg0) { // TODO Auto-generated method stub return null; } @Override public Uri insert(Uri arg0, ContentValues arg1) { // TODO Auto-generated method stub return null; } @Override public boolean onCreate() { // TODO Auto-generated method stub dbdic = new DictionaryOpenHelper(getContext(), DICTIONARY_DATABASE_NAME, null, DATABASE_VERSION); return true; } @Override public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) { SQLiteQueryBuilder qb = new SQLiteQueryBuilder(); qb.setTables(DICTIONARY_TABLE_NAME); switch (sUriMatcher.match(uri)) { case 1: qb.setProjectionMap(sDicProjectionMap); break; case 2: qb.setProjectionMap(sDicProjectionMap); qb.appendWhere(DicColumns._ID + "=" + uri.getPathSegments().get(1)); break; default: throw new IllegalArgumentException("Unknown URI " + uri); } // If no sort order is specified use the default String orderBy; if (TextUtils.isEmpty(sortOrder)) { orderBy = DicColumns.DEFAULT_SORT_ORDER; } else { orderBy = sortOrder; } // Get the database and run the query SQLiteDatabase db = dbdic.getReadableDatabase(); Cursor c = qb.query(db, projection, selection, selectionArgs, null, null, orderBy); // Tell the cursor what uri to watch, so it knows when its source data changes c.setNotificationUri(getContext().getContentResolver(), uri); return c; } @Override public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) { // TODO Auto-generated method stub return 0; } static { sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH); sUriMatcher.addURI(Dictionary.AUTHORITY, "dictionary", 1); sUriMatcher.addURI(Dictionary.AUTHORITY, "dictionary/#", 2); sDicProjectionMap = new HashMap<String, String>(); sDicProjectionMap.put(DicColumns._ID, DicColumns._ID); sDicProjectionMap.put(DicColumns.KEY_WORD, DicColumns.KEY_WORD); sDicProjectionMap.put(DicColumns.KEY_DEFINITION, DicColumns.KEY_DEFINITION); // Support for Live Folders. /*sLiveFolderProjectionMap = new HashMap<String, String>(); sLiveFolderProjectionMap.put(LiveFolders._ID, NoteColumns._ID + " AS " + LiveFolders._ID); sLiveFolderProjectionMap.put(LiveFolders.NAME, NoteColumns.TITLE + " AS " + LiveFolders.NAME);*/ // Add more columns here for more robust Live Folders. } } // file Dictionary.java package com.example.helloandroid; import android.net.Uri; import android.provider.BaseColumns; /** * Convenience definitions for DictionaryProvider */ public final class Dictionary { public static final String AUTHORITY = "com.example.helloandroid.provider.Dictionary"; // This class cannot be instantiated private Dictionary() {} /** * Dictionary table */ public static final class DicColumns implements BaseColumns { // This class cannot be instantiated private DicColumns() {} /** * The content:// style URL for this table */ public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY + "/dictionary"); /** * The MIME type of {@link #CONTENT_URI} providing a directory of notes. */ //public static final String CONTENT_TYPE = "vnd.android.cursor.dir/vnd.google.note"; /** * The MIME type of a {@link #CONTENT_URI} sub-directory of a single note. */ //public static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/vnd.google.note"; /** * The default sort order for this table */ public static final String DEFAULT_SORT_ORDER = "modified DESC"; /** * The key_word of the dictionary * <P>Type: TEXT</P> */ public static final String KEY_WORD = "KEY_WORD"; /** * The key_definition of word * <P>Type: TEXT</P> */ public static final String KEY_DEFINITION = "KEY_DEFINITION"; } } thanks so much

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I am currently serving my static files in Django. How do I use Apache2 to do this?

- by alex

(r'^media/(?P<path>.*)$', 'django.views.static.serve',{'document_root': settings.MEDIA_ROOT}), As you can see, I have a directory called "media" under my Django project. I would like to delete this line in my urls.py and instead us Apache to serve my static files. What do I do to my Apache configs (which files do I change) in order to do this? By the way, I installed Apache2 like normal: sudo aptitude install apache2

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What’s New in ASP.NET 4.0 Part Two: WebForms and Visual Studio Enhancements

- by Rick Strahl

In the last installment I talked about the core changes in the ASP.NET runtime that I’ve been taking advantage of. In this column, I’ll cover the changes to the Web Forms engine and some of the cool improvements in Visual Studio that make Web and general development easier. WebForms The WebForms engine is the area that has received most significant changes in ASP.NET 4.0. Probably the most widely anticipated features are related to managing page client ids and of ViewState on WebForm pages. Take Control of Your ClientIDs Unique ClientID generation in ASP.NET has been one of the most complained about “features” in ASP.NET. Although there’s a very good technical reason for these unique generated ids - they guarantee unique ids for each and every server control on a page - these unique and generated ids often get in the way of client-side JavaScript development and CSS styling as it’s often inconvenient and fragile to work with the long, generated ClientIDs. In ASP.NET 4.0 you can now specify an explicit client id mode on each control or each naming container parent control to control how client ids are generated. By default, ASP.NET generates mangled client ids for any control contained in a naming container (like a Master Page, or a User Control for example). The key to ClientID management in ASP.NET 4.0 are the new ClientIDMode and ClientIDRowSuffix properties. ClientIDMode supports four different ClientID generation settings shown below. For the following examples, imagine that you have a Textbox control named txtName inside of a master page control container on a WebForms page. <%@Page Language="C#" MasterPageFile="~/Site.Master" CodeBehind="WebForm2.aspx.cs" Inherits="WebApplication1.WebForm2" %> <asp:Content ID="content" ContentPlaceHolderID="content" runat="server" ClientIDMode="Static" > <asp:TextBox runat="server" ID="txtName" /> </asp:Content> The four available ClientIDMode values are: AutoID This is the existing behavior in ASP.NET 1.x-3.x where full naming container munging takes place. <input name="ctl00$content$txtName" type="text" id="ctl00_content_txtName" /> This should be familiar to any ASP.NET developer and results in fairly unpredictable client ids that can easily change if the containership hierarchy changes. For example, removing the master page changes the name in this case, so if you were to move a block of script code that works against the control to a non-Master page, the script code immediately breaks. Static This option is the most deterministic setting that forces the control’s ClientID to use its ID value directly. No naming container naming at all is applied and you end up with clean client ids: <input name="ctl00$content$txtName" type="text" id="txtName" /> Note that the name property which is used for postback variables to the server still is munged, but the ClientID property is displayed simply as the ID value that you have assigned to the control. This option is what most of us want to use, but you have to be clear on that because it can potentially cause conflicts with other controls on the page. If there are several instances of the same naming container (several instances of the same user control for example) there can easily be a client id naming conflict. Note that if you assign Static to a data-bound control, like a list child control in templates, you do not get unique ids either, so for list controls where you rely on unique id for child controls, you’ll probably want to use Predictable rather than Static. I’ll write more on this a little later when I discuss ClientIDRowSuffix. Predictable The previous two values are pretty self-explanatory. Predictable however, requires some explanation. To me at least it’s not in the least bit predictable. MSDN defines this value as follows: This algorithm is used for controls that are in data-bound controls. The ClientID value is generated by concatenating the ClientID value of the parent naming container with the ID value of the control. If the control is a data-bound control that generates multiple rows, the value of the data field specified in the ClientIDRowSuffix property is added at the end. For the GridView control, multiple data fields can be specified. If the ClientIDRowSuffix property is blank, a sequential number is added at the end instead of a data-field value. Each segment is separated by an underscore character (_). The key that makes this value a bit confusing is that it relies on the parent NamingContainer’s ClientID to build its own ClientID value. This effectively means that the value is not predictable at all but rather very tightly coupled to the parent naming container’s ClientIDMode setting. For my simple textbox example, if the ClientIDMode property of the parent naming container (Page in this case) is set to “Predictable” you’ll get this: <input name="ctl00$content$txtName" type="text" id="content_txtName" /> which gives an id that based on walking up to the currently active naming container (the MasterPage content container) and starting the id formatting from there downward. Think of this as a semi unique name that’s guaranteed unique only for the naming container. If, on the other hand, the Page is set to “AutoID” you get the following with Predictable on txtName: <input name="ctl00$content$txtName" type="text" id="ctl00_content_txtName" /> The latter is effectively the same as if you specified AutoID because it inherits the AutoID naming from the Page and Content Master Page control of the page. But again - predictable behavior always depends on the parent naming container and how it generates its id, so the id may not always be exactly the same as the AutoID generated value because somewhere in the NamingContainer chain the ClientIDMode setting may be set to a different value. For example, if you had another naming container in the middle that was set to Static you’d end up effectively with an id that starts with the NamingContainers id rather than the whole ctl000_content munging. The most common use for Predictable is likely to be for data-bound controls, which results in each data bound item getting a unique ClientID. Unfortunately, even here the behavior can be very unpredictable depending on which data-bound control you use - I found significant differences in how template controls in a GridView behave from those that are used in a ListView control. For example, GridView creates clean child ClientIDs, while ListView still has a naming container in the ClientID, presumably because of the template container on which you can’t set ClientIDMode. Predictable is useful, but only if all naming containers down the chain use this setting. Otherwise you’re right back to the munged ids that are pretty unpredictable. Another property, ClientIDRowSuffix, can be used in combination with ClientIDMode of Predictable to force a suffix onto list client controls. For example: <asp:GridView runat="server" ID="gvItems" AutoGenerateColumns="false" ClientIDMode="Static" ClientIDRowSuffix="Id"> <Columns> <asp:TemplateField> <ItemTemplate> <asp:Label runat="server" id="txtName" Text='<%# Eval("Name") %>' ClientIDMode="Predictable"/> </ItemTemplate> </asp:TemplateField> <asp:TemplateField> <ItemTemplate> <asp:Label runat="server" id="txtId" Text='<%# Eval("Id") %>' ClientIDMode="Predictable" /> </ItemTemplate> </asp:TemplateField> </Columns> </asp:GridView> generates client Ids inside of a column in the master page described earlier: <td> <span id="txtName_0">Rick</span> </td> where the value after the underscore is the ClientIDRowSuffix field - in this case “Id” of the item data bound to the control. Note that all of the child controls require ClientIDMode=”Predictable” in order for the ClientIDRowSuffix to be applied, and the parent GridView controls need to be set to Static either explicitly or via Naming Container inheritance to give these simple names. It’s a bummer that ClientIDRowSuffix doesn’t work with Static to produce this automatically. Another real problem is that other controls process the ClientIDMode differently. For example, a ListView control processes the Predictable ClientIDMode differently and produces the following with the Static ListView and Predictable child controls: <span id="ctrl0_txtName_0">Rick</span> I couldn’t even figure out a way using ClientIDMode to get a simple ID that also uses a suffix short of falling back to manually generated ids using <%= %> expressions instead. Given the inconsistencies inside of list controls using <%= %>, ids for the ListView might not be a bad idea anyway. Inherit The final setting is Inherit, which is the default for all controls except Page. This means that controls by default inherit the parent naming container’s ClientIDMode setting. For more detailed information on ClientID behavior and different scenarios you can check out a blog post of mine on this subject: http://www.west-wind.com/weblog/posts/54760.aspx. ClientID Enhancements Summary The ClientIDMode property is a welcome addition to ASP.NET 4.0. To me this is probably the most useful WebForms feature as it allows me to generate clean IDs simply by setting ClientIDMode="Static" on either the page or inside of Web.config (in the Pages section) which applies the setting down to the entire page which is my 95% scenario. For the few cases when it matters - for list controls and inside of multi-use user controls or custom server controls) - I can use Predictable or even AutoID to force controls to unique names. For application-level page development, this is easy to accomplish and provides maximum usability for working with client script code against page controls. ViewStateMode Another area of large criticism for WebForms is ViewState. ViewState is used internally by ASP.NET to persist page-level changes to non-postback properties on controls as pages post back to the server. It’s a useful mechanism that works great for the overall mechanics of WebForms, but it can also cause all sorts of overhead for page operation as ViewState can very quickly get out of control and consume huge amounts of bandwidth in your page content. ViewState can also wreak havoc with client-side scripting applications that modify control properties that are tracked by ViewState, which can produce very unpredictable results on a Postback after client-side updates. Over the years in my own development, I’ve often turned off ViewState on pages to reduce overhead. Yes, you lose some functionality, but you can easily implement most of the common functionality in non-ViewState workarounds. Relying less on heavy ViewState controls and sticking with simpler controls or raw HTML constructs avoids getting around ViewState problems. In ASP.NET 3.x and prior, it wasn’t easy to control ViewState - you could turn it on or off and if you turned it off at the page or web.config level, you couldn’t turn it back on for specific controls. In short, it was an all or nothing approach. With ASP.NET 4.0, the new ViewStateMode property gives you more control. It allows you to disable ViewState globally either on the page or web.config level and then turn it back on for specific controls that might need it. ViewStateMode only works when EnableViewState="true" on the page or web.config level (which is the default). You can then use ViewStateMode of Disabled, Enabled or Inherit to control the ViewState settings on the page. If you’re shooting for minimal ViewState usage, the ideal situation is to set ViewStateMode to disabled on the Page or web.config level and only turn it back on particular controls: <%@Page Language="C#" CodeBehind="WebForm2.aspx.cs" Inherits="Westwind.WebStore.WebForm2" ClientIDMode="Static" ViewStateMode="Disabled" EnableViewState="true" %>  <asp:TextBox runat="server" ID="txtName" ViewStateMode="Enabled" />  <asp:TextBox runat="server" ID="txtAddress" /> Note that the EnableViewState="true" at the Page level isn’t required since it’s the default, but it’s important that the value is true. ViewStateMode has no effect if EnableViewState="false" at the page level. The main benefit of ViewStateMode is that it allows you to more easily turn off ViewState for most of the page and enable only a few key controls that might need it. For me personally, this is a perfect combination as most of my WebForm apps can get away without any ViewState at all. But some controls - especially third party controls - often don’t work well without ViewState enabled, and now it’s much easier to selectively enable controls rather than the old way, which required you to pretty much turn off ViewState for all controls that you didn’t want ViewState on. Inline HTML Encoding HTML encoding is an important feature to prevent cross-site scripting attacks in data entered by users on your site. In order to make it easier to create HTML encoded content, ASP.NET 4.0 introduces a new Expression syntax using <%: %> to encode string values. The encoding expression syntax looks like this: <%: "<script type='text/javascript'>" + "alert('Really?');</script>" %> which produces properly encoded HTML: <script type='text/javascript' >alert('Really?');</script> Effectively this is a shortcut to: <%= HttpUtility.HtmlEncode( "<script type='text/javascript'>" + "alert('Really?');</script>") %> Of course the <%: %> syntax can also evaluate expressions just like <%= %> so the more common scenario applies this expression syntax against data your application is displaying. Here’s an example displaying some data model values: <%: Model.Address.Street %> This snippet shows displaying data from your application’s data store or more importantly, from data entered by users. Anything that makes it easier and less verbose to HtmlEncode text is a welcome addition to avoid potential cross-site scripting attacks. Although I listed Inline HTML Encoding here under WebForms, anything that uses the WebForms rendering engine including ASP.NET MVC, benefits from this feature. ScriptManager Enhancements The ASP.NET ScriptManager control in the past has introduced some nice ways to take programmatic and markup control over script loading, but there were a number of shortcomings in this control. The ASP.NET 4.0 ScriptManager has a number of improvements that make it easier to control script loading and addresses a few of the shortcomings that have often kept me from using the control in favor of manual script loading. The first is the AjaxFrameworkMode property which finally lets you suppress loading the ASP.NET AJAX runtime. Disabled doesn’t load any ASP.NET AJAX libraries, but there’s also an Explicit mode that lets you pick and choose the library pieces individually and reduce the footprint of ASP.NET AJAX script included if you are using the library. There’s also a new EnableCdn property that forces any script that has a new WebResource attribute CdnPath property set to a CDN supplied URL. If the script has this Attribute property set to a non-null/empty value and EnableCdn is enabled on the ScriptManager, that script will be served from the specified CdnPath. [assembly: WebResource( "Westwind.Web.Resources.ww.jquery.js", "application/x-javascript", CdnPath = "http://mysite.com/scripts/ww.jquery.min.js")] Cool, but a little too static for my taste since this value can’t be changed at runtime to point at a debug script as needed, for example. Assembly names for loading scripts from resources can now be simple names rather than fully qualified assembly names, which make it less verbose to reference scripts from assemblies loaded from your bin folder or the assembly reference area in web.config: <asp:ScriptManager runat="server" id="Id" EnableCdn="true" AjaxFrameworkMode="disabled"> <Scripts> <asp:ScriptReference Name="Westwind.Web.Resources.ww.jquery.js" Assembly="Westwind.Web" /> </Scripts> </asp:ScriptManager> The ScriptManager in 4.0 also supports script combining via the CompositeScript tag, which allows you to very easily combine scripts into a single script resource served via ASP.NET. Even nicer: You can specify the URL that the combined script is served with. Check out the following script manager markup that combines several static file scripts and a script resource into a single ASP.NET served resource from a static URL (allscripts.js): <asp:ScriptManager runat="server" id="Id" EnableCdn="true" AjaxFrameworkMode="disabled"> <CompositeScript Path="~/scripts/allscripts.js"> <Scripts> <asp:ScriptReference Path="~/scripts/jquery.js" /> <asp:ScriptReference Path="~/scripts/ww.jquery.js" /> <asp:ScriptReference Name="Westwind.Web.Resources.editors.js" Assembly="Westwind.Web" /> </Scripts> </CompositeScript> </asp:ScriptManager> When you render this into HTML, you’ll see a single script reference in the page: <script src="scripts/allscripts.debug.js" type="text/javascript"></script> All you need to do to make this work is ensure that allscripts.js and allscripts.debug.js exist in the scripts folder of your application - they can be empty but the file has to be there. This is pretty cool, but you want to be real careful that you use unique URLs for each combination of scripts you combine or else browser and server caching will easily screw you up royally. The script manager also allows you to override native ASP.NET AJAX scripts now as any script references defined in the Scripts section of the ScriptManager trump internal references. So if you want custom behavior or you want to fix a possible bug in the core libraries that normally are loaded from resources, you can now do this simply by referencing the script resource name in the Name property and pointing at System.Web for the assembly. Not a common scenario, but when you need it, it can come in real handy. Still, there are a number of shortcomings in this control. For one, the ScriptManager and ClientScript APIs still have no common entry point so control developers are still faced with having to check and support both APIs to load scripts so that controls can work on pages that do or don’t have a ScriptManager on the page. The CdnUrl is static and compiled in, which is very restrictive. And finally, there’s still no control over where scripts get loaded on the page - ScriptManager still injects scripts into the middle of the HTML markup rather than in the header or optionally the footer. This, in turn, means there is little control over script loading order, which can be problematic for control developers. MetaDescription, MetaKeywords Page Properties There are also a number of additional Page properties that correspond to some of the other features discussed in this column: ClientIDMode, ClientTarget and ViewStateMode. Another minor but useful feature is that you can now directly access the MetaDescription and MetaKeywords properties on the Page object to set the corresponding meta tags programmatically. Updating these values programmatically previously required either <%= %> expressions in the page markup or dynamic insertion of literal controls into the page. You can now just set these properties programmatically on the Page object in any Control derived class on the page or the Page itself: Page.MetaKeywords = "ASP.NET,4.0,New Features"; Page.MetaDescription = "This article discusses the new features in ASP.NET 4.0"; Note, that there’s no corresponding ASP.NET tag for the HTML Meta element, so the only way to specify these values in markup and access them is via the @Page tag: <%@Page Language="C#" CodeBehind="WebForm2.aspx.cs" Inherits="Westwind.WebStore.WebForm2" ClientIDMode="Static" MetaDescription="Article that discusses what's new in ASP.NET 4.0" MetaKeywords="ASP.NET,4.0,New Features" %> Nothing earth shattering but quite convenient. Visual Studio 2010 Enhancements for Web Development For Web development there are also a host of editor enhancements in Visual Studio 2010. Some of these are not Web specific but they are useful for Web developers in general. Text Editors Throughout Visual Studio 2010, the text editors have all been updated to a new core engine based on WPF which provides some interesting new features for various code editors including the nice ability to zoom in and out with Ctrl-MouseWheel to quickly change the size of text. There are many more API options to control the editor and although Visual Studio 2010 doesn’t yet use many of these features, we can look forward to enhancements in add-ins and future editor updates from the various language teams that take advantage of the visual richness that WPF provides to editing. On the negative side, I’ve noticed that occasionally the code editor and especially the HTML and JavaScript editors will lose the ability to use various navigation keys like arrows, back and delete keys, which requires closing and reopening the documents at times. This issue seems to be well documented so I suspect this will be addressed soon with a hotfix or within the first service pack. Overall though, the code editors work very well, especially given that they were re-written completely using WPF, which was one of my big worries when I first heard about the complete redesign of the editors. Multi-Targeting Visual Studio now targets all versions of the .NET framework from 2.0 forward. You can use Visual Studio 2010 to work on your ASP.NET 2, 3.0 and 3.5 applications which is a nice way to get your feet wet with the new development environment without having to make changes to existing applications. It’s nice to have one tool to work in for all the different versions. Multi-Monitor Support One cool feature of Visual Studio 2010 is the ability to drag windows out of the Visual Studio environment and out onto the desktop including onto another monitor easily. Since Web development often involves working with a host of designers at the same time - visual designer, HTML markup window, code behind and JavaScript editor - it’s really nice to be able to have a little more screen real estate to work on each of these editors. Microsoft made a welcome change in the environment. IntelliSense Snippets for HTML and JavaScript Editors The HTML and JavaScript editors now finally support IntelliSense scripts to create macro-based template expansions that have been in the core C# and Visual Basic code editors since Visual Studio 2005. Snippets allow you to create short XML-based template definitions that can act as static macros or real templates that can have replaceable values that can be embedded into the expanded text. The XML syntax for these snippets is straight forward and it’s pretty easy to create custom snippets manually. You can easily create snippets using XML and store them in your custom snippets folder (C:\Users\rstrahl\Documents\Visual Studio 2010\Code Snippets\Visual Web Developer\My HTML Snippets and My JScript Snippets), but it helps to use one of the third-party tools that exist to simplify the process for you. I use SnippetEditor, by Bill McCarthy, which makes short work of creating snippets interactively (http://snippeteditor.codeplex.com/). Note: You may have to manually add the Visual Studio 2010 User specific Snippet folders to this tool to see existing ones you’ve created. Code snippets are some of the biggest time savers and HTML editing more than anything deals with lots of repetitive tasks that lend themselves to text expansion. Visual Studio 2010 includes a slew of built-in snippets (that you can also customize!) and you can create your own very easily. If you haven’t done so already, I encourage you to spend a little time examining your coding patterns and find the repetitive code that you write and convert it into snippets. I’ve been using CodeRush for this for years, but now you can do much of the basic expansion natively for HTML and JavaScript snippets. jQuery Integration Is Now Native jQuery is a popular JavaScript library and recently Microsoft has recently stated that it will become the primary client-side scripting technology to drive higher level script functionality in various ASP.NET Web projects that Microsoft provides. In Visual Studio 2010, the default full project template includes jQuery as part of a new project including the support files that provide IntelliSense (-vsdoc files). IntelliSense support for jQuery is now also baked into Visual Studio 2010, so unlike Visual Studio 2008 which required a separate download, no further installs are required for a rich IntelliSense experience with jQuery. Summary ASP.NET 4.0 brings many useful improvements to the platform, but thankfully most of the changes are incremental changes that don’t compromise backwards compatibility and they allow developers to ease into the new features one feature at a time. None of the changes in ASP.NET 4.0 or Visual Studio 2010 are monumental or game changers. The bigger features are language and .NET Framework changes that are also optional. This ASP.NET and tools release feels more like fine tuning and getting some long-standing kinks worked out of the platform. It shows that the ASP.NET team is dedicated to paying attention to community feedback and responding with changes to the platform and development environment based on this feedback. If you haven’t gotten your feet wet with ASP.NET 4.0 and Visual Studio 2010, there’s no reason not to give it a shot now - the ASP.NET 4.0 platform is solid and Visual Studio 2010 works very well for a brand new release. Check it out. © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET

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LWJGL SlickUtil Texture Binding

- by Matthew Dockerty

I am making a 3D game using LWJGL and I have a texture class with static variables so that I only need to load textures once, even if I need to use them more than once. I am using Slick Util for this. When I bind a texture it works fine, but then when I try to render something else after I have rendered the model with the texture, the texture is still being bound. How do I unbind the texture and set the rendermode to the one that was in use before any textures were bound? Some of my code is below. The problem I am having is the player texture is being used in the box drawn around the player after it the model has been rendered. Model.java public class Model { public List<Vector3f> vertices = new ArrayList<Vector3f>(); public List<Vector3f> normals = new ArrayList<Vector3f>(); public ArrayList<Vector2f> textureCoords = new ArrayList<Vector2f>(); public List<Face> faces = new ArrayList<Face>(); public static Model TREE; public static Model PLAYER; public static void loadModels() { try { TREE = OBJLoader.loadModel(new File("assets/model/tree_pine_0.obj")); PLAYER = OBJLoader.loadModel(new File("assets/model/player.obj")); } catch (Exception e) { e.printStackTrace(); } } public void render(Vector3f position, Vector3f scale, Vector3f rotation, Texture texture, float shinyness) { glPushMatrix(); { texture.bind(); glColor3f(1, 1, 1); glTranslatef(position.x, position.y, position.z); glScalef(scale.x, scale.y, scale.z); glRotatef(rotation.x, 1, 0, 0); glRotatef(rotation.y, 0, 1, 0); glRotatef(rotation.z, 0, 0, 1); glMaterialf(GL_FRONT, GL_SHININESS, shinyness); glBegin(GL_TRIANGLES); { for (Face face : faces) { Vector2f t1 = textureCoords.get((int) face.textureCoords.x - 1); glTexCoord2f(t1.x, t1.y); Vector3f n1 = normals.get((int) face.normal.x - 1); glNormal3f(n1.x, n1.y, n1.z); Vector3f v1 = vertices.get((int) face.vertex.x - 1); glVertex3f(v1.x, v1.y, v1.z); Vector2f t2 = textureCoords.get((int) face.textureCoords.y - 1); glTexCoord2f(t2.x, t2.y); Vector3f n2 = normals.get((int) face.normal.y - 1); glNormal3f(n2.x, n2.y, n2.z); Vector3f v2 = vertices.get((int) face.vertex.y - 1); glVertex3f(v2.x, v2.y, v2.z); Vector2f t3 = textureCoords.get((int) face.textureCoords.z - 1); glTexCoord2f(t3.x, t3.y); Vector3f n3 = normals.get((int) face.normal.z - 1); glNormal3f(n3.x, n3.y, n3.z); Vector3f v3 = vertices.get((int) face.vertex.z - 1); glVertex3f(v3.x, v3.y, v3.z); } texture.release(); } glEnd(); } glPopMatrix(); } } Textures.java public class Textures { public static Texture FLOOR; public static Texture PLAYER; public static Texture SKYBOX_TOP; public static Texture SKYBOX_BOTTOM; public static Texture SKYBOX_FRONT; public static Texture SKYBOX_BACK; public static Texture SKYBOX_LEFT; public static Texture SKYBOX_RIGHT; public static void loadTextures() { try { FLOOR = TextureLoader.getTexture("PNG", new FileInputStream(new File("assets/model/floor.png"))); FLOOR.setTextureFilter(GL11.GL_NEAREST); PLAYER = TextureLoader.getTexture("PNG", new FileInputStream(new File("assets/model/tree_pine_0.png"))); PLAYER.setTextureFilter(GL11.GL_NEAREST); SKYBOX_TOP = TextureLoader.getTexture("PNG", new FileInputStream(new File("assets/textures/skybox_top.png"))); SKYBOX_TOP.setTextureFilter(GL11.GL_NEAREST); SKYBOX_BOTTOM = TextureLoader.getTexture("PNG", new FileInputStream(new File("assets/textures/skybox_bottom.png"))); SKYBOX_BOTTOM.setTextureFilter(GL11.GL_NEAREST); SKYBOX_FRONT = TextureLoader.getTexture("PNG", new FileInputStream(new File("assets/textures/skybox_front.png"))); SKYBOX_FRONT.setTextureFilter(GL11.GL_NEAREST); SKYBOX_BACK = TextureLoader.getTexture("PNG", new FileInputStream(new File("assets/textures/skybox_back.png"))); SKYBOX_BACK.setTextureFilter(GL11.GL_NEAREST); SKYBOX_LEFT = TextureLoader.getTexture("PNG", new FileInputStream(new File("assets/textures/skybox_left.png"))); SKYBOX_LEFT.setTextureFilter(GL11.GL_NEAREST); SKYBOX_RIGHT = TextureLoader.getTexture("PNG", new FileInputStream(new File("assets/textures/skybox_right.png"))); SKYBOX_RIGHT.setTextureFilter(GL11.GL_NEAREST); } catch (Exception e) { e.printStackTrace(); } } } Player.java public class Player { private Vector3f position; private float yaw; private float moveSpeed; public Player(float x, float y, float z, float yaw, float moveSpeed) { this.position = new Vector3f(x, y, z); this.yaw = yaw; this.moveSpeed = moveSpeed; } public void update() { if (Keyboard.isKeyDown(Keyboard.KEY_W)) walkForward(moveSpeed); if (Keyboard.isKeyDown(Keyboard.KEY_S)) walkBackwards(moveSpeed); if (Keyboard.isKeyDown(Keyboard.KEY_A)) strafeLeft(moveSpeed); if (Keyboard.isKeyDown(Keyboard.KEY_D)) strafeRight(moveSpeed); if (Mouse.isButtonDown(0)) yaw += Mouse.getDX(); LowPolyRPG.getInstance().getCamera().setPosition(-position.x, -position.y, -position.z); LowPolyRPG.getInstance().getCamera().setYaw(yaw); } public void walkForward(float distance) { position.setX(position.getX() + distance * (float) Math.sin(Math.toRadians(yaw))); position.setZ(position.getZ() - distance * (float) Math.cos(Math.toRadians(yaw))); } public void walkBackwards(float distance) { position.setX(position.getX() - distance * (float) Math.sin(Math.toRadians(yaw))); position.setZ(position.getZ() + distance * (float) Math.cos(Math.toRadians(yaw))); } public void strafeLeft(float distance) { position.setX(position.getX() + distance * (float) Math.sin(Math.toRadians(yaw - 90))); position.setZ(position.getZ() - distance * (float) Math.cos(Math.toRadians(yaw - 90))); } public void strafeRight(float distance) { position.setX(position.getX() + distance * (float) Math.sin(Math.toRadians(yaw + 90))); position.setZ(position.getZ() - distance * (float) Math.cos(Math.toRadians(yaw + 90))); } public void render() { Model.PLAYER.render(new Vector3f(position.x, position.y + 12, position.z), new Vector3f(3, 3, 3), new Vector3f(0, -yaw + 90, 0), Textures.PLAYER, 128); GL11.glPushMatrix(); GL11.glTranslatef(position.getX(), position.getY(), position.getZ()); GL11.glRotatef(-yaw, 0, 1, 0); GL11.glScalef(5.8f, 21, 2.2f); GL11.glDisable(GL11.GL_LIGHTING); GL11.glLineWidth(3); GL11.glBegin(GL11.GL_LINE_STRIP); GL11.glColor3f(1, 1, 1); glVertex3f(1f, 0f, -1f); glVertex3f(-1f, 0f, -1f); glVertex3f(-1f, 1f, -1f); glVertex3f(1f, 1f, -1f); glVertex3f(-1f, 0f, 1f); glVertex3f(1f, 0f, 1f); glVertex3f(1f, 1f, 1f); glVertex3f(-1f, 1f, 1f); glVertex3f(1f, 1f, -1f); glVertex3f(-1f, 1f, -1f); glVertex3f(-1f, 1f, 1f); glVertex3f(1f, 1f, 1f); glVertex3f(1f, 0f, 1f); glVertex3f(-1f, 0f, 1f); glVertex3f(-1f, 0f, -1f); glVertex3f(1f, 0f, -1f); glVertex3f(1f, 0f, 1f); glVertex3f(1f, 0f, -1f); glVertex3f(1f, 1f, -1f); glVertex3f(1f, 1f, 1f); glVertex3f(-1f, 0f, -1f); glVertex3f(-1f, 0f, 1f); glVertex3f(-1f, 1f, 1f); glVertex3f(-1f, 1f, -1f); GL11.glEnd(); GL11.glEnable(GL11.GL_LIGHTING); GL11.glPopMatrix(); } public Vector3f getPosition() { return new Vector3f(-position.x, -position.y, -position.z); } public float getX() { return position.getX(); } public float getY() { return position.getY(); } public float getZ() { return position.getZ(); } public void setPosition(Vector3f position) { this.position = position; } public void setPosition(float x, float y, float z) { this.position.setX(x); this.position.setY(y); this.position.setZ(z); } } Thanks for the help.

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Apache mod_rewrite driving me mad

- by WishCow

The scenario I have a webhost that is shared among multiple sites, the directory layout looks like this: siteA/ - css/ - js/ - index.php siteB/ - css/ - js/ - index.php siteC/ . . . The DocumentRoot is at the top level, so, to access siteA, you type http://webhost/siteA in your browser, to access siteB, you type http://webhost/siteB, and so on. Now I have to deploy my own site, which was designed with having 3 VirtualHosts in mind, so my structure looks like this: siteD/ - sites/sitename.com/ - log/ - htdocs/ - index.php - sites/static.sitename.com - log/ - htdocs/ - css - js - sites/admin.sitename.com - log/ - htdocs/ - index.php As you see, the problem is that my index.php files are not at the top level directory, unlike the already existing sites on the webhost. Each VirtualHost should point to the corresponding htdocs/ folder: http://siteD.com -> siteD/sites/sitename.com/htdocs http://static.siteD.com -> siteD/sites/static.sitename.com/htdocs http://admin.siteD.com -> siteD/sites/admin.sitename.com/htdocs The problem I cannot have VirtualHosts on this host, so I have to emulate it somehow, possibly with mod_rewrite. The idea Have some predefined parts in all of the links on the site, that I can identify, and route accordingly to the correct file, with mod_rewrite. Examples: http://webhost/siteD/static/js/something.js -> siteD/sites/static.sitename.com/htdocs/js/something.js http://webhost/siteD/static/css/something.css -> siteD/sites/static.sitename.com/htdocs/css/something.css http://webhost/siteD/admin/something -> siteD/sites/admin.sitename.com/htdocs/index.php http://webhost/siteD/admin/sub/something -> siteD/sites/admin.sitename.com/htdocs/index.php http://webhost/siteD/something -> siteD/sites/sitename.com/htdocs/index.php http://webhost/siteD/sub/something -> siteD/sites/sitename.com/htdocs/index.php Anything that starts with http://url/sitename/admin/(.*) will get rewritten, to point to siteD/sites/admin.sitename.com/htdocs/index.php Anything that starts with http://url/sitename/static/(.*) will get rewritten, to point to siteD/sites/static.sitename.com/htdocs/$1 Anything that starts with http://url/sitename/(.*) AND did not have a match already from above, will get rewritten to point to siteD/sites/sitename.com/htdocs/index.php The solution Here is the .htaccess file that I've come up with: RewriteEngine On RewriteBase / RewriteCond %{REQUEST_URI} ^/siteD/static/(.*)$ [NC] RewriteRule ^siteD/static/(.*)$ siteD/sites/static/htdocs/$1 [L] RewriteCond %{REQUEST_URI} ^/siteD/admin/(.*)$ [NC] RewriteRule ^siteD/(.*)$ siteD/sites/admin/htdocs/index.php [L,QSA] So far, so good. It's all working. Now to add the last rule: RewriteCond %{REQUEST_URI} ^/siteD/(.*)$ [NC] RewriteRule ^siteD/(.*)$ siteD/sites/public/htdocs/index.php [L,QSA] And it's broken. The last rule catches everything, even the ones that have static/ or admin/ in them. Why? Shouldn't the [L] flag stop the rewriting process in the first two cases? Why is the third case evaluated? Is there a better way of solving this? I'm not sticking to rewritemod, anything is fine as long as it does not need access to server-level config. I don't have access to RewriteLog, or anything like that. Please help :(

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.NET 4.0 Dynamic object used statically?

- by Kevin Won

I've gotten quite sick of XML configuration files in .NET and want to replace them with a format that is more sane. Therefore, I'm writing a config file parser for C# applications that will take a custom config file format, parse it, and create a Python source string that I can then execute in C# and use as a static object (yes that's right--I want a static (not the static type dyanamic) object in the end). Here's an example of what my config file looks like: // my custom config file format GlobalName: ExampleApp Properties { ExternalServiceTimeout: "120" } Python { // this allows for straight python code to be added to handle custom config def MyCustomPython: return "cool" } Using ANTLR I've created a Lexer/Parser that will convert this format to a Python script. So assume I have that all right and can take the .config above and run my Lexer/Parser on it to get a Python script out the back (this has the added benefit of giving me a validation tool for my config). By running the resultant script in C# // simplified example of getting the dynamic python object in C# // (not how I really do it) ScriptRuntime py = Python.CreateRuntime(); dynamic conf = py.UseFile("conftest.py"); dynamic t = conf.GetConfTest("test"); I can get a dynamic object that has my configuration settings. I can now get my config file settings in C# by invoking a dynamic method on that object: //C# calling a method on the dynamic python object var timeout = t.GetProperty("ExternalServiceTimeout"); //the config also allows for straight Python scripting (via the Python block) var special = t.MyCustonPython(); of course, I have no type safety here and no intellisense support. I have a dynamic representation of my config file, but I want a static one. I know what my Python object's type is--it is actually newing up in instance of a C# class. But since it's happening in python, it's type is not the C# type, but dynamic instead. What I want to do is then cast the object back to the C# type that I know the object is: // doesn't work--can't cast a dynamic to a static type (nulls out) IConfigSettings staticTypeConfig = t as IConfigSettings Is there any way to figure out how to cast the object to the static type? I'm rather doubtful that there is... so doubtful that I took another approach of which I'm not entirely sure about. I'm wondering if someone has a better way... So here's my current tactic: since I know the type of the python object, I am creating a C# wrapper class: public class ConfigSettings : IConfigSettings that takes in a dynamic object in the ctor: public ConfigSettings(dynamic settings) { this.DynamicProxy = settings; } public dynamic DynamicProxy { get; private set; } Now I have a reference to the Python dynamic object of which I know the type. So I can then just put wrappers around the Python methods that I know are there: // wrapper access to the underlying dynamic object // this makes my dynamic object appear 'static' public string GetSetting(string key) { return this.DynamicProxy.GetProperty(key).ToString(); } Now the dynamic object is accessed through this static proxy and thus can obviously be passed around in the static C# world via interface, etc: // dependency inject the dynamic object around IBusinessLogic logic = new BusinessLogic(IConfigSettings config); This solution has the benefits of all the static typing stuff we know and love while at the same time giving me the option of 'bailing out' to dynamic too: // the DynamicProxy property give direct access to the dynamic object var result = config.DynamicProxy.MyCustomPython(); but, man, this seems rather convoluted way of getting to an object that is a static type in the first place! Since the whole dynamic/static interaction world is new to me, I'm really questioning if my solution is optimal or if I'm missing something (i.e. some way of casting that dynamic object to a known static type) about how to bridge the chasm between these two universes.

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Why a graphics overflow problem as a result of a for loop?

- by sonny5

using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; using System.Drawing.Imaging; using System.Drawing.Drawing2D; public class Form1 : System.Windows.Forms.Form { public static float WXmin; public static float WYmin; public static float WXmax; public static float WYmax; public static int VXmin; public static int VYmin; public static int VXmax; public static int VYmax; public static float Wx; public static float Wy; public static float Vx; public static float Vy; public Form1() { InitializeComponent(); } private void InitializeComponent() { this.ClientSize = new System.Drawing.Size(400, 300); this.Text="Pass Args"; this.Paint += new System.Windows.Forms.PaintEventHandler(this.doLine); //this.Paint += new System.PaintEventHandler(this.eachCornerPix); //eachCornerPix(out Wx, out Wy, out Vx, out Vy); } static void Main() { Application.Run(new Form1()); } private void doLine(object sender, System.Windows.Forms.PaintEventArgs e) { Graphics g = e.Graphics; g.FillRectangle(Brushes.White, this.ClientRectangle); Pen p = new Pen(Color.Black); g.DrawLine(p, 0, 0, 100, 100); // draw DOWN in y, which is positive since no matrix called eachCornerPix(sender, e, out Wx, out Wy, out Vx, out Vy); p.Dispose(); } private void eachCornerPix (object sender, System.EventArgs e, out float Wx, out float Wy, out float Vx, out float Vy) { Wx = 0.0f; Wy = 0.0f; Vx = 0.0f; Vy = 0.0f; Graphics g = this.CreateGraphics(); Pen penBlu = new Pen(Color.Blue, 2); SolidBrush redBrush = new SolidBrush(Color.Red); int width = 2; // 1 pixel wide in x int height = 2; float [] Wxc = {0.100f, 5.900f, 5.900f, 0.100f}; float [] Wyc = {0.100f, 0.100f, 3.900f, 3.900f}; Console.WriteLine("Wxc[0] = {0}", Wxc[0]); Console.WriteLine("Wyc[3] = {0}", Wyc[3]); /* for (int i = 0; i<3; i++) { Wx = Wxc[i]; Wy = Wyc[i]; Vx = ((Wx - WXmin)*((VXmax-VXmin)+VXmin)/(WXmax-WXmin)); Vy = ((Wy - WYmin)*(VYmax-VYmin)/(WYmax-WYmin)+VYmin); Console.WriteLine("eachCornerPix Vx= {0}", Vx); Console.WriteLine("eachCornerPix Vy= {0}", Vy); g.FillRectangle(redBrush, Vx, Vy, width, height); } */ // What is there about this for loop that will not run? // When the comments above and after the for loop are removed, it gets an overflow? g.Dispose(); } }

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Choosing a type for search results in C#

- by Chris M

I have a result set that will never exceed 500; the results that come back from the web-service are assigned to a search results object. The data from the webservice is about 2mb; the bit I want to use is about a third of each record, so this allows me to cache and quickly manipulate it. I want to be able to sort and filter the results with the least amount of overhead and as fast as possible so I used the VCSKICKS timing class to measure their performance Average Total (10,000) Type Create Sort Create Sort HashSet 0.1579 0.0003 1579 3 IList 0.0633 0.0002 633 2 IQueryable 0.0072 0.0432 72 432 Measured in Seconds using http://www.vcskicks.com/algorithm-performance.php I created the hashset through a for loop over the web-service response (adding to the hashset). The List & IQueryable were created using LINQ. Question I can understand why HashSet takes longer to create (the foreach loop vs linq); but why would IQueryable take longer to sort than the other two; and finally is there a better way to assign the HashSet. Thanks Actual Program public class Program { private static AuthenticationHeader _authHeader; private static OPSoapClient _opSession; private static AccommodationSearchResponse _searchResults; private static HashSet<SearchResults> _myHash; private static IList<SearchResults> _myList; private static IQueryable<SearchResults> _myIQuery; static void Main(string[] args) { #region Setup WebService _authHeader = new AuthenticationHeader { UserName = "xx", Password = "xx" }; _opSession = new OPSoapClient(); #region Setup Search Results _searchResults = _opgSession.SearchCR(_authHeader, "ENG", "GBP", "GBR"); #endregion Setup Search Results #endregion Setup WebService // HASHSET SpeedTester hashTest = new SpeedTester(TestHashSet); hashTest.RunTest(); Console.WriteLine("- Hash Test \nAverage Running Time: {0}; Total Time: {1}", hashTest.AverageRunningTime, hashTest.TotalRunningTime); SpeedTester hashSortTest = new SpeedTester(TestSortingHashSet); hashSortTest.RunTest(); Console.WriteLine("- Hash Sort Test \nAverage Running Time: {0}; Total Time: {1}", hashSortTest.AverageRunningTime, hashSortTest.TotalRunningTime); // ILIST SpeedTester listTest = new SpeedTester(TestList); listTest.RunTest(); Console.WriteLine("- List Test \nAverage Running Time: {0}; Total Time: {1}", listTest.AverageRunningTime, listTest.TotalRunningTime); SpeedTester listSortTest = new SpeedTester(TestSortingList); listSortTest.RunTest(); Console.WriteLine("- List Sort Test \nAverage Running Time: {0}; Total Time: {1}", listSortTest.AverageRunningTime, listSortTest.TotalRunningTime); // IQUERIABLE SpeedTester iqueryTest = new SpeedTester(TestIQueriable); iqueryTest.RunTest(); Console.WriteLine("- iquery Test \nAverage Running Time: {0}; Total Time: {1}", iqueryTest.AverageRunningTime, iqueryTest.TotalRunningTime); SpeedTester iquerySortTest = new SpeedTester(TestSortableIQueriable); iquerySortTest.RunTest(); Console.WriteLine("- iquery Sort Test \nAverage Running Time: {0}; Total Time: {1}", iquerySortTest.AverageRunningTime, iquerySortTest.TotalRunningTime); } static void TestHashSet() { var test = _searchResults.Items; _myHash = new HashSet<SearchResults>(); foreach(var x in test) { _myHash.Add(new SearchResults { Ref = x.Ref, Price = x.StandardPrice }); } } static void TestSortingHashSet() { var sorted = _myHash.OrderBy(s => s.Price); } static void TestList() { var test = _searchResults.Items; _myList = (from x in test select new SearchResults { Ref = x.Ref, Price = x.StandardPrice }).ToList(); } static void TestSortingList() { var sorted = _myList.OrderBy(s => s.Price); } static void TestIQueriable() { var test = _searchResults.Items; _myIQuery = (from x in test select new SearchResults { Ref = x.Ref, Price = x.StandardPrice }).AsQueryable(); } static void TestSortableIQueriable() { var sorted = _myIQuery.OrderBy(s => s.Price); } }

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Table Name is null in the sqlite database in android device

- by Mahe

I am building a simple app which stores some contacts and retrieves contacts in android phone device. I have created my own database and a table and inserting the values to the table in phone. My phone is not rooted. So I cannot access the files, but I see that values are stored in the table. And tested on a emulator also. Till here it is fine. Display all the contacts in a list by fetching data from table. This is also fine. But the problem is When I am trying to delete the record, it shows the table name is null in the logcat(not an exception), and the data is not deleted. But in emulator the data is getting deleted from table. I am not able to achieve this through phone. This is my code for deleting, public boolean onContextItemSelected(MenuItem item) { super.onContextItemSelected(item); AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo) item .getMenuInfo(); int menuItemIndex = item.getItemId(); String[] menuItems = getResources().getStringArray(R.array.menu); String menuItemName = menuItems[menuItemIndex]; String listItemName = Customers[info.position]; if (item.getTitle().toString().equalsIgnoreCase("Delete")) { Toast.makeText( context, "Selected List item is: " + listItemName + "MenuItem is: " + menuItemName, Toast.LENGTH_LONG).show(); DB = context.openOrCreateDatabase("CustomerDetails.db", MODE_PRIVATE, null); try { int pos = info.position; pos = pos + 1; Log.d("", "customers[pos]: " + Customers[info.position]); Cursor c = DB .rawQuery( "Select customer_id,first_name,last_name from CustomerInfo", null); int rowCount = c.getCount(); DB.delete(Table_name, "customer_id" + "=" + String.valueOf(pos), null); DB.close(); Log.d("", "" + String.valueOf(pos)); Toast.makeText(context, "Deleted Customer", Toast.LENGTH_LONG) .show(); // Customers[info.position]=null; getCustomers(); } catch (Exception e) { Toast.makeText(context, "Delete unsuccessfull", Toast.LENGTH_LONG).show(); } } this is my logcat, 07-02 10:12:42.976: D/Cursor(1560): Database path: CustomerDetails.db 07-02 10:12:42.976: D/Cursor(1560): Table name : null 07-02 10:12:42.984: D/Cursor(1560): Database path: CustomerDetails.db 07-02 10:12:42.984: D/Cursor(1560): Table name : null Don't know the reason why data is not being deleted. Data exists in the table. This is the specification I have given for creating the table public static String customer_id="customer_id"; public static String site_id="site_id"; public static String last_name="last_name"; public static String first_name="first_name"; public static String phone_number="phone_number"; public static String address="address"; public static String city="city"; public static String state="state"; public static String zip="zip"; public static String email_address="email_address"; public static String custlat="custlat"; public static String custlng="custlng"; public static String Table_name="CustomerInfo"; final SQLiteDatabase DB = context.openOrCreateDatabase( "CustomerDetails.db", MODE_PRIVATE, null); final String CREATE_TABLE = "create table if not exists " + Table_name + " (" + customer_id + " integer primary key autoincrement, " + first_name + " text not null, " + last_name + " text not null, " + phone_number+ " integer not null, " + address+ " text not null, " + city+ " text not null, " + state+ " text not null, " + zip+ " integer not null, " + email_address+ " text not null, " + custlat+ " double, " + custlng+ " double " +" );"; DB.execSQL(CREATE_TABLE); DB.close(); Please correct my code. I am struggling from two days. Any help is appreciated!!

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Add elements to Arraylist and it replaces all previous elements in Java

- by pie154

I am adding elements to a ArrayList and it adds the first one correctly but then when I add any subsequent elements it wipes replaces the other elements with the value form the most recently added and adds a new element to the ArrayList. I ran test using arraylist and ints and even another created class and it worked perfectly but soemthing about the custon class i am using here causes problems. The code for the array list is public static void main(String args[]){ List<BasicEvent> list = new ArrayList<BasicEvent>(); list.add(new BasicEvent("Basic", "Door", 9, 4444, new Date(12,04,2010), new Time(12,04,21), 1, 0.98, 0)); list.add(new BasicEvent("Composite", "Door", 125, 4444, new Date(12,04,2010), new Time(12,04,20), 1, 0.98, 1)); list.add(new BasicEvent("Basic", "Door", 105, 88, new Date(12,04,2010), new Time(12,05,23), 1, 0.98, 0)); list.add(new BasicEvent("Basic", "Door", 125, 12, new Date(12,04,2010), new Time(12,05,28), 1, 0.98, 1)); list.add(new BasicEvent("Basic", "Door", 129, 25, new Date(12,04,2010), new Time(12,05,30), 1, 0.98, 0)); list.add(new BasicEvent("Basic", "Door", 125, 63, new Date(12,04,2010), new Time(12,04,20), 1, 0.98, 1)); list.add(new BasicEvent("Basic", "Detect", 127, 9, new Date(12,04,2010), new Time(12,05,29), 1, 0.98, -1)); for(int i=0;i<list.size();i++) {System.out.println("list a poition " + i + " is " + BasicEvent.basicToString(list.get(i)));} And the code for the custom class basicEvent is public class BasicEvent { public static String Level; public static String EType; public static double xPos; public static double yPos; public static Date date; public static Time time; public static double Rlb; public static double Sig; public static int Reserved; public BasicEvent(String L, String E, double X, double Y, Date D, Time T, double R, double S, int Res){ Level = L; EType = E; xPos = X; yPos = Y; date = D; time = T; Rlb = R; Sig = S; Reserved = Res; }; public static String basicToString(BasicEvent bse){ String out = bse.getLevel() + ";" + bse.getEtype() + ";" + bse.getxPos() + ";" + bse.getyPos() + ";" + bse.getDate().dateAsString() + ";" + bse.getTime().timeAsString() + ";" + bse.getRlb() + ";" + bse.getSig() + ";" + bse.getReserved(); return out; }

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SWIG & Java Use of carrays.i and array_functions for C Array of Strings

- by c12

I have the below configuration where I'm trying to create a test C function that returns a pointer to an Array of Strings and then wrap that using SWIG's carrays.i and array_functions so that I can access the Array elements in Java. Uncertainties: %array_functions(char, SWIGArrayUtility); - not sure if char is correct inline char *getCharArray() - not sure if C function signature is correct String result = getCharArray(); - String return seems odd, but that's what is generated by SWIG SWIG.i: %module Test %{ #include "test.h" %} %include <carrays.i> %array_functions(char, SWIGArrayUtility); %include "test.h" %pragma(java) modulecode=%{ public static char[] getCharArrayImpl() { final int num = numFoo(); char ret[] = new char[num]; String result = getCharArray(); for (int i = 0; i < num; ++i) { ret[i] = SWIGArrayUtility_getitem(result, i); } return ret; } %} Inline Header C Function: #ifndef TEST_H #define TEST_H inline static unsigned short numFoo() { return 3; } inline char *getCharArray(){ static char* foo[3]; foo[0]="ABC"; foo[1]="5CDE"; foo[2]="EEE6"; return foo; } #endif Java Main Tester: public class TestMain { public static void main(String[] args) { System.loadLibrary("TestJni"); char[] test = Test.getCharArrayImpl(); System.out.println("length=" + test.length); for(int i=0; i < test.length; i++){ System.out.println(test[i]); } } } Java Main Tester Output: length=3 ? ? , SWIG Generated Java APIs: public class Test { public static String new_SWIGArrayUtility(int nelements) { return TestJNI.new_SWIGArrayUtility(nelements); } public static void delete_SWIGArrayUtility(String ary) { TestJNI.delete_SWIGArrayUtility(ary); } public static char SWIGArrayUtility_getitem(String ary, int index) { return TestJNI.SWIGArrayUtility_getitem(ary, index); } public static void SWIGArrayUtility_setitem(String ary, int index, char value) { TestJNI.SWIGArrayUtility_setitem(ary, index, value); } public static int numFoo() { return TestJNI.numFoo(); } public static String getCharArray() { return TestJNI.getCharArray(); } public static char[] getCharArrayImpl() { final int num = numFoo(); char ret[] = new char[num]; String result = getCharArray(); System.out.println("result=" + result); for (int i = 0; i < num; ++i) { ret[i] = SWIGArrayUtility_getitem(result, i); System.out.println("ret[" + i + "]=" + ret[i]); } return ret; } }

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How can I make this client as a multithread client?

- by Johanna

Hi, I have read a lot about multithread client but for this one,I can not make it multithread! would you please help me? public class MainClient implements Runnable{ private static InformationClass info = new InformationClass(); private static Socket c; private static String text; public static String getText() { return text; } public static void setText(String text) { MainClient.text = text; } private static PrintWriter os; private static BufferedReader is; static boolean closed = false; /** * @param args the command line arguments */ public static void main(String[] args) { MainFrame farme = new MainFrame(); farme.setVisible(true); try { c = new Socket("localhost", 5050); os = new PrintWriter(c.getOutputStream(), true); is = new BufferedReader(new InputStreamReader(c.getInputStream())); } catch (UnknownHostException ex) { Logger.getLogger(MainClient.class.getName()).log(Level.SEVERE, null, ex); } catch (IOException ex) { Logger.getLogger(MainClient.class.getName()).log(Level.SEVERE, null, ex); } } public static void active() { String teXt = MainClient.getText(); System.out.println(teXt); os.println(teXt); try { String line = is.readLine(); System.out.println("Text received: " + line); os.flush(); is.close(); is.close(); c.close(); } catch (IOException ex) { Logger.getLogger(MainClient.class.getName()).log(Level.SEVERE, null, ex); } } } also active method will be called when the client write something on the text area and then clicks on the send button. 2) also i have a question that: in the other class I have this action performed for my send button,does it mean that client is multithread?? private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) { new Thread(new Runnable() { @Override public void run() { // This gets run in a background thread String text = jTextArea1.getText(); jTextArea2.append(client.getCurrentName() + " : " + text + "\n"); MainClient.setText(client.getCurrentName() + " : " + text + "\n"); clear(); MainClient.active(); } }).start(); } Last EDIT: this is my active method: public static void active() { String teXt = MainClient.getText(); os.println(teXt); String line = is.readLine(); System.out.println("Text received: " + line); os.flush(); is.close(); is.close(); c.close(); }

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Banshee encountered a Fatal Error (sqlite error 11: database disk image is malformed)

- by Nik

I am running ubuntu 10.10 Maverick Meerkat, and recently I am helping in testing out indicator-weather using the unstable buids. However there was a bug which caused my system to freeze suddenly (due to indicator-weather not ubuntu) and the only way to recover is to do a hard reset of the system. This happened a couple of times. And when i tried to open banshee after a couple of such resets I get the following fatal error which forces me to quit banshee. The screenshot is not clear enough to read the error, so I am posting it below, An unhandled exception was thrown: Sqlite error 11: database disk image is malformed (SQL: BEGIN TRANSACTION; DELETE FROM CoreSmartPlaylistEntries WHERE SmartPlaylistID IN (SELECT SmartPlaylistID FROM CoreSmartPlaylists WHERE IsTemporary = 1); DELETE FROM CoreSmartPlaylists WHERE IsTemporary = 1; COMMIT TRANSACTION) at Hyena.Data.Sqlite.Connection.CheckError (Int32 errorCode, System.String sql) [0x00000] in <filename unknown>:0 at Hyena.Data.Sqlite.Connection.Execute (System.String sql) [0x00000] in <filename unknown>:0 at Hyena.Data.Sqlite.HyenaSqliteCommand.Execute (Hyena.Data.Sqlite.HyenaSqliteConnection hconnection, Hyena.Data.Sqlite.Connection connection) [0x00000] in <filename unknown>:0 Exception has been thrown by the target of an invocation. at System.Reflection.MonoCMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in <filename unknown>:0 at System.Reflection.MonoCMethod.Invoke (BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in <filename unknown>:0 at System.Reflection.ConstructorInfo.Invoke (System.Object[] parameters) [0x00000] in <filename unknown>:0 at System.Activator.CreateInstance (System.Type type, Boolean nonPublic) [0x00000] in <filename unknown>:0 at System.Activator.CreateInstance (System.Type type) [0x00000] in <filename unknown>:0 at Banshee.Gui.GtkBaseClient.Startup () [0x00000] in <filename unknown>:0 at Hyena.Gui.CleanRoomStartup.Startup (Hyena.Gui.StartupInvocationHandler startup) [0x00000] in <filename unknown>:0 .NET Version: 2.0.50727.1433 OS Version: Unix 2.6.35.27 Assembly Version Information: gkeyfile-sharp (1.0.0.0) Banshee.AudioCd (1.9.0.0) Banshee.MiniMode (1.9.0.0) Banshee.CoverArt (1.9.0.0) indicate-sharp (0.4.1.0) notify-sharp (0.4.0.0) Banshee.SoundMenu (1.9.0.0) Banshee.Mpris (1.9.0.0) Migo (1.9.0.0) Banshee.Podcasting (1.9.0.0) Banshee.Dap (1.9.0.0) Banshee.LibraryWatcher (1.9.0.0) Banshee.MultimediaKeys (1.9.0.0) Banshee.Bpm (1.9.0.0) Banshee.YouTube (1.9.0.0) Banshee.WebBrowser (1.9.0.0) Banshee.Wikipedia (1.9.0.0) pango-sharp (2.12.0.0) Banshee.Fixup (1.9.0.0) Banshee.Widgets (1.9.0.0) gio-sharp (2.14.0.0) gudev-sharp (1.0.0.0) Banshee.Gio (1.9.0.0) Banshee.GStreamer (1.9.0.0) System.Configuration (2.0.0.0) NDesk.DBus.GLib (1.0.0.0) gconf-sharp (2.24.0.0) Banshee.Gnome (1.9.0.0) Banshee.NowPlaying (1.9.0.0) Mono.Cairo (2.0.0.0) System.Xml (2.0.0.0) Banshee.Core (1.9.0.0) Hyena.Data.Sqlite (1.9.0.0) System.Core (3.5.0.0) gdk-sharp (2.12.0.0) Mono.Addins (0.4.0.0) atk-sharp (2.12.0.0) Hyena.Gui (1.9.0.0) gtk-sharp (2.12.0.0) Banshee.ThickClient (1.9.0.0) Nereid (1.9.0.0) NDesk.DBus.Proxies (0.0.0.0) Mono.Posix (2.0.0.0) NDesk.DBus (1.0.0.0) glib-sharp (2.12.0.0) Hyena (1.9.0.0) System (2.0.0.0) Banshee.Services (1.9.0.0) Banshee (1.9.0.0) mscorlib (2.0.0.0) Platform Information: Linux 2.6.35-27-generic i686 unknown GNU/Linux Disribution Information: [/etc/lsb-release] DISTRIB_ID=Ubuntu DISTRIB_RELEASE=10.10 DISTRIB_CODENAME=maverick DISTRIB_DESCRIPTION="Ubuntu 10.10" [/etc/debian_version] squeeze/sid Just to make it clear, this happened only after the hard resets and not before. I used to use banshee everyday and it worked perfectly. Can anyone help me fix this?

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Understanding C# async / await (1) Compilation

- by Dixin

Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is called MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been cleaned up so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# level syntax sugar. There is no difference to await a async method or a normal method. A method returning Task will be awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } The above code is already cleaned up, but there are still a lot of things. More clean up can be done, and the state machine can be very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> void IAsyncStateMachine.MoveNext() { try { switch (this.State) { // Orginal code is splitted by "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; IAsyncStateMachine this1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this1.MoveNext()); // Callback break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; IAsyncStateMachine this2 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this2.MoveNext()); // Callback break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync_(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; (multiCallMethodAsyncStateMachine as IAsyncStateMachine).MoveNext(); // Original code are in this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clear - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback Since it is about callback, the simplification can go even further – the entire state machine can be completely purged. Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is literally pretending to wait. In a await expression, a Task object will be return immediately so that caller is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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Understanding C# async / await (1) Compilation

- by Dixin

Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is named MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine, MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been refactored, so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# language level syntax sugar. There is no difference to await a async method or a normal method. As long as a method returns Task, it is awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } Once again, the above state machine code is already refactored, but it still has a lot of things. More clean up can be done if we only keep the core logic, and the state machine can become very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> public void MoveNext() // IAsyncStateMachine member. { try { switch (this.State) { // Original code is split by "await"s into "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; MultiCallMethodAsyncStateMachine that1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => that1.MoveNext()); break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; MultiCallMethodAsyncStateMachine that2 = this; this.currentTaskToAwait.ContinueWith(_ => that2.MoveNext()); break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] public void SetStateMachine(IAsyncStateMachine stateMachine) // IAsyncStateMachine member. { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; multiCallMethodAsyncStateMachine.MoveNext(); // Original code are moved into this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clean - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback If we focus on the point of callback, the simplification can go even further – the entire state machine can be completely purged, and we can just keep the code inside MoveNext(). Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is not to wait. In a await expression, a Task object will be return immediately so that execution is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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controller path not found for static images? asp.net mvc routing issue?

- by rksprst

I have an image folder stored at ~/Content/Images/ I am loading these images via <img src="/Content/Images/Image.png" /> Recently, the images aren't loading and I am getting the following errors in my error log. What's weird is that some images load fine, while others do not load. Anyone have any idea what is wrong with my routes? Am I missing an ignore route for the /Content/ folder? I am also getting the same error for favicon.ico and a bunch of other image files... <Fatal> -- 3/25/2010 2:32:38 AM -- System.Web.HttpException: The controller for path '/Content/Images/box_bottom.png' could not be found or it does not implement IController. at System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(Type controllerType) at System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) at System.Web.Mvc.MvcHandler.ProcessRequest(HttpContextBase httpContext) at System.Web.Mvc.MvcHandler.ProcessRequest(HttpContext httpContext) at System.Web.Mvc.MvcHandler.System.Web.IHttpHandler.ProcessRequest(HttpContext httpContext) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) My current routes look like this: routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "Default", // Route name "{controller}/{action}/{id}", // URL with parameters new { controller = "Home", action = "Index", id = "" } // Parameter defaults ); routes.MapRoute( "ControllerDefault", // Route name "{controller}/project/{projectid}/{action}/{searchid}", // URL with parameters new { controller = "Listen", action = "Index", searchid = "" } // Parameter defaults ); Thanks!

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What makes static initialization functions good, bad, or otherwise?

- by Richard Levasseur

Suppose you had code like this: _READERS = None _WRITERS = None def Init(num_readers, reader_params, num_writers, writer_params, ...args...): ...logic... _READERS = new ReaderPool(num_readers, reader_params) _WRITERS = new WriterPool(num_writers, writer_params) ...more logic... class Doer: def __init__(...args...): ... def Read(self, ...args...): c = _READERS.get() try: ...work with conn finally: _READERS.put(c) def Writer(...): ...similar to Read()... To me, this is a bad pattern to follow, some cons: Doers can be created without its preconditions being satisfied The code isn't easily testable because ConnPool can't be directly mocked out. Init has to be called right the first time. If its changed so it can be called multiple times, extra logic has to be added to check if variables are already defined, and lots of NULL values have to be passed around to skip re-initializing. In the event of threads, the above becomes more complicated by adding locking Globals aren't being used to communicate state (which isn't strictly bad, but a code smell) On the other hand, some pros: its very convenient to call Init(5, "user/pass", 2, "user/pass") It simple and "clean" Personally, I think the cons outweigh the pros, that is, testability and assured preconditions outweigh simplicity and convenience.

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