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• Using 2D sprites and 3D models together

  - by Sweta Dwivedi

  I have gone through a few posts that talks about changing the GraphicsDevice.BlendState and GraphicsDevice.DepthStencilState (SpriteBatch & Render states). . however even after changing the states .. i cant see my 3D model on the screen.. I see the model for a second before i draw my video in the background. . Here is the code: case GameState.InGame: GraphicsDevice.Clear(Color.AliceBlue); spriteBatch.Begin(); if (player.State != MediaState.Stopped) { videoTexture = player.GetTexture(); } Rectangle screen = new Rectangle(GraphicsDevice.Viewport.X, GraphicsDevice.Viewport.Y, GraphicsDevice.Viewport.Width, GraphicsDevice.Viewport.Height); // Draw the video, if we have a texture to draw. if (videoTexture != null) { spriteBatch.Draw(videoTexture, screen, Color.White); if (Selected_underwater == true) { spriteBatch.DrawString(font, "MaxX , MaxY" + maxWidth + "," + maxHeight, new Vector2(400, 10), Color.Red); spriteBatch.Draw(kinectRGBVideo, new Rectangle(0, 0, 100, 100), Color.White); spriteBatch.Draw(butterfly, handPosition, Color.White); foreach (AnimatedSprite a in aSprites) { a.Draw(spriteBatch); } } if(Selected_planet == true) { spriteBatch.Draw(kinectRGBVideo, new Rectangle(0, 0, 100, 100), Color.White); spriteBatch.Draw(butterfly, handPosition, Color.White); spriteBatch.Draw(videoTexture,screen,Color.White); GraphicsDevice.BlendState = BlendState.Opaque; GraphicsDevice.DepthStencilState = DepthStencilState.Default; GraphicsDevice.SamplerStates[0] = SamplerState.LinearWrap; foreach (_3DModel m in Solar) { m.DrawModel(); } } spriteBatch.End(); break;

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• Talent Management in Aerospace & Defense this Thursday, April 8th

  - by jay.richey

  While many industries struggle to recover from one of the most devastating recessions in history, the aerospace and defense industry plans for record growth. And key to that growth is better management of the workforce. A&D companies are currently faced with a multitude of workforce challenges including an aging and retiring workforce, knowledge gaps created as the workforce leaves, a surge in use of contingent workers, and antiquated work environments and practices that make it difficult to attract the next generation of workers. If you are in the DC area, register to attend the Oracle Aerospace and Defense Contractors Summit in Reston this Thursday, April 8th from 8am-5pm and hear Jay Richey, Oracle HCM Applications Product Marketing Director, discuss trends in the A&D talent space and smart strategies on retaining that talent. You will also hear Accenture discuss their recent survey results - Keys to Managing Human Capital within the A&D Enterprise. Register today at http://www.oracle.com/dm/10q3field/43453_ev_oracle_aerospace_apr10.html

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• GAME MAKER Problem with sprites! Can't see the sprite after mouse action

  - by user46882

  I have got a problem in Game Maker Pro: http://www.directupload.net/file/d/3646/egdpdu6u_gif.htm At the start we see a white square moving. If I press a key the square stop to move and the background changes to white. If the background changes to white a new animation/sprite should play on the same position where the white square was. BUT IT DOESNT! (Actually it is still there! It just does not move and this is fine) The animation is basically a sprite animation with some outlines of the square. If I press a key again, the background changes to white and we see the animation of the sprite.. but we do not see the animation of the sprites when it does not move. And this is strange!! I want to have the animation of the square when it doesn't move. But I don't get it.. by the way.. the .gif is a old version. I allready fixed the problem with the moving animation.. but I am still not able to play the animation if the square does not fly. The color of the animation is allready set to green or something! for better contrast. But still.. can't see it. Here is the code: obj.weisse.kugel.stepevent = the white square with the movements and sprite animations etc. if (global.kweiss == 1 ) { // vspeed = 8; //visible = true // sprite_index=spr_weisse_kugel; image_speed = 0; image_index = 0; } else if (global.kweiss == 0) { sprite_index=spr_animation_fade_out; image_speed =0.2; image_index=image_number-1 vspeed = 0; //visible = false // } then I have 1 create event for all the global.variables obj.global_var globalvar kweiss; kweiss = 1; globalvar kschwarz; kschwarz = 0; and then I have 1 controll stepevent in a new obj: if device_mouse_check_button_pressed (0, mb_left) { if background_color = c_black { background_color = c_white } else { background_color = c_black } // change of the square to white if (global.kweiss = 0) { global.kweiss = 1; } else { global.kweiss = 0; } if (global.kschwarz = 0) // change the square to black (other bullets.. we do not need this at the moment!) { global.kschwarz = 1; } else { global.kschwarz = 0; } Many thanks in advance

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• Rsync problem...filenames

  - by Jay White

  I'm trying to back up users Chrome Sessions with Rsync with the following command: rsync -e "ssh -i new.key" -r --verbose -tz --stats --progress --delete \ '/cygdrive/c/Users/jay/AppData/Local/Google/Chrome/User Data/Default/Current Session' \ user@host:"/chrome sessions/" Except this doesn't work exactly, as I get a file called chrome in a sessions directory that is already present on the server. Why is this?

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• Is there any hueristic to polygonize a closed 2d-raster shape with n triangles?

  - by Arthur Wulf White

  Lets say we have a 2d image black on white that shows a closed geometric shape. Is there any (not naive brute force) algorithm that approximates that shape as closely as possible with n triangles? If you want a formal definition for as closely as possible: Approximate the shape with a polygon that when rendered into a new 2d image will match the largest number of pixels possible with the original image.

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• Are there white lists for Yahoo, Gmail, Hotmail and AOL?

  - by Waleed Eissa

  In my website (under development), the members can send messages to each other which are sent directly to their email, now I'm worried that some members can send spam to other members (I have a spam filter but it doesn't give 100% protection as you know), I'm worried that my domain might get blacklisted on Yahoo, Gmail, Hotmail or AOL which will cause any messages sent from my domain to end up in the spam folder, this is why I want to add the domain of my website to their whitelists (if they exist). P.S. I don't want to use private messages that members check on the site and I have my reason for this. Thanks

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• Google maps not showing satellite background - streets on white background.

  - by WooYek

  Custom map is broken on satellite view, does not show satellite imagery. Any ideas, what's wrong? Overlays are also broken - they're not transparent. Code: <div id="map_canvas" class="grid_8 omega" style="width:460px; height: 420px"></div> <script src="http://maps.google.com/maps?file=api&amp;v=3&amp;sensor=true&amp;key=my-key-is-here" type="text/javascript"></script> <script type="text/javascript"> function initialize() { if (GBrowserIsCompatible()) { var map = new GMap2(document.getElementById("map_canvas")); map.setCenter(new GLatLng(52.229676, 21.012229), 13); map.setMapType(G_HYBRID_MAP); map.setUIToDefault(); } var geocoder = new GClientGeocoder(); function showAddress(address) { geocoder.getLatLng(address, function(point) { if (!point) { alert('Nie mozna znalezc adresu: '+address); } else { map.setCenter(point, 13); var marker = new GMarker(point); map.addOverlay(marker); marker.openInfoWindowHtml(address); } } ); } showAddress('some address goes here') } $('body').ready(initialize); $('body').unload(GUnload); </script>

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• css/html: white space break fix and now cant code fine?

  - by Karem

  Yes, so I got the problem that if you type a long sentence with no space e.g eeeeeeeeeeeeeeeeeeeeeeee, it will break itself, but then now I would need to start typing some ugly non-breaking coding. Example: http://jsfiddle.net/r3CFJ/ I need to have everything in one sentence in order not to make it break itself. Check here to see the result of not having everything in one sentence: http://jsfiddle.net/r3CFJ/1/ How can I fix this please any solutions?? as my further coding will get very ugly and not readable?

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• What size paper or white board do you use for brainstorming / planning ?

  - by Naveen

  Use a small notepad, and turning pages interferes with flow of thought. Use a whiteboard and marker, and you write bigger when you are standing up, so you don't necessarily get more ideas on the board... A friend of mine has his entire wall in his office, lab made up of whiteboard material... This is a more specific question on a related topic.

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• How to get rid of white space between css horizontal list items?

  - by Curyous

  I've got the following test page and css. When displayed, there is a 4px gap between each list item. How do I get the items to be next to each other? <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Frameset//EN" "http://www.w3.org/TR/html4/frameset.dtd"> <html> <head> <link type="text/css" rel="stylesheet" href="/stylesheets/test.css" /> </head> <body> <div> <ul class="nav"> <li class="nav"><a class="nav" href="#">One1</a></li> <li class="nav"><a class="nav" href="#">Two</a></li> <li class="nav"><a class="nav" href="#">Three</a></li> <li class="nav"><a class="nav" href="#">Four</a></li> </ul> </div> </body> </html> The css: ul.nav, ul li.nav { display: inline; margin: 0px; padding: 0px; } ul.nav { list-style-type: none; } li.nav { background-color: red; } a.nav { background-color: green; padding: 10px; margin: 0px; } a:hover.nav { background-color: gray; }

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• White-box testing in Javascript - how to deal with privacy?

  - by Max Shawabkeh

  I'm writing unit tests for a module in a small Javascript application. In order to keep the interface clean, some of the implementation details are closed over by an anonymous function (the usual JS pattern for privacy). However, while testing I need to access/mock/verify the private parts. Most of the tests I've written previously have been in Python, where there are no real private variables (members, identifiers, whatever you want to call them). One simply suggests privacy via a leading underscore for the users, and freely ignores it while testing the code. In statically typed OO languages I suppose one could make private members accessible to tests by converting them to be protected and subclassing the object to be tested. In Javascript, the latter doesn't apply, while the former seems like bad practice. I could always wall back to black box testing and simply check the final results. It's the simplest and cleanest approach, but unfortunately not really detailed enough for my needs. So, is there a standard way of keeping variables private while still retaining some backdoors for testing in Javascript?

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• XNA 4.0 SpriteBatch.Draw Out Of Memory Exception Thrown

  - by RustyGearGames

  Well, first of all, my guess is that I'm calling the spritebatch.draw() method to many times, but I need to (Or, it's the only way I can figure out how to) Draw my in-game windows. I'll just go ahead and dump my code; using System; using System.Text; 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; namespace System.Window { class Window { #region Variables public Texture2D importedTexture; public Texture2D WindowSkin; public RenderTarget2D currentWindow; public RenderTarget2D windowTexture; public Vector2 pos; public int prevWindowWidth; public int prevWindowHeight; public int windowWidth; public int windowHeight; public bool visible; public bool active; public bool drawNew; #region Rectangles public Rectangle clickRect; public Rectangle topLeftRect; public Rectangle topRightRect; public Rectangle buttonRect; public Rectangle botLeftRect; public Rectangle botRightRect; #endregion #endregion public Window() { } public void Initialize(GraphicsDevice g, Texture2D ws, Texture2D it, int w, int h, bool v, bool a) { WindowSkin = ws; importedTexture = it; windowWidth = w; prevWindowWidth = w; windowHeight = h; prevWindowHeight = h; windowTexture = new RenderTarget2D(g, windowWidth, windowHeight); currentWindow = windowTexture; visible = v; active = a; drawNew = true; topLeftRect = new Rectangle(0, 0, 32, 32); topRightRect = new Rectangle(32, 0, 32, 32); buttonRect = new Rectangle(64, 0, 32, 32); botLeftRect = new Rectangle(0, 64, 32, 32); botRightRect = new Rectangle(64, 64, 32, 32); } public void Update(GraphicsDevice g, Vector2 p, int width, int height) { prevWindowWidth = windowWidth; prevWindowHeight = windowHeight; pos = p; windowWidth = width; windowHeight = height; windowTexture = new RenderTarget2D(g, windowWidth+2, windowHeight+2); } public void Draw(SpriteBatch s, GraphicsDevice g) { s.Draw(currentWindow, pos, new Rectangle(0, 0, windowWidth, windowHeight), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); } public void DrawNewWindow(SpriteBatch s, GraphicsDevice g) { g.SetRenderTarget(windowTexture); g.Clear(Color.Transparent); s.Begin(); #region Draw Background for (int w = 3; w < (windowWidth); w += 32) { for (int h = 32; h < (windowHeight); h += 32) { s.Draw(WindowSkin, new Vector2(w, h), new Rectangle(32, 32, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); } } #endregion s.Draw(importedTexture, new Vector2(3, 32), new Rectangle(0, 0, importedTexture.Width, importedTexture.Height), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); #region Draw resizables for (int i = 32; i < (windowWidth - 64); i += 32) { s.Draw(WindowSkin, new Vector2(i, 0), new Rectangle(16, 0, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); } for (int i = 32; i < (windowWidth - 32); i += 32) { s.Draw(WindowSkin, new Vector2(i, windowHeight - 32), new Rectangle(32, 64, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); } for (int i = 64; i < (windowHeight - 32); i += 32) { s.Draw(WindowSkin, new Vector2(0, i), new Rectangle(0, 48, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); } for (int i = 64; i < (windowHeight - 32); i += 32) { s.Draw(WindowSkin, new Vector2(windowWidth - 32, i), new Rectangle(64, 48, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); } #endregion #region Draw Corners s.Draw(WindowSkin, new Vector2(0, 0), topLeftRect, Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); s.Draw(WindowSkin, new Vector2(0, 32), new Rectangle(0, 32, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); s.Draw(WindowSkin, new Vector2(windowWidth - 64, 0), topRightRect, Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); s.Draw(WindowSkin, new Vector2(windowWidth - 32, 32), new Rectangle(64, 32, 32, 32), Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); s.Draw(WindowSkin, new Vector2(windowWidth - 32, 0), buttonRect, Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); s.Draw(WindowSkin, new Vector2(0, windowHeight - 32), botLeftRect, Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); s.Draw(WindowSkin, new Vector2(windowWidth - 32, windowHeight - 32), botRightRect, Color.White, 0, Vector2.Zero, 1.0f, SpriteEffects.None, 0); #endregion s.End(); currentWindow = windowTexture; } } } It's all nice and configured for my little windowskin texture, and such. the only problem is that it will get a little laggy, and then completely crash on me about a minute into running it. It throws an Out Of Memory Exception, but I don't know and can't find any other topic or post on this relating to spritebatch. Does anybody have any suggestions on how I can get this working and not take up much memory? I would think this as an easy, cost effective way of drawing a window. I'm just not sure how cut down on my draw calls, or get any of that memory back.

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• ASP.NET Web API Exception Handling

  - by Fredrik N

  When I talk about exceptions in my product team I often talk about two kind of exceptions, business and critical exceptions. Business exceptions are exceptions thrown based on “business rules”, for example if you aren’t allowed to do a purchase. Business exceptions in most case aren’t important to log into a log file, they can directly be shown to the user. An example of a business exception could be "DeniedToPurchaseException”, or some validation exceptions such as “FirstNameIsMissingException” etc. Critical Exceptions are all other kind of exceptions such as the SQL server is down etc. Those kind of exception message need to be logged and should not reach the user, because they can contain information that can be harmful if it reach out to wrong kind of users. I often distinguish business exceptions from critical exceptions by creating a base class called BusinessException, then in my error handling code I catch on the type BusinessException and all other exceptions will be handled as critical exceptions. This blog post will be about different ways to handle exceptions and how Business and Critical Exceptions could be handled. Web API and Exceptions the basics When an exception is thrown in a ApiController a response message will be returned with a status code set to 500 and a response formatted by the formatters based on the “Accept” or “Content-Type” HTTP header, for example JSON or XML. Here is an example:   public IEnumerable<string> Get() { throw new ApplicationException("Error!!!!!"); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The response message will be: HTTP/1.1 500 Internal Server Error Content-Length: 860 Content-Type: application/json; charset=utf-8 { "ExceptionType":"System.ApplicationException","Message":"Error!!!!!","StackTrace":" at ..."} .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The stack trace will be returned to the client, this is because of making it easier to debug. Be careful so you don’t leak out some sensitive information to the client. So as long as you are developing your API, this is not harmful. In a production environment it can be better to log exceptions and return a user friendly exception instead of the original exception. There is a specific exception shipped with ASP.NET Web API that will not use the formatters based on the “Accept” or “Content-Type” HTTP header, it is the exception is the HttpResponseException class. Here is an example where the HttpReponseExcetpion is used: // GET api/values [ExceptionHandling] public IEnumerable<string> Get() { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError)); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The response will not contain any content, only header information and the status code based on the HttpStatusCode passed as an argument to the HttpResponseMessage. Because the HttpResponsException takes a HttpResponseMessage as an argument, we can give the response a content: public IEnumerable<string> Get() { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("My Error Message"), ReasonPhrase = "Critical Exception" }); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The code above will have the following response:   HTTP/1.1 500 Critical Exception Content-Length: 5 Content-Type: text/plain; charset=utf-8 My Error Message .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The Content property of the HttpResponseMessage doesn’t need to be just plain text, it can also be other formats, for example JSON, XML etc. By using the HttpResponseException we can for example catch an exception and throw a user friendly exception instead: public IEnumerable<string> Get() { try { DoSomething(); return new string[] { "value1", "value2" }; } catch (Exception e) { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("An error occurred, please try again or contact the administrator."), ReasonPhrase = "Critical Exception" }); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Adding a try catch to every ApiController methods will only end in duplication of code, by using a custom ExceptionFilterAttribute or our own custom ApiController base class we can reduce code duplicationof code and also have a more general exception handler for our ApiControllers . By creating a custom ApiController’s and override the ExecuteAsync method, we can add a try catch around the base.ExecuteAsync method, but I prefer to skip the creation of a own custom ApiController, better to use a solution that require few files to be modified. The ExceptionFilterAttribute has a OnException method that we can override and add our exception handling. Here is an example: using System; using System.Diagnostics; using System.Net; using System.Net.Http; using System.Web.Http; using System.Web.Http.Filters; public class ExceptionHandlingAttribute : ExceptionFilterAttribute { public override void OnException(HttpActionExecutedContext context) { if (context.Exception is BusinessException) { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(context.Exception.Message), ReasonPhrase = "Exception" }); } //Log Critical errors Debug.WriteLine(context.Exception); throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("An error occurred, please try again or contact the administrator."), ReasonPhrase = "Critical Exception" }); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: Something to have in mind is that the ExceptionFilterAttribute will be ignored if the ApiController action method throws a HttpResponseException. The code above will always make sure a HttpResponseExceptions will be returned, it will also make sure the critical exceptions will show a more user friendly message. The OnException method can also be used to log exceptions. By using a ExceptionFilterAttribute the Get() method in the previous example can now look like this: public IEnumerable<string> Get() { DoSomething(); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To use the an ExceptionFilterAttribute, we can for example add the ExceptionFilterAttribute to our ApiControllers methods or to the ApiController class definition, or register it globally for all ApiControllers. You can read more about is here. Note: If something goes wrong in the ExceptionFilterAttribute and an exception is thrown that is not of type HttpResponseException, a formatted exception will be thrown with stack trace etc to the client. How about using a custom IHttpActionInvoker? We can create our own IHTTPActionInvoker and add Exception handling to the invoker. The IHttpActionInvoker will be used to invoke the ApiController’s ExecuteAsync method. Here is an example where the default IHttpActionInvoker, ApiControllerActionInvoker, is used to add exception handling: public class MyApiControllerActionInvoker : ApiControllerActionInvoker { public override Task<HttpResponseMessage> InvokeActionAsync(HttpActionContext actionContext, System.Threading.CancellationToken cancellationToken) { var result = base.InvokeActionAsync(actionContext, cancellationToken); if (result.Exception != null && result.Exception.GetBaseException() != null) { var baseException = result.Exception.GetBaseException(); if (baseException is BusinessException) { return Task.Run<HttpResponseMessage>(() => new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(baseException.Message), ReasonPhrase = "Error" }); } else { //Log critical error Debug.WriteLine(baseException); return Task.Run<HttpResponseMessage>(() => new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(baseException.Message), ReasonPhrase = "Critical Error" }); } } return result; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } You can register the IHttpActionInvoker with your own IoC to resolve the MyApiContollerActionInvoker, or add it in the Global.asax: GlobalConfiguration.Configuration.Services.Remove(typeof(IHttpActionInvoker), GlobalConfiguration.Configuration.Services.GetActionInvoker()); GlobalConfiguration.Configuration.Services.Add(typeof(IHttpActionInvoker), new MyApiControllerActionInvoker()); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   How about using a Message Handler for Exception Handling? By creating a custom Message Handler, we can handle error after the ApiController and the ExceptionFilterAttribute is invoked and in that way create a global exception handler, BUT, the only thing we can take a look at is the HttpResponseMessage, we can’t add a try catch around the Message Handler’s SendAsync method. The last Message Handler that will be used in the Wep API pipe-line is the HttpControllerDispatcher and this Message Handler is added to the HttpServer in an early stage. The HttpControllerDispatcher will use the IHttpActionInvoker to invoke the ApiController method. The HttpControllerDipatcher has a try catch that will turn ALL exceptions into a HttpResponseMessage, so that is the reason why a try catch around the SendAsync in a custom Message Handler want help us. If we create our own Host for the Wep API we could create our own custom HttpControllerDispatcher and add or exception handler to that class, but that would be little tricky but is possible. We can in a Message Handler take a look at the HttpResponseMessage’s IsSuccessStatusCode property to see if the request has failed and if we throw the HttpResponseException in our ApiControllers, we could use the HttpResponseException and give it a Reason Phrase and use that to identify business exceptions or critical exceptions. I wouldn’t add an exception handler into a Message Handler, instead I should use the ExceptionFilterAttribute and register it globally for all ApiControllers. BUT, now to another interesting issue. What will happen if we have a Message Handler that throws an exception?  Those exceptions will not be catch and handled by the ExceptionFilterAttribute. I found a  bug in my previews blog post about “Log message Request and Response in ASP.NET WebAPI” in the MessageHandler I use to log incoming and outgoing messages. Here is the code from my blog before I fixed the bug:   public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var corrId = string.Format("{0}{1}", DateTime.Now.Ticks, Thread.CurrentThread.ManagedThreadId); var requestInfo = string.Format("{0} {1}", request.Method, request.RequestUri); var requestMessage = await request.Content.ReadAsByteArrayAsync(); await IncommingMessageAsync(corrId, requestInfo, requestMessage); var response = await base.SendAsync(request, cancellationToken); var responseMessage = await response.Content.ReadAsByteArrayAsync(); await OutgoingMessageAsync(corrId, requestInfo, responseMessage); return response; } protected abstract Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message); protected abstract Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   If a ApiController throws a HttpResponseException, the Content property of the HttpResponseMessage from the SendAsync will be NULL. So a null reference exception is thrown within the MessageHandler. The yellow screen of death will be returned to the client, and the content is HTML and the Http status code is 500. The bug in the MessageHandler was solved by adding a check against the HttpResponseMessage’s IsSuccessStatusCode property: public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var corrId = string.Format("{0}{1}", DateTime.Now.Ticks, Thread.CurrentThread.ManagedThreadId); var requestInfo = string.Format("{0} {1}", request.Method, request.RequestUri); var requestMessage = await request.Content.ReadAsByteArrayAsync(); await IncommingMessageAsync(corrId, requestInfo, requestMessage); var response = await base.SendAsync(request, cancellationToken); byte[] responseMessage; if (response.IsSuccessStatusCode) responseMessage = await response.Content.ReadAsByteArrayAsync(); else responseMessage = Encoding.UTF8.GetBytes(response.ReasonPhrase); await OutgoingMessageAsync(corrId, requestInfo, responseMessage); return response; } protected abstract Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message); protected abstract Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } If we don’t handle the exceptions that can occur in a custom Message Handler, we can have a hard time to find the problem causing the exception. The savior in this case is the Global.asax’s Application_Error: protected void Application_Error() { var exception = Server.GetLastError(); Debug.WriteLine(exception); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } I would recommend you to add the Application_Error to the Global.asax and log all exceptions to make sure all kind of exception is handled. Summary There are different ways we could add Exception Handling to the Wep API, we can use a custom ApiController, ExceptionFilterAttribute, IHttpActionInvoker or Message Handler. The ExceptionFilterAttribute would be a good place to add a global exception handling, require very few modification, just register it globally for all ApiControllers, even the IHttpActionInvoker can be used to minimize the modifications of files. Adding the Application_Error to the global.asax is a good way to catch all unhandled exception that can occur, for example exception thrown in a Message Handler.   If you want to know when I have posted a blog post, you can follow me on twitter @fredrikn

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• Use Extension method to write cleaner code

  - by Fredrik N

  This blog post will show you step by step to refactoring some code to be more readable (at least what I think). Patrik Löwnedahl gave me some of the ideas when we where talking about making code much cleaner. The following is an simple application that will have a list of movies (Normal and Transfer). The task of the application is to calculate the total sum of each movie and also display the price of each movie. class Program { enum MovieType { Normal, Transfer } static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfNormalMovie = 0; int totalPriceOfTransferMovie = 0; foreach (var movie in movies) { if (movie == MovieType.Normal) { totalPriceOfNormalMovie += 2; Console.WriteLine("$2"); } else if (movie == MovieType.Transfer) { totalPriceOfTransferMovie += 3; Console.WriteLine("$3"); } } } private static IEnumerable<MovieType> GetMovies() { return new List<MovieType>() { MovieType.Normal, MovieType.Transfer, MovieType.Normal }; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } In the code above I’m using an enum, a good way to add types (isn’t it ;)). I also use one foreach loop to calculate the price, the loop has a condition statement to check what kind of movie is added to the list of movies. I want to reuse the foreach only to increase performance and let it do two things (isn’t that smart of me?! ;)). First of all I can admit, I’m not a big fan of enum. Enum often results in ugly condition statements and can be hard to maintain (if a new type is added we need to check all the code in our app to see if we use the enum somewhere else). I don’t often care about pre-optimizations when it comes to write code (of course I have performance in mind). I rather prefer to use two foreach to let them do one things instead of two. So based on what I don’t like and Martin Fowler’s Refactoring catalog, I’m going to refactoring this code to what I will call a more elegant and cleaner code. First of all I’m going to use Split Loop to make sure the foreach will do one thing not two, it will results in two foreach (Don’t care about performance here, if the results will results in bad performance, you can refactoring later, but computers are so fast to day, so iterating through a list is not often so time consuming.) Note: The foreach actually do four things, will come to is later. var movies = GetMovies(); int totalPriceOfNormalMovie = 0; int totalPriceOfTransferMovie = 0; foreach (var movie in movies) { if (movie == MovieType.Normal) { totalPriceOfNormalMovie += 2; Console.WriteLine("$2"); } } foreach (var movie in movies) { if (movie == MovieType.Transfer) { totalPriceOfTransferMovie += 3; Console.WriteLine("$3"); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To remove the condition statement we can use the Where extension method added to the IEnumerable<T> and is located in the System.Linq namespace: foreach (var movie in movies.Where( m => m == MovieType.Normal)) { totalPriceOfNormalMovie += 2; Console.WriteLine("$2"); } foreach (var movie in movies.Where( m => m == MovieType.Transfer)) { totalPriceOfTransferMovie += 3; Console.WriteLine("$3"); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The above code will still do two things, calculate the total price, and display the price of the movie. I will not take care of it at the moment, instead I will focus on the enum and try to remove them. One way to remove enum is by using the Replace Conditional with Polymorphism. So I will create two classes, one base class called Movie, and one called MovieTransfer. The Movie class will have a property called Price, the Movie will now hold the price:   public class Movie { public virtual int Price { get { return 2; } } } public class MovieTransfer : Movie { public override int Price { get { return 3; } } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The following code has no enum and will use the new Movie classes instead: class Program { static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfNormalMovie = 0; int totalPriceOfTransferMovie = 0; foreach (var movie in movies.Where( m => m is Movie)) { totalPriceOfNormalMovie += movie.Price; Console.WriteLine(movie.Price); } foreach (var movie in movies.Where( m => m is MovieTransfer)) { totalPriceOfTransferMovie += movie.Price; Console.WriteLine(movie.Price); } } private static IEnumerable<Movie> GetMovies() { return new List<Movie>() { new Movie(), new MovieTransfer(), new Movie() }; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   If you take a look at the foreach now, you can see it still actually do two things, calculate the price and display the price. We can do some more refactoring here by using the Sum extension method to calculate the total price of the movies:   static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfNormalMovie = movies.Where(m => m is Movie) .Sum(m => m.Price); int totalPriceOfTransferMovie = movies.Where(m => m is MovieTransfer) .Sum(m => m.Price); foreach (var movie in movies.Where( m => m is Movie)) Console.WriteLine(movie.Price); foreach (var movie in movies.Where( m => m is MovieTransfer)) Console.WriteLine(movie.Price); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now when the Movie object will hold the price, there is no need to use two separate foreach to display the price of the movies in the list, so we can use only one instead: foreach (var movie in movies) Console.WriteLine(movie.Price); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } If we want to increase the Maintainability index we can use the Extract Method to move the Sum of the prices into two separate methods. The name of the method will explain what we are doing: static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfMovie = TotalPriceOfMovie(movies); int totalPriceOfTransferMovie = TotalPriceOfMovieTransfer(movies); foreach (var movie in movies) Console.WriteLine(movie.Price); } private static int TotalPriceOfMovieTransfer(IEnumerable<Movie> movies) { return movies.Where(m => m is MovieTransfer) .Sum(m => m.Price); } private static int TotalPriceOfMovie(IEnumerable<Movie> movies) { return movies.Where(m => m is Movie) .Sum(m => m.Price); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now to the last thing, I love the ForEach method of the List<T>, but the IEnumerable<T> doesn’t have it, so I created my own ForEach extension, here is the code of the ForEach extension method: public static class LoopExtensions { public static void ForEach<T>(this IEnumerable<T> values, Action<T> action) { Contract.Requires(values != null); Contract.Requires(action != null); foreach (var v in values) action(v); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } I will now replace the foreach by using this ForEach method: static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfMovie = TotalPriceOfMovie(movies); int totalPriceOfTransferMovie = TotalPriceOfMovieTransfer(movies); movies.ForEach(m => Console.WriteLine(m.Price)); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The ForEach on the movies will now display the price of the movie, but maybe we want to display the name of the movie etc, so we can use Extract Method by moving the lamdba expression into a method instead, and let the method explains what we are displaying: movies.ForEach(DisplayMovieInfo); private static void DisplayMovieInfo(Movie movie) { Console.WriteLine(movie.Price); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now the refactoring is done! Here is the complete code:   class Program { static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfMovie = TotalPriceOfMovie(movies); int totalPriceOfTransferMovie = TotalPriceOfMovieTransfer(movies); movies.ForEach(DisplayMovieInfo); } private static void DisplayMovieInfo(Movie movie) { Console.WriteLine(movie.Price); } private static int TotalPriceOfMovieTransfer(IEnumerable<Movie> movies) { return movies.Where(m => m is MovieTransfer) .Sum(m => m.Price); } private static int TotalPriceOfMovie(IEnumerable<Movie> movies) { return movies.Where(m => m is Movie) .Sum(m => m.Price); } private static IEnumerable<Movie> GetMovies() { return new List<Movie>() { new Movie(), new MovieTransfer(), new Movie() }; } } public class Movie { public virtual int Price { get { return 2; } } } public class MovieTransfer : Movie { public override int Price { get { return 3; } } } pulbic static class LoopExtensions { public static void ForEach<T>(this IEnumerable<T> values, Action<T> action) { Contract.Requires(values != null); Contract.Requires(action != null); foreach (var v in values) action(v); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } I think the new code is much cleaner than the first one, and I love the ForEach extension on the IEnumerable<T>, I can use it for different kind of things, for example: movies.Where(m => m is Movie) .ForEach(DoSomething); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } By using the Where and ForEach extension method, some if statements can be removed and will make the code much cleaner. But the beauty is in the eye of the beholder. What would you have done different, what do you think will make the first example in the blog post look much cleaner than my results, comments are welcome! If you want to know when I will publish a new blog post, you can follow me on twitter: http://www.twitter.com/fredrikn

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• GD! Converting a png image to jpeg and making the alpha by default white and not black.

  - by Shawn

  I tried something like this but it just makes the background of the image white, not necessarily the alpha of the image. I wanted to just upload everything as jpg's so if i could somehow "flatten" a png image with some transparently to default it to just be white so i can use it as a jpg instead. Appreciate any help. Thanks. $old = imagecreatefrompng($upload); $background = imagecolorallocate($old,255,255,255); imagefill($old, 0, 0, $background); imagealphablending($old, false); imagesavealpha($old, true);

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• How to get Faster RDP

  - by Jay

  We are using Win 2008 R2 and connecting to it from Win7 boxes. The RDP is faster then before but we want to know if their are any other solutions that will make it faster. Due to licensing issue we got a software that multiple people need to access (not all at the same time) and the only way i can find is to install on a server and give RDP access to users. Is their a faster remote desktop tool then RDP ? Thanks Jay

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• Emacs/xterm color annoyance on Linux

  - by tgamblin

  I'm using emacs in a console window both on my local Linux box and on the login node of a remote cluster. I use emacs regularly, and I've got the foreground color set to white in my .emacs file like so: (set-foreground-color "white") (set-background-color "black") However, when I run emacs, the foreground isn't white; it's grey and very hard to read. On my Mac, emacs in a console window with the same settings shows up as proper white. But on both linux boxes, in konsole and xterm, it's grey. In case it matters, I've got TERM set to xterm-color, the desktop is running RHEL 5, and the cluster node is running RHEL 4 (CentOS). Is this some default with how Linux sets up terminal colors? How do I get white to be white? Note: this is with console emacs, not emacs under X. That's emacs -nw if you have DISPLAY set.

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• Build 32-bit with 64-bit llvm-gcc

  - by Jay Conrod

  I have a 64-bit version of llvm-gcc, but I want to be able to build both 32-bit and 64-bit binaries. Is there a flag for this? I tried passing -m32 (which works on the regular gcc), but I get an error message like this: [jay@andesite]$ llvm-gcc -m32 test.c -o test Warning: Generation of 64-bit code for a 32-bit processor requested. Warning: 64-bit processors all have at least SSE2. /tmp/cchzYo9t.s: Assembler messages: /tmp/cchzYo9t.s:8: Error: bad register name `%rbp' /tmp/cchzYo9t.s:9: Error: bad register name `%rsp' ... This is backwards; I want to generate 32-bit code for a 64-bit processor! I'm running llvm-gcc 4.2, the one that comes with Ubuntu 9.04 x86-64. EDIT: Here is the relevant part of the output when I run llvm-gcc with the -v flag: [jay@andesite]$ llvm-gcc -v -m32 test.c -o test.bc Using built-in specs. Target: x86_64-linux-gnu Configured with: ../llvm-gcc4.2-2.2.source/configure --host=x86_64-linux-gnu --build=x86_64-linux-gnu --prefix=/usr/lib/llvm/gcc-4.2 --enable-languages=c,c++ --program-prefix=llvm- --enable-llvm=/usr/lib/llvm --enable-threads --disable-nls --disable-shared --disable-multilib --disable-bootstrap Thread model: posix gcc version 4.2.1 (Based on Apple Inc. build 5546) (LLVM build) /usr/lib/llvm/gcc-4.2/libexec/gcc/x86_64-linux-gnu/4.2.1/cc1 -quiet -v -imultilib . test.c -quiet -dumpbase test.c -m32 -mtune=generic -auxbase test -version -o /tmp/ccw6TZY6.s I looked in /usr/lib/llvm/gcc-4.2/libexec/gcc hoping to find another binary, but the only directory there is x86_64-linux-gnu. I will probably look at compiling llvm-gcc from source with appropriate options next.

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• Inserting THEAD element into embedded HTML using jQuery

  - by robalot

  I'm trying to use jQuery to insert HTML into a table element. I've been messing variations of the selector (below) with no luck. Can someone help me? My Selector: $j('#ctl00_body_gridData_dom').children('table:first').append("<thead><tr><td colspan='6'>&nbsp;</td><td align='center' colspan='7'>EM SPECS</td><td align='center' colspan='7'>FISH</td><td colspan='11'>&nbsp;</td></tr></thead>"); Here's what I am trying to do... I want to insert this: <thead> <tr> <td colspan="6"> &nbsp; </td> <td align="center" colspan="7"> EM SPECS </td> <td align="center" colspan="7"> FISH </td> <td colspan="11"> &nbsp; </td> </tr> </thead> The sample below is what I want the end result to look like... So It Looks Like This: Jquery Event Pool <table id="ctl00_body_gridData" style="width: 2000px; -moz-user-select: none;" border="1" cellpadding="0" cellspacing="0"> <tbody> <tr> <td id="ctl00_body_gridData_dom" class="GridData" style="vertical-align: top; height: 245px;" valign="top"> <table style="width: 100%;" border="0" cellpadding="0" cellspacing="0"> <thead> <tr> <td colspan="6"> &nbsp; </td> <td align="center" colspan="7"> EM SPECS </td> <td align="center" colspan="7"> FISH </td> <td colspan="11"> &nbsp; </td> </tr> </thead> <tbody> <tr id="ctl00_body_gridData_top_head" class="headerlineGrid"> <td width="16"> <div style="width: 16px;"></div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,4,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,4,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,0,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,4,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,4,0)" style="width: 89px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 89px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Work<br>Package</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,6,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,6,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,1,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,6,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,6,0)" style="width: 62px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 62px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Work<br>Order</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,9,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,9,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,2,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,9,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,9,0)" style="width: 66px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 66px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> FCR<br>Group</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,12,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,12,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,3,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,12,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,12,0)" style="width: 105px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 105px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center">Contractor</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,15,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,15,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,4,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,15,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,15,0)" style="width: 159px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 159px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Capital/Expense<br>Group</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,19,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,19,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,5,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,19,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,19,0)" style="width: 99px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 99px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center">Cost Type</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,20,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,20,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,6,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,20,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,20,0)" style="width: 81px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 81px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Commit<br>Dollars</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,21,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,21,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,7,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,21,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,21,0)" style="width: 81px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 81px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Commit<br>Hours</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,22,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,22,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,8,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,22,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,22,0)" style="width: 86px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 86px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Commit<br>Quantity</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,23,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,23,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,9,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,23,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,23,0)" style="width: 76px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 76px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Control<br>Budget</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,24,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,24,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,10,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,24,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,24,0)" style="width: 46px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 46px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center">FTC</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,25,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,25,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,11,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,25,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,25,0)" style="width: 88px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 88px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Total<br>Forecast</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,26,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,26,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,12,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,26,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,26,0)" style="width: 50px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 50px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Ctr<br>COB</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,27,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,27,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,13,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,27,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,27,0)" style="width: 49px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 49px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Ctr<br>CCB</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,28,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,28,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,14,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,28,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,28,0)" style="width: 81px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 81px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Ctr<br> Commit<br>$</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,29,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,29,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,15,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,29,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,29,0)" style="width: 81px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 81px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Ctr<br> Commit<br>Hours</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,30,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,30,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,16,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,30,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,30,0)" style="width: 86px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 86px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Ctr<br> Commit<br>Quantity</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,31,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,31,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,17,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,31,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,31,0)" style="width: 95px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 95px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Ctr<br>% Compl.</td> </tr> </tbody> </table> </div> </td> <td onclick="ctl00_body_gridData.ClickHandler(event,this,32,0)" ondblclick="ctl00_body_gridData.DblClickHandler(event,null,32,0)" onmousemove="ctl00_body_gridData.MoveHandler(event,this,18,0)" onmouseover="ctl00_body_gridData.OverHandler(event,this,0)" onmouseout="ctl00_body_gridData.OutHandler(event,this,0)" onmousedown="ctl00_body_gridData.DownHandler(event,this,32,0)" onmouseup="ctl00_body_gridData.UpHandler(event,this,32,0)" style="width: 105px;" class="HeadingCell" align="center"> <div style="text-align: center; overflow: hidden; width: 105px;"> <table width="100%" border="0" cellpadding="0" cellspacing="0"> <tbody> <tr> <td style="white-space: nowrap; text-align: center;" class="HeadingCellText" align="center"> Contractor<br>CFTC</td> </tr> </tbody> </table> </div> </td> </tr> <tr> <td id="ctl00_body_gridData_expcolgrp_0" width="16" align="center"></td> <td class="GroupHeading" colspan="20"> FCR<br>Group: Engineering</td> </tr> <tr> <td id="ctl00_body_gridData_expcolgrp_1" width="16" align="center"></td> <td class="GroupHeading" colspan="20"> FCR<br>Group: Pipe</td> </tr> <tr> <td id="ctl00_body_gridData_expcolgrp_2" width="16" align="center"></td> <td class="GroupHeading" colspan="20"> FCR<br>Group: Concrete</td> </tr> <tr> <td id="ctl00_body_gridData_expcolgrp_3" width="16" align="center"></td> <td class="GroupHeading" colspan="20"> FCR<br>Group: Insulation</td> </tr> <tr> <td id="ctl00_body_gridData_expcolgrp_4" width="16" align="center"></td> <td class="GroupHeading" colspan="20"> FCR<br>Group: Buildings</td> </tr> </tbody> </table> </td> </tr> </tbody> </table> </body> </html>

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• Design by Contract with Microsoft .Net Code Contract

  - by Fredrik N

  I have done some talks on different events and summits about Defensive Programming and Design by Contract, last time was at Cornerstone’s Developer Summit 2010. Next time will be at SweNug (Sweden .Net User Group). I decided to write a blog post about of some stuffs I was talking about. Users are a terrible thing! Protect your self from them ”Human users have a gift for doing the worst possible thing at the worst possible time.” – Michael T. Nygard, Release It! The kind of users Michael T. Nygard are talking about is the users of a system. We also have users that uses our code, the users I’m going to focus on is the users of our code. Me and you and another developers. “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” – Martin Fowler Good programmers also writes code that humans know how to use, good programmers also make sure software behave in a predictable manner despise inputs or user actions. Design by Contract   Design by Contract (DbC) is a way for us to make a contract between us (the code writer) and the users of our code. It’s about “If you give me this, I promise to give you this”. It’s not about business validations, that is something completely different that should be part of the domain model. DbC is to make sure the users of our code uses it in a correct way, and that we can rely on the contract and write code in a way where we know that the users will follow the contract. It will make it much easier for us to write code with a contract specified. Something like the following code is something we may see often: public void DoSomething(Object value) { value.DoIKnowThatICanDoThis(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Where “value” can be uses directly or passed to other methods and later be used. What some of us can easily forget here is that the “value” can be “null”. We will probably not passing a null value, but someone else that uses our code maybe will do it. I think most of you (including me) have passed “null” into a method because you don’t know if the argument need to be specified to a valid value etc. I bet most of you also have got the “Null reference exception”. Sometimes this “Null reference exception” can be hard and take time to fix, because we need to search among our code to see where the “null” value was passed in etc. Wouldn’t it be much better if we can as early as possible specify that the value can’t not be null, so the users of our code also know it when the users starts to use our code, and before run time execution of the code? This is where DbC comes into the picture. We can use DbC to specify what we need, and by doing so we can rely on the contract when we write our code. So the code above can actually use the DoIKnowThatICanDoThis() method on the value object without being worried that the “value” can be null. The contract between the users of the code and us writing the code, says that the “value” can’t be null.   Pre- and Postconditions   When working with DbC we are specifying pre- and postconditions.  Precondition is a condition that should be met before a query or command is executed. An example of a precondition is: “The Value argument of the method can’t be null”, and we make sure the “value” isn’t null before the method is called. Postcondition is a condition that should be met when a command or query is completed, a postcondition will make sure the result is correct. An example of a postconditon is “The method will return a list with at least 1 item”. Commands an Quires When using DbC, we need to know what a Command and a Query is, because some principles that can be good to follow are based on commands and queries. A Command is something that will not return anything, like the SQL’s CREATE, UPDATE and DELETE. There are two kinds of Commands when using DbC, the Creation commands (for example a Constructor), and Others. Others can for example be a Command to add a value to a list, remove or update a value etc. //Creation commands public Stack(int size) //Other commands public void Push(object value); public void Remove(); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   A Query, is something that will return something, for example an Attribute, Property or a Function, like the SQL’s SELECT.   There are two kinds of Queries, the Basic Queries  (Quires that aren’t based on another queries), and the Derived Queries, queries that is based on another queries. Here is an example of queries of a Stack: //Basic Queries public int Count; public object this[int index] { get; } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To understand about some principles that are good to follow when using DbC, we need to know about the Commands and different Queries. The 6 Principles When working with DbC, it’s advisable to follow some principles to make it easier to define and use contracts. The following DbC principles are: Separate commands and queries. Separate basic queries from derived queries. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries. For each command, write a postcondition that specifies the value of every basic query. For every query and command, decide on a suitable precondition. Write invariants to define unchanging properties of objects. Before I will write about each of them I want you to now that I’m going to use .Net 4.0 Code Contract. I will in the rest of the post uses a simple Stack (Yes I know, .Net already have a Stack class) to give you the basic understanding about using DbC. A Stack is a data structure where the first item in, will be the first item out. Here is a basic implementation of a Stack where not contract is specified yet: public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } //Is related to Count and this[] Query public object Top() { return this[Count]; } //Creation commands public Stack(uint size) { Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { this[++Count] = value; } public void Remove() { this[Count] = null; Count--; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The Stack is implemented in a way to demonstrate the use of Code Contract in a simple way, the implementation may not look like how you would implement it, so don’t think this is the perfect Stack implementation, only used for demonstration.   Before I will go deeper into the principles I will simply mention how we can use the .Net Code Contract. I mention before about pre- and postcondition, is about “Require” something and to “Ensure” something. When using Code Contract, we will use a static class called “Contract” and is located in he “System.Diagnostics.Contracts” namespace. The contract must be specified at the top or our member statement block. To specify a precondition with Code Contract we uses the Contract.Requires method, and to specify a postcondition, we uses the Contract.Ensure method. Here is an example where both a pre- and postcondition are used: public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The contract above requires that the Count is greater than 0, if not we can’t get the item at the Top of a Stack. We also Ensures that the results (By using the Contract.Result method, we can specify a postcondition that will check if the value returned from a method is correct) of the Top query is equal to this[Count].   1. Separate Commands and Queries   When working with DbC, it’s important to separate Command and Quires. A method should either be a command that performs an Action, or returning information to the caller, not both. By asking a question the answer shouldn’t be changed. The following is an example of a Command and a Query of a Stack: public void Push(object value) public object Top() .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The Push is a command and will not return anything, just add a value to the Stack, the Top is a query to get the item at the top of the stack.   2. Separate basic queries from derived queries There are two different kinds of queries,  the basic queries that doesn’t rely on another queries, and derived queries that uses a basic query. The “Separate basic queries from derived queries” principle is about about that derived queries can be specified in terms of basic queries. So this principles is more about recognizing that a query is a derived query or a basic query. It will then make is much easier to follow the other principles. The following code shows a basic query and a derived query: //Basic Queries public uint Count; //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   We can see that IsEmpty will use the Count query, and that makes the IsEmpty a Derived query.   3. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries.   When the derived query is recognize we can follow the 3ed principle. For each derived query, we can create a postcondition that specifies what result our derived query will return in terms of one or more basic queries. Remember that DbC is about contracts between the users of the code and us writing the code. So we can’t use demand that the users will pass in a valid value, we must also ensure that we will give the users what the users wants, when the user is following our contract. The IsEmpty query of the Stack will use a Count query and that will make the IsEmpty a Derived query, so we should now write a postcondition that specified what results will be returned, in terms of using a basic query and in this case the Count query, //Basic Queries public uint Count; //Derived Queries public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } The Contract.Ensures is used to create a postcondition. The above code will make sure that the results of the IsEmpty (by using the Contract.Result to get the result of the IsEmpty method) is correct, that will say that the IsEmpty will be either true or false based on Count is equal to 0 or not. The postcondition are using a basic query, so the IsEmpty is now following the 3ed principle. We also have another Derived Query, the Top query, it will also need a postcondition and it uses all basic queries. The Result of the Top method must be the same value as the this[] query returns. //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count and this[] Query public object Top() { Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   4. For each command, write a postcondition that specifies the value of every basic query.   For each command we will create a postconditon that specifies the value of basic queries. If we look at the Stack implementation we will have three Commands, one Creation command, the Constructor, and two others commands, Push and Remove. Those commands need a postcondition and they should include basic query to follow the 4th principle. //Creation commands public Stack(uint size) { Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   As you can see the Create command will Ensures that Count will be 0 when the Stack is created, when a Stack is created there shouldn’t be any items in the stack. The Push command will take a value and put it into the Stack, when an item is pushed into the Stack, the Count need to be increased to know the number of items added to the Stack, and we must also make sure the item is really added to the Stack. The postconditon of the Push method will make sure the that old value of the Count (by using the Contract.OldValue we can get the value a Query has before the method is called)  plus 1 will be equal to the Count query, this is the way we can ensure that the Push will increase the Count with one. We also make sure the this[] query will now contain the item we pushed into the Stack. The Remove method must make sure the Count is decreased by one when the top item is removed from the Stack. The Commands is now following the 4th principle, where each command now have a postcondition that used the value of basic queries. Note: The principle says every basic Query, the Remove only used one Query the Count, it’s because this command can’t use the this[] query because an item is removed, so the only way to make sure an item is removed is to just use the Count query, so the Remove will still follow the principle.   5. For every query and command, decide on a suitable precondition.   We have now focused only on postcondition, now time for some preconditons. The 5th principle is about deciding a suitable preconditon for every query and command. If we starts to look at one of our basic queries (will not go through all Queries and commands here, just some of them) the this[] query, we can’t pass an index that is lower then 1 (.Net arrays and list are zero based, but not the stack in this blog post ;)) and the index can’t be lesser than the number of items in the stack. So here we will need a preconditon. public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Think about the Contract as an documentation about how to use the code in a correct way, so if the contract could be specified elsewhere (not part of the method body), we could simply write “return _array[index]” and there is no need to check if index is greater or lesser than Count, because that is specified in a “contract”. The implementation of Code Contract, requires that the contract is specified in the code. As a developer I would rather have this contract elsewhere (Like Spec#) or implemented in a way Eiffel uses it as part of the language. Now when we have looked at one Query, we can also look at one command, the Remove command (You can see the whole implementation of the Stack at the end of this blog post, where precondition is added to more queries and commands then what I’m going to show in this section). We can only Remove an item if the Count is greater than 0. So we can write a precondition that will require that Count must be greater than 0. public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   6. Write invariants to define unchanging properties of objects.   The last principle is about making sure the object are feeling great! This is done by using invariants. When using Code Contract we can specify invariants by adding a method with the attribute ContractInvariantMethod, the method must be private or public and can only contains calls to Contract.Invariant. To make sure the Stack feels great, the Stack must have 0 or more items, the Count can’t never be a negative value to make sure each command and queries can be used of the Stack. Here is our invariant for the Stack object: [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The ObjectInvariant method will be called every time after a Query or Commands is called. Here is the full example using Code Contract:   public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } set { Contract.Requires(index >= 1); Contract.Requires(index <= Count); _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } //Is related to Count and this[] Query public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } //Creation commands public Stack(uint size) { Contract.Requires(size > 0); Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Requires(value != null); Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Summary By using Design By Contract we can make sure the users are using our code in a correct way, and we must also make sure the users will get the expected results when they uses our code. This can be done by specifying contracts. To make it easy to use Design By Contract, some principles may be good to follow like the separation of commands an queries. With .Net 4.0 we can use the Code Contract feature to specify contracts.

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• Add logo background color to data returned by StackAuth sites route

  - by Yi Jiang

  Given that now with Stack Exchange 2.0 the logo of some of the sites, like Web Apps, AskUbuntu, Photography, Gaming and Pro Webmasters have non-white background, I think it will be best if the StackAuth sites route can include the preferred background color for those the logo of these sites. This is especially important for sites like Photography whose logo is unreadable if the traditional white is used. Edit: Here's an example of what I mean here: As you can see, the AskUbuntu logo text totally invisible against a white background.

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• Vermeidung von SOA Anti-Patterns mittels AIA

  - by Hans Viehmann

  Gerade ist mir ein White Paper des Enterprise Architecture Teams in die Hände gefallen, das sich mit SOA Anti-Patterns befasst. Es ist zwar kein AIA Paper im eigentlichen Sinne, aber mit AIA hat man natürlich eine gute Unterstützung darin, die dort beschriebenen Fehler zu vermeiden. Das White Paper behandelt Themen wie: Vermeidung von SOA Silos SOA Reifegrad und Projekt-Management Ausuferndes Service Portfolio Umgang mit Referenz-Architekturen EAI 2.0 - Punkt-zu-Punkt Integration auf offenen Standards Ein Link auf das Dokument ist unten angefügt - viel Vergnügen bei der Lektüre ... Oracle White Paper: SOA Anti-Patterns.

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• New Whitepaper: Best Practices for Gathering EBS Database Statistics

  - by Elke Phelps (Oracle Development)

  Most Oracle Applications DBAs and E-Business Suite users understand the importance of accurate database statistics.  Missing, stale or skewed statistics can adversely affect performance.  Oracle E-Business Suite statistics should only be gathered using FND_STATS or the Gather Statistics concurrent request. Gathering statistics with DBMS_STATS or the desupported ANALYZE command may result in suboptimal executions plans for E-Business Suite. Our E-Business Suite Performance Team has been busy implementing and testing new features for gathering statistics using FND_STATS in Oracle E-Business Suite databases.  The new features and guidelines for when and how to gather statistics are published in the following whitepaper: Best Practices for Gathering Statistics with Oracle E-Business Suite (Note 1586374.1) The new white paper details the following options for gathering statistics using FND_STATS and the Gather Statistics concurrent request:: History Mode - backup existing statistics prior to gather new statistics GATHER_AUTO Option - gather statistics for tables based upon % change Histograms - collect statistics for histograms AUTO Sampling - use the new FND_STATS feature that supports the AUTO option for using AUTO sample size Extended Statistics - use the new FND_STATS feature that supports the creation of column groups and automatic statistics collection on the column groups when table statistics are gathered Incremental Statistics - gather incremental statistics for partitioned tables The new white paper also includes examples and performance test cases for the following: Extended Optimizer Statistics Incremental Statistics Gathering Concurrent Statistics Gathering This white paper includes details about the standalone Oracle E-Business Suite Release 11i and 12 patches that are required to take advantage of this new functionality. Your feedback is welcome We would be very interested in hearing about your experiences with these new options for gathering statistics.  Please feel free to post your comments here or drop us a line privately.Related Oracle OpenWorld 2013 Session Getting Optimal Performance from Oracle E-Business Suite (CON8485) Related My Oracle Support Notes Collecting Statistics with Oracle EBS 11i and R12 (Note 368252.1) Non-EBS Related Blogs, White Papers and My Oracle Support Notes  Oracle Optimizer Blog Understanding Optimizer Statistic (white paper) Fixed Objects Statistics(GATHER_FIXED_OBJECTS_STATS) Considerations (Note 798257.1)

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• XNA running slow when making a texture

  - by Anthony

  I'm using XNA to test an image analysis algorithm for a robot. I made a simple 3D world that has a grass, a robot, and white lines (that are represent the course). The image analysis algorithm is a modification of the Hough line detection algorithm. I have the game render 2 camera views to a render target in memory. One camera is a top down view of the robot going around the course, and the second camera is the view from the robot's perspective as it moves along. I take the rendertarget of the robot camera and convert it to a Color[,] so that I can do image analysis on it. private Color[,] TextureTo2DArray(Texture2D texture, Color[] colors1D, Color[,] colors2D) { texture.GetData(colors1D); for (int x = 0; x < texture.Width; x++) { for (int y = 0; y < texture.Height; y++) { colors2D[x, y] = colors1D[x + (y * texture.Width)]; } } return colors2D; } I want to overlay the results of the image analysis on the robot camera view. The first part of the image analysis is finding the white pixels. When I find the white pixels I create a bool[,] array showing which pixels were white and which were black. Then I want to convert it back into a texture so that I can overlay on the robot view. When I try to create the new texture showing which ones pixels were white, then the game goes super slow (around 10 hz). Can you give me some pointers as to what to do to make the game go faster. If I comment out this algorithm, then it goes back up to 60 hz. private Texture2D GenerateTexturesFromBoolArray(bool[,] boolArray,Color[] colorMap, Texture2D textureToModify) { for(int i =0;i < screenWidth;i++) { for(int j =0;j<screenHeight;j++) { if (boolArray[i, j] == true) { colorMap[i+(j*screenWidth)] = Color.Red; } else { colorMap[i + (j * screenWidth)] = Color.Transparent; } } } textureToModify.SetData<Color>(colorMap); return textureToModify; } Each Time I run draw, I must set the texture to null, so that I can modify it. public override void Draw(GameTime gameTime) { Vector2 topRightVector = ((SimulationMain)Game).spriteRectangleManager.topRightVector; Vector2 scaleFactor = ((SimulationMain)Game).config.scaleFactorScreenSizeToWindow; this.spriteBatch.Begin(); // Start the 2D drawing this.spriteBatch.Draw(this.textureFindWhite, topRightVector, null, Color.White, 0, Vector2.Zero, scaleFactor, SpriteEffects.None, 0); this.spriteBatch.End(); // Stop drawing. GraphicsDevice.Textures[0] = null; } Thanks for the help, Anthony G.

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• Working with Microsoft PEX Framework

  Automated white-box testing of .NET applications

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