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  • How do I create an instance of this class in Android?

    - by Lloyd Banks
    I was wondering if it is possible to create an instance of this class (from the link, which creates a listview) from another class so that I can call on either lazyadapter.java or customizedlistview.java (not sure which one) to inflate that same listview. Is this possible? This is what I tried (obviously incorrect): CustomizedListView clv = new CustomizedListView(); clv.onCreate(...); source: http://www.androidhive.info/2012/02/android-custom-listview-with-image-and-text/ LazyAdapter.java import java.util.ArrayList; import java.util.HashMap; import android.app.Activity; import android.content.Context; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.ImageView; import android.widget.TextView; public class LazyAdapter extends BaseAdapter { private Activity activity; private ArrayList&lt;HashMap&lt;String, String&gt;&gt; data; private static LayoutInflater inflater=null; public ImageLoader imageLoader; public LazyAdapter(Activity a, ArrayList&lt;HashMap&lt;String, String&gt;&gt; d) { activity = a; data=d; inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE); imageLoader=new ImageLoader(activity.getApplicationContext()); } public int getCount() { return data.size(); } public Object getItem(int position) { return position; } public long getItemId(int position) { return position; } public View getView(int position, View convertView, ViewGroup parent) { View vi=convertView; if(convertView==null) vi = inflater.inflate(R.layout.list_row, null); TextView title = (TextView)vi.findViewById(R.id.title); // title TextView artist = (TextView)vi.findViewById(R.id.artist); // artist name TextView duration = (TextView)vi.findViewById(R.id.duration); // duration ImageView thumb_image=(ImageView)vi.findViewById(R.id.list_image); // thumb image HashMap&lt;String, String&gt; song = new HashMap&lt;String, String&gt;(); song = data.get(position); // Setting all values in listview title.setText(song.get(CustomizedListView.KEY_TITLE)); artist.setText(song.get(CustomizedListView.KEY_ARTIST)); duration.setText(song.get(CustomizedListView.KEY_DURATION)); imageLoader.DisplayImage(song.get(CustomizedListView.KEY_THUMB_URL), thumb_image); return vi; } } CustomizedListView.java import java.util.ArrayList; import java.util.HashMap; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.NodeList; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.ListView; public class CustomizedListView extends Activity { // All static variables static final String URL = "http://api.androidhive.info/music/music.xml"; // XML node keys static final String KEY_SONG = "song"; // parent node static final String KEY_ID = "id"; static final String KEY_TITLE = "title"; static final String KEY_ARTIST = "artist"; static final String KEY_DURATION = "duration"; static final String KEY_THUMB_URL = "thumb_url"; ListView list; LazyAdapter adapter; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); ArrayList&lt;HashMap&lt;String, String&gt;&gt; songsList = new ArrayList&lt;HashMap&lt;String, String&gt;&gt;(); XMLParser parser = new XMLParser(); String xml = parser.getXmlFromUrl(URL); // getting XML from URL Document doc = parser.getDomElement(xml); // getting DOM element NodeList nl = doc.getElementsByTagName(KEY_SONG); // looping through all song nodes &lt;song&gt; for (int i = 0; i &lt; nl.getLength(); i++) { // creating new HashMap HashMap&lt;String, String&gt; map = new HashMap&lt;String, String&gt;(); Element e = (Element) nl.item(i); // adding each child node to HashMap key =&gt; value map.put(KEY_ID, parser.getValue(e, KEY_ID)); map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE)); map.put(KEY_ARTIST, parser.getValue(e, KEY_ARTIST)); map.put(KEY_DURATION, parser.getValue(e, KEY_DURATION)); map.put(KEY_THUMB_URL, parser.getValue(e, KEY_THUMB_URL)); // adding HashList to ArrayList songsList.add(map); } list=(ListView)findViewById(R.id.list); // Getting adapter by passing xml data ArrayList adapter=new LazyAdapter(this, songsList); list.setAdapter(adapter); // Click event for single list row list.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView&lt;?&gt; parent, View view, int position, long id) { } }); } }

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  • C++: Declaration of template class member specialization (+ Doxygen bonus question!)

    - by Ziv
    When I specialize a (static) member function/constant in a template class, I'm confused as to where the declaration is meant to go. Here's an example of what I what to do - yoinked directly from IBM's reference on template specialization: template<class T> class X { public: static T v; static void f(T); }; template<class T> T X<T>::v = 0; template<class T> void X<T>::f(T arg) { v = arg; } template<> char* X<char*>::v = "Hello"; template<> void X<float>::f(float arg) { v = arg * 2; } int main() { X<char*> a, b; X<float> c; c.f(10); // X<float>::v now set to 20 } The question is, how do I divide this into header/cpp files? The generic implementation is obviously in the header, but what about the specialization? It can't go in the header file, because it's concrete, leading to multiple definition. But if it goes into the .cpp file, is code which calls X::f() aware of the specialization, or might it rely on the generic X::f()? So far I've got the specialization in the .cpp only, with no declaration in the header. I'm not having trouble compiling or even running my code (on gcc, don't remember the version at the moment), and it behaves as expected - recognizing the specialization. But A) I'm not sure this is correct, and I'd like to know what is, and B) my Doxygen documentation comes out wonky and very misleading (more on that in a moment). What seems most natural to me would be something like this, declaring the specialization in the header and defining it in the .cpp: ===XClass.hpp=== #ifndef XCLASS_HPP #define XCLASS_HPP template<class T> class X { public: static T v; static void f(T); }; template<class T> T X<T>::v = 0; template<class T> void X<T>::f(T arg) { v = arg; } /* declaration of specialized functions */ template<> char* X<char*>::v; template<> void X<float>::f(float arg); #endif ===XClass.cpp=== #include <XClass.hpp> /* concrete implementation of specialized functions */ template<> char* X<char*>::v = "Hello"; template<> void X<float>::f(float arg) { v = arg * 2; } ...but I have no idea if this is correct. The most immediate consequence of this issue, as I mentioned, is my Doxygen documentation, which doesn't seem to warm to the idea of member specialization, at least the way I'm defining it at the moment. It will always present only the first definition it finds of a function/constant, and I really need to be able to present the specializations as well. If I go so far as to re-declare the entire class, i.e. in the header: /* template declaration */ template<class T> class X { public: static T v; static void f(T); }; /* template member definition */ template<class T> T X<T>::v = 0; template<class T> void X<T>::f(T arg) { v = arg; } /* declaration of specialized CLASS (with definitions in .cpp) */ template<> class X<float> { public: static float v; static void f(float); }; then it will display the different variations of X as different classes (which is fine by me), but I don't know how to get the same effect when specializing only a few select members of the class. I don't know if this is a mistake of mine, or a limitation of Doxygen - any ideas? Thanks much, Ziv

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  • How to match ColdFusion encryption with Java 1.4.2?

    - by JohnTheBarber
    * sweet - thanks to Edward Smith for the CF Technote that indicated the key from ColdFusion was Base64 encoded. See generateKey() for the 'fix' My task is to use Java 1.4.2 to match the results a given ColdFusion code sample for encryption. Known/given values: A 24-byte key A 16-byte salt (IVorSalt) Encoding is Hex Encryption algorithm is AES/CBC/PKCS5Padding A sample clear-text value The encrypted value of the sample clear-text after going through the ColdFusion code Assumptions: Number of iterations not specified in the ColdFusion code so I assume only one iteration 24-byte key so I assume 192-bit encryption Given/working ColdFusion encryption code sample: <cfset ThisSalt = "16byte-salt-here"> <cfset ThisAlgorithm = "AES/CBC/PKCS5Padding"> <cfset ThisKey = "a-24byte-key-string-here"> <cfset thisAdjustedNow = now()> <cfset ThisDateTimeVar = DateFormat( thisAdjustedNow , "yyyymmdd" )> <cfset ThisDateTimeVar = ThisDateTimeVar & TimeFormat( thisAdjustedNow , "HHmmss" )> <cfset ThisTAID = ThisDateTimeVar & "|" & someOtherData> <cfset ThisTAIDEnc = Encrypt( ThisTAID , ThisKey , ThisAlgorithm , "Hex" , ThisSalt)> My Java 1.4.2 encryption/decryption code swag: package so.example; import java.security.*; import javax.crypto.Cipher; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.SecretKeySpec; import org.apache.commons.codec.binary.*; public class SO_AES192 { private static final String _AES = "AES"; private static final String _AES_CBC_PKCS5Padding = "AES/CBC/PKCS5Padding"; private static final String KEY_VALUE = "a-24byte-key-string-here"; private static final String SALT_VALUE = "16byte-salt-here"; private static final int ITERATIONS = 1; private static IvParameterSpec ivParameterSpec; public static String encryptHex(String value) throws Exception { Key key = generateKey(); Cipher c = Cipher.getInstance(_AES_CBC_PKCS5Padding); ivParameterSpec = new IvParameterSpec(SALT_VALUE.getBytes()); c.init(Cipher.ENCRYPT_MODE, key, ivParameterSpec); String valueToEncrypt = null; String eValue = value; for (int i = 0; i < ITERATIONS; i++) { // valueToEncrypt = SALT_VALUE + eValue; // pre-pend salt - Length > sample length valueToEncrypt = eValue; // don't pre-pend salt Length = sample length byte[] encValue = c.doFinal(valueToEncrypt.getBytes()); eValue = Hex.encodeHexString(encValue); } return eValue; } public static String decryptHex(String value) throws Exception { Key key = generateKey(); Cipher c = Cipher.getInstance(_AES_CBC_PKCS5Padding); ivParameterSpec = new IvParameterSpec(SALT_VALUE.getBytes()); c.init(Cipher.DECRYPT_MODE, key, ivParameterSpec); String dValue = null; char[] valueToDecrypt = value.toCharArray(); for (int i = 0; i < ITERATIONS; i++) { byte[] decordedValue = Hex.decodeHex(valueToDecrypt); byte[] decValue = c.doFinal(decordedValue); // dValue = new String(decValue).substring(SALT_VALUE.length()); // when salt is pre-pended dValue = new String(decValue); // when salt is not pre-pended valueToDecrypt = dValue.toCharArray(); } return dValue; } private static Key generateKey() throws Exception { // Key key = new SecretKeySpec(KEY_VALUE.getBytes(), _AES); // this was wrong Key key = new SecretKeySpec(new BASE64Decoder().decodeBuffer(keyValueString), _AES); // had to un-Base64 the 'known' 24-byte key. return key; } } I cannot create a matching encrypted value nor decrypt a given encrypted value. My guess is it's something to do with how I'm handling the initial vector/salt. I'm not very crypto-savvy but I'm thinking I should be able to take the sample clear-text and produce the same encrypted value in Java as ColdFusion produced. I am able to encrypt/decrypt my own data with my Java code (so I'm consistent) but I cannot match nor decrypt the ColdFusion sample encrypted value. I have access to a local webservice that can test the encrypted output. The given ColdFusion output sample passes/decrypts fine (of course). If I try to decrypt the same sample with my Java code (using the actual key and salt) I get a "Given final block not properly padded" error. I get the same net result when I pass my attempt at encryption (using the actual key and salt) to the test webservice. Any Ideas?

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  • Unable to Calculate Position within Owner-Draw Text

    - by Jonathan Wood
    I'm trying to use Visual Studio 2012 to create a Windows Forms application that can place the caret at the current position within a owner-drawn string. However, I've been unable to find a way to accurately calculate that position. I've done this successfully before in C++. I've now tried numerous methods in C#. Originally, I tried using .NET classes to determine the correct position, but then I tried accessing the Windows API directly. In some cases, I came close, but after some time I still cannot place the caret accurately. I've created a small test program and posted key parts below. I've also posted the entire project here. The exact font used is not important to me; however, my application assumes a mono-spaced font. Any help is appreciated. Form1.cs This is my main form. public partial class Form1 : Form { private string TestString; private int AveCharWidth; private int Position; public Form1() { InitializeComponent(); TestString = "123456789012345678901234567890123456789012345678901234567890"; AveCharWidth = GetFontWidth(); Position = 0; } private void Form1_Load(object sender, EventArgs e) { Font = new Font(FontFamily.GenericMonospace, 12, FontStyle.Regular, GraphicsUnit.Pixel); } protected override void OnGotFocus(EventArgs e) { Windows.CreateCaret(Handle, (IntPtr)0, 2, (int)Font.Height); Windows.ShowCaret(Handle); UpdateCaretPosition(); base.OnGotFocus(e); } protected void UpdateCaretPosition() { Windows.SetCaretPos(Padding.Left + (Position * AveCharWidth), Padding.Top); } protected override void OnLostFocus(EventArgs e) { Windows.HideCaret(Handle); Windows.DestroyCaret(); base.OnLostFocus(e); } protected override void OnPaint(PaintEventArgs e) { e.Graphics.DrawString(TestString, Font, SystemBrushes.WindowText, new PointF(Padding.Left, Padding.Top)); } protected override bool IsInputKey(Keys keyData) { switch (keyData) { case Keys.Right: case Keys.Left: return true; } return base.IsInputKey(keyData); } protected override void OnKeyDown(KeyEventArgs e) { switch (e.KeyCode) { case Keys.Left: Position = Math.Max(Position - 1, 0); UpdateCaretPosition(); break; case Keys.Right: Position = Math.Min(Position + 1, TestString.Length); UpdateCaretPosition(); break; } base.OnKeyDown(e); } protected int GetFontWidth() { int AverageCharWidth = 0; using (var graphics = this.CreateGraphics()) { try { Windows.TEXTMETRIC tm; var hdc = graphics.GetHdc(); IntPtr hFont = this.Font.ToHfont(); IntPtr hOldFont = Windows.SelectObject(hdc, hFont); var a = Windows.GetTextMetrics(hdc, out tm); var b = Windows.SelectObject(hdc, hOldFont); var c = Windows.DeleteObject(hFont); AverageCharWidth = tm.tmAveCharWidth; } catch { } finally { graphics.ReleaseHdc(); } } return AverageCharWidth; } } Windows.cs Here are my Windows API declarations. public static class Windows { [Serializable, StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)] public struct TEXTMETRIC { public int tmHeight; public int tmAscent; public int tmDescent; public int tmInternalLeading; public int tmExternalLeading; public int tmAveCharWidth; public int tmMaxCharWidth; public int tmWeight; public int tmOverhang; public int tmDigitizedAspectX; public int tmDigitizedAspectY; public short tmFirstChar; public short tmLastChar; public short tmDefaultChar; public short tmBreakChar; public byte tmItalic; public byte tmUnderlined; public byte tmStruckOut; public byte tmPitchAndFamily; public byte tmCharSet; } [DllImport("user32.dll")] public static extern bool CreateCaret(IntPtr hWnd, IntPtr hBitmap, int nWidth, int nHeight); [DllImport("User32.dll")] public static extern bool SetCaretPos(int x, int y); [DllImport("User32.dll")] public static extern bool DestroyCaret(); [DllImport("User32.dll")] public static extern bool ShowCaret(IntPtr hWnd); [DllImport("User32.dll")] public static extern bool HideCaret(IntPtr hWnd); [DllImport("gdi32.dll", CharSet = CharSet.Auto)] public static extern bool GetTextMetrics(IntPtr hdc, out TEXTMETRIC lptm); [DllImport("gdi32.dll")] public static extern IntPtr SelectObject(IntPtr hdc, IntPtr hgdiobj); [DllImport("GDI32.dll")] public static extern bool DeleteObject(IntPtr hObject); }

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  • Compile time Meta-programming, with string literals.

    - by Hassan Syed
    I'm writing some code which could really do with some simple compile time metaprogramming. It is common practise to use empty-struct tags as compile time symbols. I need to decorate the tags with some run-time config elements. static variables seem the only way to go (to enable meta-programming), however static variables require global declarations. to side step this Scott Myers suggestion (from the third edition of Effective C++), about sequencing the initialization of static variables by declaring them inside a function instead of as class variables, came to mind. So I came up with the following code, my hypothesis is that it will let me have a compile-time symbols with string literals use-able at runtime. I'm not missing anything I hope. template<class Instance> class TheBestThing { public: void set_name(const char * name_in) { get_name() = std::string(name_in); } void set_fs_location(const char * fs_location_in) { get_fs_location() = std::string(fs_location_in); } std::string & get_fs_location() { static std::string fs_location; return fs_location; } std::string & get_name() { static std::string name; return name; } }; struct tag {}; int main() { TheBestThing<tag> x; x.set_name("xyz"); x.set_fs_location("/etc/lala"); ImportantObject<x> SinceSlicedBread; }

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  • Java Memory Model: reordering and concurrent locks

    - by Steffen Heil
    Hi The java meomry model mandates that synchronize blocks that synchronize on the same monitor enforce a before-after-realtion on the variables modified within those blocks. Example: // in thread A synchronized( lock ) { x = true; } // in thread B synchronized( lock ) { System.out.println( x ); } In this case it is garanteed that thread B will see x==true as long as thread A already passed that synchronized-block. Now I am in the process to rewrite lots of code to use the more flexible (and said to be faster) locks in java.util.concurrent, especially the ReentrantReadWriteLock. So the example looks like this: // in thread A synchronized( lock ) { lock.writeLock().lock(); x = true; lock.writeLock().unlock(); } // in thread B synchronized( lock ) { lock.readLock().lock(); System.out.println( x ); lock.readLock().unlock(); } However, I have not seen any hints within the memory model specification that such locks also imply the nessessary ordering. Looking into the implementation it seems to rely on the access to volatile variables inside AbstractQueuedSynchronizer (for the sun implementation at least). However this is not part of any specification and moreover access to non-volatile variables is not really condsidered covered by the memory barrier given by these variables, is it? So, here are my questions: Is it safe to assume the same ordering as with the "old" synchronized blocks? Is this documented somewhere? Is accessing any volatile variable a memory barrier for any other variable? Regards, Steffen

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  • How to implement Excel Solver functionality in C#?

    - by Vic
    Hi, I have an application in C#, I need to do some optimization calculations, like Excel Solver Add-in does, one option is certainly to write my own solver implementation, but I'm kind of short of time, so I'm looking into libraries that already exist that can help me with this. I've been trying the Microsoft Solver Foundation, which seems pretty neat and cool, the problem is that it doesn't seem to work with the kind of calculations that I need to do. At the end of this question I'm adding the information about the calculations I need to perform and optimize. So basically my question is if any of you know of any other library that I can use for this purpose, or any tutorial that can help to do my own solver, or any idea that gives me a lead to solve this issue. Thanks. Additional Info: This is the data I need to calculate: I have 7 variables, lets call them var1, var2,...,var7 The constraints for these variables are: All of them need to be 0 <= varn <= 0.5 (where n is the number of the variable) The sum of all the variables should be equal to 1 The objective is to maximize the target formula, which in Excel looks like this: (MMULT(TRANSPOSE(L26:L32),M14:M20)) / (SQRT(MMULT(MMULT(TRANSPOSE(L26:L32),M4:S10),L26:L32))) The range that you see in this formula, L26:L32, is actually the range with the variables from above, var1, var2,..., varn. M14:M20 and M4:S10 are ranges with data that I get from different sources, there are more likely decimal values. As I said before, I was using Microsoft Solver Foundation, I modeled pretty much everything with it, I created functions that handle the operations of the target formula, but when I tried to solve the model it always fail, I think it is because of the complexity of the operations. In any case, I just wanted to show these data so you can have an idea about the kind of calculations that I need to implement.

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  • Javascript scope chain

    - by Geromey
    Hi, I am trying to optimize my program. I think I understand the basics of closure. I am confused about the scope chain though. I know that in general you want a low scope (to access variables quickly). Say I have the following object: var my_object = (function(){ //private variables var a_private = 0; return{ //public //public variables a_public : 1, //public methods some_public : function(){ debugger; alert(this.a_public); alert(a_private); }; }; })(); My understanding is that if I am in the some_public method I can access the private variables faster than the public ones. Is this correct? My confusion comes with the scope level of this. When the code is stopped at debugger, firebug shows the public variable inside the this keyword. The this word is not inside a scope level. How fast is accessing this? Right now I am storing any this.properties as another local variable to avoid accessing it multiple times. Thanks very much!

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  • Drop Down Box and other stuff in ASP.NET with VB.NET (VS 2008)

    - by typoknig
    Hi all, I am trying to polish up a program a program that I have converted from a Windows Form in to an ASP.NET Web Application. I have several questions: 1.) I have a drop down box where users can select their variables, but users can also enter their variables manually into various text fields. What I want is for the drop down box to show a string like "Choose Variables" when ever the user enters their variables manually. I want this to happen without having to reload the page. 2.) In the Windows Form version of this application I had a RichTextBox that populated with data (line by line) after a calculation was made. I used "AppendText" in my Windows Form, but that is not available in ASP.NET, and neither is the RichTextBox. I am open to suggestions here, I tried to use just a text box but that isn't working right. 3.) In my Windows Form application I was using "KeyPress" events to prevent incorrect characters from being entered into the text fields. My code for these events looked similar to this: Private Sub TextBox_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox.KeyPress If (e.KeyChar < "0" OrElse e.KeyChar > "9") AndAlso e.KeyChar <> ControlChars.Back AndAlso e.KeyChar <> "." Then e.Handled = True End If End Sub How can I make this work again... also without reloading the page. 4.) This is not a major issue, but I would like all of the text to be selected when the cursor enters a field. In my Windows Form application I used "SelectAll", but again, that is not available in ASP.NET Thanks in advanced.

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  • How to set up django-admin.py on windos vista?

    - by shin
    I manage to install Django after some struggles by using setup.py install on Windows Vista Now I tried to use django-admin.py but it is not working. According to this document, http://docs.djangoproject.com/en/dev/ref/django-admin/ The django-admin.py script should be on your system path if you installed Django via its setup.py utility. If it’s not on your path, ... For Windows users, who do not have symlinking functionality available, you can copy django-admin.py to a location on your existing path or edit the PATH settings (under Settings - Control Panel - System - Advanced - Environment...) to point to its installed location. I checked ComputerpropertiesEnvironment Variables, but path to django-admin.py is not in anywhere. So I added C:\Python25\Lib\site-packages\django\bin which is the folder of django-admin.py in User variables for shin Variable PATH, Value C:\Program Files\Google\google_appengine\;C:\Python25\Lib\site-packages\django\bin\ Am I supposed to add to System variables?? But it still does not work. Could anyone tell me how to add the Path in Environment Variables please? Thanks in advance.

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  • Truly declarative language?

    - by gjvdkamp
    Hi all, Does anyone know of a truly declarative language? The behaviour I'm looking for is kind of what Excel does, where I can define variables and formulas, and have the formula's result change when the input changes (without having set the answer again myself) The behaviour I'm looking for is best shown with this pseudo code: X = 10 // define and assign two variables Y = 20; Z = X + Y // declare a formula that uses these two variables X = 50 // change one of the input variables ?Z // asking for Z should now give 70 (50 + 20) I've tried this in a lot of languages like F#, python, matlab etc, but every time i try this they come up with 30 instead of 70. Wich is correct from an imperative point of view, but i'm looking for a more declerative behaviour if you know what i mean. And this is just a very simple calculation. When things get more difficult it should handle stuff like recursion and memoization automagically. The code below would obviously work in C# but it's just so much code for the job, i'm looking for something a bit more to the point without all that 'technical noise' class BlaBla{ public int X {get;set;} // this used to be even worse before 3.0 public int Y {get;set;} public int Z {get{return X + Y;}} } static void main(){ BlaBla bla = new BlaBla(); bla.X = 10; bla.Y = 20; // can't define anything here bla.X = 50; // bit pointless here but I'll do it anyway. Console.Writeline(bla.Z);// 70, hurray! } This just seems like so much code, curly braces and semicolons that add nothing. Is there a language/ application (apart from Exel) that does this? Maybe I'm no doing it right in the mentioned langauges, or I've completely missed an app that does just this. I prototyped a language/ application that does this (along with some other stuff) and am thinking of productizing it. I just can't believe it's not there yet. Don't want to waste my time. Thanks in advance, Gert-Jan

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  • How to set up django-admin.py on windows vista?

    - by shin
    I manage to install Django after some struggles by using setup.py install on Windows Vista Now I tried to use django-admin.py but it is not working. According to this document, http://docs.djangoproject.com/en/dev/ref/django-admin/ The django-admin.py script should be on your system path if you installed Django via its setup.py utility. If it’s not on your path, ... For Windows users, who do not have symlinking functionality available, you can copy django-admin.py to a location on your existing path or edit the PATH settings (under Settings - Control Panel - System - Advanced - Environment...) to point to its installed location. I checked ComputerpropertiesEnvironment Variables, but path to django-admin.py is not in anywhere. So I added C:\Python25\Lib\site-packages\django\bin which is the folder of django-admin.py in User variables for shin Variable PATH, Value C:\Program Files\Google\google_appengine\;C:\Python25\Lib\site-packages\django\bin\ Am I supposed to add to System variables?? But it still does not work. Could anyone tell me how to add the Path in Environment Variables please? Thanks in advance.

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  • Passing data between Drupal module callback, preprocess and template

    - by rob5408
    I've create a module called finder that I want to take parameters from a url, crunch them and then display results via a tpl file. here's the relevant functions... function finder_menu() { $items = array(); $items['finder'] = array( 'page callback' => 'finder_view', 'access callback' => TRUE, ); return $items; } function finder_theme($existing, $type, $theme, $path) { return array( 'finder_view' => array( 'variables' => array('providers' => null), 'template' => 'results', ), ); } function finder_preprocess_finder_view(&$variables) { // put my data into $variables } function finder_view($zipcode = null) { // Get Providers from Zipcode return theme('finder_view', $providers); } Now I know finder_view is being called. I also know finder_preprocess_finder_view is being called. Finally, I know that result.tpl.php is being used to output. But I cannot wrap my head around how to do meaningful work in the callback, somehow make that data available in the preprocessor to add to "variables" so that i can access in the tpl file. in a situation where you are using a tpl file is the callback even useful for anything? I've done this in the past where the callback does all the work and passes to a theming function, but i want to use a file for output instead this time. Thanks...

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  • Use Zip to Pre-Populate City/State Form with jQuery AJAX

    - by Paul
    I'm running into a problem that I can solve fine by just submitting a form and calling a db to retrieve/echo the information, but AJAX seems to be a bit different for doing this (and is what I need). Earlier in a form process I ask for the zip code like so: <input type="text" maxlength="5" size="5" id="zip" /> Then I have a button to continue, but this button just runs a javascript function that shows the rest of the form. When the rest of the form shows, I want to pre-populate the City input with their city, and pre-populate the State dropdown with their state. I figured I would have to find a way to set city/state to variables, and echo the variables into the form. But I can't figure out how to get/set those variables with AJAX as opposed to a form submit. Here's how I did it without ajax: $zip = mysql_real_escape_string($_POST['zip']); $q = " SELECT city FROM citystatezip WHERE zip = $zip"; $r = mysql_query($q); $row = mysql_fetch_assoc($r); $city = $row['city']; Can anybody help me out with using AJAX to set these variables? Thanks!

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  • Calling arrays from other methods in a different class

    - by Jake H
    Hello, I need help dealing with an array in my java program. in my first class, "test", I set 4 variables and then send them to my other class (test2). arr[i] = new test2(id, fname, lname, case); at that point, variables are set and then I want to return those variables. So in the test2 class, I have a method that strictly returns one of those variables public int getId(){ return id; } I understand this is a little stupid, but professor gets what professor wants I guess. What I want to do now is in my main method in "test" I want to retrieve that variable and sort the array based on that int. Unfortunately, I have to create my own sort function, but I think this would work for what I want to do. for(j = 0; j < arr.length; j++){ int indexMin =j; for(i = j; i < arr.length;i++){ if(arr[i] < arr[indexMin]){ indexMin = i; } } int tmp = arr[j]; arr[j] = arr[indexMin]; arr[indexMin] = tmp; } I appreciate any help anyone could provide. Thank you

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  • Dimension Reduction in Categorical Data with missing values

    - by user227290
    I have a regression model in which the dependent variable is continuous but ninety percent of the independent variables are categorical(both ordered and unordered) and around thirty percent of the records have missing values(to make matters worse they are missing randomly without any pattern, that is, more that forty five percent of the data hava at least one missing value). There is no a priori theory to choose the specification of the model so one of the key tasks is dimension reduction before running the regression. While I am aware of several methods for dimension reduction for continuous variables I am not aware of a similar statical literature for categorical data (except, perhaps, as a part of correspondence analysis which is basically a variation of principal component analysis on frequency table). Let me also add that the dataset is of moderate size 500000 observations with 200 variables. I have two questions. Is there a good statistical reference out there for dimension reduction for categorical data along with robust imputation (I think the first issue is imputation and then dimension reduction)? This is linked to implementation of above problem. I have used R extensively earlier and tend to use transcan and impute function heavily for continuous variables and use a variation of tree method to impute categorical values. I have a working knowledge of Python so if something is nice out there for this purpose then I will use it. Any implementation pointers in python or R will be of great help. Thank you.

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  • Analyzing an IronPython Scope

    - by Vercinegetorix
    I'm trying to write C# code with an embedded IronPython script. Then want to analyze the contents of the script, i.e. list all variables, functions, class and their members/methods. There's an easy way to start, assuming I've got a scope defined and code executed in it already: dynamic variables=pyScope.GetVariables(); foreach (string v in variables) { dynamic dynamicV=pyScope.GetVariable(); /*seems to return everything. variables, functions, classes, instances of classes*/ } But how do I figure out what the type of a variable is? For the following python 'objects', dynamicV.GetType() will return different values: x=5 --system.Int32 y="asdf" --system.String def func():... --IronPython.Runtime.PythonFunction z=class() -- IronPython.Runtime.Types.OldInstance, how can I identify what the actual python class is? class NewClass -- throws an error, GetType() is unavailable. This is almost what I'm looking for. I could capture the exception thrown when unavailable and assume it's a class declaration, but that seems unclean. Is there a better approach? To discover the members/methods of a class it looks like I can use: ObjectOperations op = pyEngine.Operations; object instance = op.Call("className"); foreach (string j in op.GetMemberNames("className")) { object member=op.GetMember(instance, j); Console.WriteLine(member.GetType()); /*once again, GetType() provides some info about the type of the member, but returns null sometimes*/ } Also, how do I get the parameters to a method? Thanks!

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  • F# ref-mutable vars vs object fields

    - by rwallace
    I'm writing a parser in F#, and it needs to be as fast as possible (I'm hoping to parse a 100 MB file in less than a minute). As normal, it uses mutable variables to store the next available character and the next available token (i.e. both the lexer and the parser proper use one unit of lookahead). My current partial implementation uses local variables for these. Since closure variables can't be mutable (anyone know the reason for this?) I've declared them as ref: let rec read file includepath = let c = ref ' ' let k = ref NONE let sb = new StringBuilder() use stream = File.OpenText file let readc() = c := stream.Read() |> char // etc I assume this has some overhead (not much, I know, but I'm trying for maximum speed here), and it's a little inelegant. The most obvious alternative would be to create a parser class object and have the mutable variables be fields in it. Does anyone know which is likely to be faster? Is there any consensus on which is considered better/more idiomatic style? Is there another option I'm missing?

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  • Proper Memory Management for Objective-C Method

    - by Justin
    Hi, I'm programming an iPhone app and I had a question about memory management in one of my methods. I'm still a little new to managing memory manually, so I'm sorry if this question seems elementary. Below is a method designed to allow a number pad to place buttons in a label based on their tag, this way I don't need to make a method for each button. The method works fine, I'm just wondering if I'm responsible for releasing any of the variables I make in the function. The application crashes if I try to release any of the variables, so I'm a little confused about my responsibility regarding memory. Here's the method: FYI the variable firstValue is my label, it's the only variable not declared in the method. -(IBAction)inputNumbersFromButtons:(id)sender { UIButton *placeHolderButton = [[UIButton alloc] init]; placeHolderButton = sender; NSString *placeHolderString = [[NSString alloc] init]; placeHolderString = [placeHolderString stringByAppendingString:firstValue.text]; NSString *addThisNumber = [[NSString alloc] init]; int i = placeHolderButton.tag; addThisNumber = [NSString stringWithFormat:@"%i", i]; NSString *newLabelText = [[NSString alloc] init]; newLabelText = [placeHolderString stringByAppendingString:addThisNumber]; [firstValue setText:newLabelText]; //[placeHolderButton release]; //[placeHolderString release]; //[addThisNumber release]; //[newLabelText release]; } The application works fine with those last four lines commented out, but it seems to me like I should be releasing these variables here. If I'm wrong about that I'd welcome a quick explanation about when it's necessary to release variables declared in functions and when it's not. Thanks.

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  • Javascript Namespace Help

    - by Jason
    Hi, I have a pretty big Javascript script with loads of global variables & functions in it. Then a piece of code that calls one function from this js file: myfunc(); Ok, now I have cloned this script and modified some functionality, all function prototypes and variables are named the same in both scripts. So now I have two scripts loaded and one call to myfunc(), now we have a clash because there are loads of global variables with the same names and two myfunc()s. What I want to do is wrap this cloned script in a namespace, so that I can modify the original call to: clone.myfunc() which will call the new function, but I also want myfunc() to just refer to the original script. In other words I can't touch the original script (no permissions) and I want to be able to use both the clone and the original at runtime. This is the script im cloning: http://pastebin.com/6KR5T3Ah Javascript namespaces seem quite tricky this seems a nice namespace method: var namespace = { foo: function() { } bar: function() { } } ... namespace.foo(); } However that requires using an object, and the script (as posted above) is humongous at nearly 4000 lines, too much to objectize I think? Anyone know a better solution to avoid namespace pollution, with one script I cant touch and one being a clone of that script. Just so I can call myfunc() and clone.myfunc() and all global variables will behave in their respected scope. It's either that, or I go through and modify everything to have unique names, which may take a lifetime This is a Mozilla addon if it helps context wise. Thanks.

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  • Database (MySQL) structuring: pros and cons of multiple tables

    - by Gideon
    I am collecting data and storing it MySQL, for: 75 variables 55 countries Each year I have, at this stage since I am building this tool created a single table, of variables / countries (storing 1 year worth of data). Next year (and for several years after that) a new set of data will be input for each country. There are therefore 3 variables in controlling data returned to a user reviewing all collected data. The general form of any query would be: Show me these specifics variables, for these specific countries, for these specific years. (Show me average age and weight, for USA and Canada, for 2012 and 2009, for example) My question is, it seems that I have two options for arranging this data: -Multiple tables where I create a table of country / variable for each year data is collected - Single table and simply add a column (field) for the year that data relates to. As far as I can tell I could make these database calls with either sructure, but is one more powerful / efficient / quicker, and why? Thanks for your consideration. It's a PDO / PHP interface if that is relevent.

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  • javafx tableview get selected data from ObservableList

    - by user3717821
    i am working on a javafx project and i need your help . while i am trying to get selected data from table i can get selected data from normal cell but can't get data from ObservableList inside tableview. code for my database: -- phpMyAdmin SQL Dump -- version 4.0.4 -- http://www.phpmyadmin.net -- -- Host: localhost -- Generation Time: Jun 10, 2014 at 06:20 AM -- Server version: 5.1.33-community -- PHP Version: 5.4.12 SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO"; SET time_zone = "+00:00"; /*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */; /*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */; /*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */; /*!40101 SET NAMES utf8 */; -- -- Database: `test` -- -- -------------------------------------------------------- -- -- Table structure for table `customer` -- CREATE TABLE IF NOT EXISTS `customer` ( `col0` int(11) NOT NULL, `col1` varchar(255) DEFAULT NULL, `col2` int(11) DEFAULT NULL, PRIMARY KEY (`col0`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; -- -- Dumping data for table `customer` -- INSERT INTO `customer` (`col0`, `col1`, `col2`) VALUES (12, 'adasdasd', 231), (22, 'adasdasd', 231), (212, 'adasdasd', 231); /*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */; /*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */; /*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */; my javafx codes: import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.util.Map; import javafx.application.Application; import javafx.beans.property.SimpleStringProperty; import javafx.beans.value.ChangeListener; import javafx.beans.value.ObservableValue; import javafx.collections.FXCollections; import javafx.collections.ObservableList; import javafx.event.ActionEvent; import javafx.event.EventHandler; import javafx.scene.Scene; import javafx.scene.control.Button; import javafx.scene.control.TableCell; import javafx.scene.control.TableColumn; import javafx.scene.control.TableColumn.CellDataFeatures; import javafx.scene.control.TablePosition; import javafx.scene.control.TableView; import javafx.scene.control.TableView.TableViewSelectionModel; import javafx.scene.control.cell.ChoiceBoxTableCell; import javafx.scene.control.cell.TextFieldTableCell; import javafx.scene.layout.BorderPane; import javafx.stage.Stage; import javafx.util.Callback; import javafx.util.StringConverter; class DBConnector { private static Connection conn; private static String url = "jdbc:mysql://localhost/test"; private static String user = "root"; private static String pass = "root"; public static Connection connect() throws SQLException{ try{ Class.forName("com.mysql.jdbc.Driver").newInstance(); }catch(ClassNotFoundException cnfe){ System.err.println("Error: "+cnfe.getMessage()); }catch(InstantiationException ie){ System.err.println("Error: "+ie.getMessage()); }catch(IllegalAccessException iae){ System.err.println("Error: "+iae.getMessage()); } conn = DriverManager.getConnection(url,user,pass); return conn; } public static Connection getConnection() throws SQLException, ClassNotFoundException{ if(conn !=null && !conn.isClosed()) return conn; connect(); return conn; } } public class DynamicTable extends Application{ Object newValue; //TABLE VIEW AND DATA private ObservableList<ObservableList> data; private TableView<ObservableList> tableview; //MAIN EXECUTOR public static void main(String[] args) { launch(args); } //CONNECTION DATABASE public void buildData(){ tableview.setEditable(true); Callback<TableColumn<Map, String>, TableCell<Map, String>> cellFactoryForMap = new Callback<TableColumn<Map, String>, TableCell<Map, String>>() { @Override public TableCell call(TableColumn p) { return new TextFieldTableCell(new StringConverter() { @Override public String toString(Object t) { return t.toString(); } @Override public Object fromString(String string) { return string; } }); } }; Connection c ; data = FXCollections.observableArrayList(); try{ c = DBConnector.connect(); //SQL FOR SELECTING ALL OF CUSTOMER String SQL = "SELECT * from CUSTOMer"; //ResultSet ResultSet rs = c.createStatement().executeQuery(SQL); /********************************** * TABLE COLUMN ADDED DYNAMICALLY * **********************************/ for(int i=0 ; i<rs.getMetaData().getColumnCount(); i++){ //We are using non property style for making dynamic table final int j = i; TableColumn col = new TableColumn(rs.getMetaData().getColumnName(i+1)); if(j==1){ final ObservableList<String> logLevelList = FXCollections.observableArrayList("FATAL", "ERROR", "WARN", "INFO", "INOUT", "DEBUG"); col.setCellFactory(ChoiceBoxTableCell.forTableColumn(logLevelList)); tableview.getColumns().addAll(col); } else{ col.setCellValueFactory(new Callback<CellDataFeatures<ObservableList,String>,ObservableValue<String>>(){ public ObservableValue<String> call(CellDataFeatures<ObservableList, String> param) { return new SimpleStringProperty(param.getValue().get(j).toString()); } }); tableview.getColumns().addAll(col); } if(j!=1) col.setCellFactory(cellFactoryForMap); System.out.println("Column ["+i+"] "); } /******************************** * Data added to ObservableList * ********************************/ while(rs.next()){ //Iterate Row ObservableList<String> row = FXCollections.observableArrayList(); for(int i=1 ; i<=rs.getMetaData().getColumnCount(); i++){ //Iterate Column row.add(rs.getString(i)); } System.out.println("Row [1] added "+row ); data.add(row); } //FINALLY ADDED TO TableView tableview.setItems(data); }catch(Exception e){ e.printStackTrace(); System.out.println("Error on Building Data"); } } @Override public void start(Stage stage) throws Exception { //TableView Button showDataButton = new Button("Add"); showDataButton.setOnAction(new EventHandler<ActionEvent>() { public void handle(ActionEvent event) { ObservableList<String> row = FXCollections.observableArrayList(); for(int i=1 ; i<=3; i++){ //Iterate Column row.add("asdasd"); } data.add(row); //FINALLY ADDED TO TableView tableview.setItems(data); } }); tableview = new TableView(); buildData(); //Main Scene BorderPane root = new BorderPane(); root.setCenter(tableview); root.setBottom(showDataButton); Scene scene = new Scene(root,500,500); stage.setScene(scene); stage.show(); tableview.getSelectionModel().selectedItemProperty().addListener(new ChangeListener() { @Override public void changed(ObservableValue observableValue, Object oldValue, Object newValue) { //Check whether item is selected and set value of selected item to Label if (tableview.getSelectionModel().getSelectedItem() != null) { TableViewSelectionModel selectionModel = tableview.getSelectionModel(); ObservableList selectedCells = selectionModel.getSelectedCells(); TablePosition tablePosition = (TablePosition) selectedCells.get(0); Object val = tablePosition.getTableColumn().getCellData(newValue); System.out.println("Selected Value " + val); System.out.println("Selected row " + newValue); } } }); } } please help me..

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  • Creating packages in code - Package Configurations

    Continuing my theme of building various types of packages in code, this example shows how to building a package with package configurations. Incidentally it shows you how to add a variable, and a connection too. It covers the five most common configurations: Configuration File Indirect Configuration File SQL Server Indirect SQL Server Environment Variable  For a general overview try the SQL Server Books Online Package Configurations topic. The sample uses a a simple helper function ApplyConfig to create or update a configuration, although in the example we will only ever create. The most useful knowledge is the configuration string (Configuration.ConfigurationString) that you need to set. Configuration Type Configuration String Description Configuration File The full path and file name of an XML configuration file. The file can contain one or more configuration and includes the target path and new value to set. Indirect Configuration File An environment variable the value of which contains full path and file name of an XML configuration file as per the Configuration File type described above. SQL Server A three part configuration string, with each part being quote delimited and separated by a semi-colon. -- The first part is the connection manager name. The connection tells you which server and database to look for the configuration table. -- The second part is the name of the configuration table. The table is of a standard format, use the Package Configuration Wizard to help create an example, or see the sample script files below. The table contains one or more rows or configuration items each with a target path and new value. -- The third and final part is the optional filter name. A configuration table can contain multiple configurations, and the filter is  literal value that can be used to group items together and act as a filter clause when configurations are being read. If you do not need a filter, just leave the value empty. Indirect SQL Server An environment variable the value of which is the three part configuration string as per the SQL Server type described above. Environment Variable An environment variable the value of which is the value to set in the package. This is slightly different to the other examples as the configuration definition in the package also includes the target information. In our ApplyConfig function this is the only example that actually supplies a target value for the Configuration.PackagePath property. The path is an XPath style path for the target property, \Package.Variables[User::Variable].Properties[Value], the equivalent of which can be seen in the screenshot below, with the object being our variable called Variable, and the property to set is the Value property of that variable object. The configurations as seen when opening the generated package in BIDS: The sample code creates the package, adds a variable and connection manager, enables configurations, and then adds our example configurations. The package is then saved to disk, useful for checking the package and testing, before finally executing, just to prove it is valid. There are some external resources used here, namely some environment variables and a table, see below for more details. namespace Konesans.Dts.Samples { using System; using Microsoft.SqlServer.Dts.Runtime; public class PackageConfigurations { public void CreatePackage() { // Create a new package Package package = new Package(); package.Name = "ConfigurationSample"; // Add a variable, the target for our configurations package.Variables.Add("Variable", false, "User", 0); // Add a connection, for SQL configurations // Add the SQL OLE-DB connection ConnectionManager connectionManagerOleDb = package.Connections.Add("OLEDB"); connectionManagerOleDb.Name = "SQLConnection"; connectionManagerOleDb.ConnectionString = "Provider=SQLOLEDB.1;Data Source=(local);Initial Catalog=master;Integrated Security=SSPI;"; // Add our example configurations, first must enable package setting package.EnableConfigurations = true; // Direct configuration file, see sample file this.ApplyConfig(package, "Configuration File", DTSConfigurationType.ConfigFile, "C:\\Temp\\XmlConfig.dtsConfig", string.Empty); // Indirect configuration file, the emvironment variable XmlConfigFileEnvironmentVariable // contains the path to the configuration file, e.g. C:\Temp\XmlConfig.dtsConfig this.ApplyConfig(package, "Indirect Configuration File", DTSConfigurationType.IConfigFile, "XmlConfigFileEnvironmentVariable", string.Empty); // Direct SQL Server configuration, uses the SQLConnection package connection to read // configurations from the [dbo].[SSIS Configurations] table, with a filter of "SampleFilter" this.ApplyConfig(package, "SQL Server", DTSConfigurationType.SqlServer, "\"SQLConnection\";\"[dbo].[SSIS Configurations]\";\"SampleFilter\";", string.Empty); // Indirect SQL Server configuration, the environment variable "SQLServerEnvironmentVariable" // contains the configuration string e.g. "SQLConnection";"[dbo].[SSIS Configurations]";"SampleFilter"; this.ApplyConfig(package, "Indirect SQL Server", DTSConfigurationType.ISqlServer, "SQLServerEnvironmentVariable", string.Empty); // Direct environment variable, the value of the EnvironmentVariable environment variable is // applied to the target property, the value of the "User::Variable" package variable this.ApplyConfig(package, "EnvironmentVariable", DTSConfigurationType.EnvVariable, "EnvironmentVariable", "\\Package.Variables[User::Variable].Properties[Value]"); #if DEBUG // Save package to disk, DEBUG only new Application().SaveToXml(String.Format(@"C:\Temp\{0}.dtsx", package.Name), package, null); Console.WriteLine(@"C:\Temp\{0}.dtsx", package.Name); #endif // Execute package package.Execute(); // Basic check for warnings foreach (DtsWarning warning in package.Warnings) { Console.WriteLine("WarningCode : {0}", warning.WarningCode); Console.WriteLine(" SubComponent : {0}", warning.SubComponent); Console.WriteLine(" Description : {0}", warning.Description); Console.WriteLine(); } // Basic check for errors foreach (DtsError error in package.Errors) { Console.WriteLine("ErrorCode : {0}", error.ErrorCode); Console.WriteLine(" SubComponent : {0}", error.SubComponent); Console.WriteLine(" Description : {0}", error.Description); Console.WriteLine(); } package.Dispose(); } /// <summary> /// Add or update an package configuration. /// </summary> /// <param name="package">The package.</param> /// <param name="name">The configuration name.</param> /// <param name="type">The type of configuration</param> /// <param name="setting">The configuration setting.</param> /// <param name="target">The target of the configuration, leave blank if not required.</param> internal void ApplyConfig(Package package, string name, DTSConfigurationType type, string setting, string target) { Configurations configurations = package.Configurations; Configuration configuration; if (configurations.Contains(name)) { configuration = configurations[name]; } else { configuration = configurations.Add(); } configuration.Name = name; configuration.ConfigurationType = type; configuration.ConfigurationString = setting; configuration.PackagePath = target; } } } The following table lists the environment variables required for the full example to work along with some sample values. Variable Sample value EnvironmentVariable 1 SQLServerEnvironmentVariable "SQLConnection";"[dbo].[SSIS Configurations]";"SampleFilter"; XmlConfigFileEnvironmentVariable C:\Temp\XmlConfig.dtsConfig Sample code, package and configuration file. ConfigurationApplication.cs ConfigurationSample.dtsx XmlConfig.dtsConfig

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  • Code Contracts: Hiding ContractException

    - by DigiMortal
    It’s time to move on and improve my randomizer I wrote for an example of static checking of code contracts. In this posting I will modify contracts and give some explanations about pre-conditions and post-conditions. Also I will show you how to avoid ContractExceptions and how to replace them with your own exceptions. As a first thing let’s take a look at my randomizer. public class Randomizer {     public static int GetRandomFromRange(int min, int max)     {         var rnd = new Random();         return rnd.Next(min, max);     }       public static int GetRandomFromRangeContracted(int min, int max)     {         Contract.Requires(min < max, "Min must be less than max");           var rnd = new Random();         return rnd.Next(min, max);     } } We have some problems here. We need contract for method output and we also need some better exception handling mechanism. As ContractException as type is hidden from us we have to switch from ContractException to some other Exception type that we can catch. Adding post-condition Pre-conditions are contracts for method’s input interface. Read it as follows: pre-conditions make sure that all conditions for method’s successful run are met. Post-conditions are contracts for output interface of method. So, post-conditions are for output arguments and return value. My code misses the post-condition that checks return value. Return value in this case must be greater or equal to minimum value and less or equal to maximum value. To make sure that method can run only the correct value I added call to Contract.Ensures() method. public static int GetRandomFromRangeContracted(int min, int max) {     Contract.Requires(min < max, "Min must be less than max");       Contract.Ensures(         Contract.Result<int>() >= min &&         Contract.Result<int>() <= max,         "Return value is out of range"     );       var rnd = new Random();     return rnd.Next(min, max); } I think that the line I added does not need any further comments. Avoiding ContractException for input interface ContractException lives in hidden namespace and we cannot see it at design time. But it is common exception type for all contract exceptions that we do not switch over to some other type. The case of Contract.Requires() method is simple: we can tell it what kind of exception we need if something goes wrong with contract it ensures. public static int GetRandomFromRangeContracted(int min, int max) {     Contract.Requires<ArgumentOutOfRangeException>(         min < max,         "Min must be less than max"     );       Contract.Ensures(         Contract.Result<int>() >= min &&         Contract.Result<int>() <= max,         "Return value is out of range"     );       var rnd = new Random();     return rnd.Next(min, max); } Now, if we violate the input interface contract giving min value that is not less than max value we get ArgumentOutOfRangeException. Avoiding ContractException for output interface Output interface is more complex to control. We cannot give exception type there and hope that this type of exception will be thrown if something goes wrong. Instead we have to use delegate that gathers information about problem and throws the exception we expect to be thrown. From documentation you can find the following example about the delegate I mentioned. Contract.ContractFailed += (sender, e) => {     e.SetHandled();     e.SetUnwind(); // cause code to abort after event     Assert.Fail(e.FailureKind.ToString() + ":" + e.DebugMessage); }; We can use this delegate to throw the Exception. Let’s move the code to separate method too. Here is our method that uses now ContractException hiding. public static int GetRandomFromRangeContracted(int min, int max) {     Contract.Requires(min < max, "Min must be less than max");       Contract.Ensures(         Contract.Result<int>() >= min &&         Contract.Result<int>() <= max,         "Return value is out of range"     );     Contract.ContractFailed += Contract_ContractFailed;       var rnd = new Random();     return rnd.Next(min, max)+1000; } And here is the delegate that creates exception. public static void Contract_ContractFailed(object sender,     ContractFailedEventArgs e) {     e.SetHandled();     e.SetUnwind();       throw new Exception(e.FailureKind.ToString() + ":" + e.Message); } Basically we can do in this delegate whatever we like to do with output interface errors. We can even introduce our own contract exception type. As you can see later then ContractFailed event is very useful at unit testing.

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  • Generate Strongly Typed Observable Events for the Reactive Extensions for .NET (Rx)

    - by Bobby Diaz
    I must have tried reading through the various explanations and introductions to the new Reactive Extensions for .NET before the concepts finally started sinking in.  The article that gave me the ah-ha moment was over on SilverlightShow.net and titled Using Reactive Extensions in Silverlight.  The author did a good job comparing the "normal" way of handling events vs. the new "reactive" methods. Admittedly, I still have more to learn about the Rx Framework, but I wanted to put together a sample project so I could start playing with the new Observable and IObservable<T> constructs.  I decided to throw together a whiteboard application in Silverlight based on the Drawing with Rx example on the aforementioned article.  At the very least, I figured I would learn a thing or two about a new technology, but my real goal is to create a fun application that I can share with the kids since they love drawing and coloring so much! Here is the code sample that I borrowed from the article: var mouseMoveEvent = Observable.FromEvent<MouseEventArgs>(this, "MouseMove"); var mouseLeftButtonDown = Observable.FromEvent<MouseButtonEventArgs>(this, "MouseLeftButtonDown"); var mouseLeftButtonUp = Observable.FromEvent<MouseButtonEventArgs>(this, "MouseLeftButtonUp");       var draggingEvents = from pos in mouseMoveEvent                              .SkipUntil(mouseLeftButtonDown)                              .TakeUntil(mouseLeftButtonUp)                              .Let(mm => mm.Zip(mm.Skip(1), (prev, cur) =>                                  new                                  {                                      X2 = cur.EventArgs.GetPosition(this).X,                                      X1 = prev.EventArgs.GetPosition(this).X,                                      Y2 = cur.EventArgs.GetPosition(this).Y,                                      Y1 = prev.EventArgs.GetPosition(this).Y                                  })).Repeat()                          select pos;       draggingEvents.Subscribe(p =>     {         Line line = new Line();         line.Stroke = new SolidColorBrush(Colors.Black);         line.StrokeEndLineCap = PenLineCap.Round;         line.StrokeLineJoin = PenLineJoin.Round;         line.StrokeThickness = 5;         line.X1 = p.X1;         line.Y1 = p.Y1;         line.X2 = p.X2;         line.Y2 = p.Y2;         this.LayoutRoot.Children.Add(line);     }); One thing that was nagging at the back of my mind was having to deal with the event names as strings, as well as the verbose syntax for the Observable.FromEvent<TEventArgs>() method.  I came up with a couple of static/helper classes to resolve both issues and also created a T4 template to auto-generate these helpers for any .NET type.  Take the following code from the above example: var mouseMoveEvent = Observable.FromEvent<MouseEventArgs>(this, "MouseMove"); var mouseLeftButtonDown = Observable.FromEvent<MouseButtonEventArgs>(this, "MouseLeftButtonDown"); var mouseLeftButtonUp = Observable.FromEvent<MouseButtonEventArgs>(this, "MouseLeftButtonUp"); Turns into this with the new static Events class: var mouseMoveEvent = Events.Mouse.Move.On(this); var mouseLeftButtonDown = Events.Mouse.LeftButtonDown.On(this); var mouseLeftButtonUp = Events.Mouse.LeftButtonUp.On(this); Or better yet, just remove the variable declarations altogether:     var draggingEvents = from pos in Events.Mouse.Move.On(this)                              .SkipUntil(Events.Mouse.LeftButtonDown.On(this))                              .TakeUntil(Events.Mouse.LeftButtonUp.On(this))                              .Let(mm => mm.Zip(mm.Skip(1), (prev, cur) =>                                  new                                  {                                      X2 = cur.EventArgs.GetPosition(this).X,                                      X1 = prev.EventArgs.GetPosition(this).X,                                      Y2 = cur.EventArgs.GetPosition(this).Y,                                      Y1 = prev.EventArgs.GetPosition(this).Y                                  })).Repeat()                          select pos; The Move, LeftButtonDown and LeftButtonUp members of the Events.Mouse class are readonly instances of the ObservableEvent<TTarget, TEventArgs> class that provide type-safe access to the events via the On() method.  Here is the code for the class: using System; using System.Collections.Generic; using System.Linq;   namespace System.Linq {     /// <summary>     /// Represents an event that can be managed via the <see cref="Observable"/> API.     /// </summary>     /// <typeparam name="TTarget">The type of the target.</typeparam>     /// <typeparam name="TEventArgs">The type of the event args.</typeparam>     public class ObservableEvent<TTarget, TEventArgs> where TEventArgs : EventArgs     {         /// <summary>         /// Initializes a new instance of the <see cref="ObservableEvent"/> class.         /// </summary>         /// <param name="eventName">Name of the event.</param>         protected ObservableEvent(String eventName)         {             EventName = eventName;         }           /// <summary>         /// Registers the specified event name.         /// </summary>         /// <param name="eventName">Name of the event.</param>         /// <returns></returns>         public static ObservableEvent<TTarget, TEventArgs> Register(String eventName)         {             return new ObservableEvent<TTarget, TEventArgs>(eventName);         }           /// <summary>         /// Creates an enumerable sequence of event values for the specified target.         /// </summary>         /// <param name="target">The target.</param>         /// <returns></returns>         public IObservable<IEvent<TEventArgs>> On(TTarget target)         {             return Observable.FromEvent<TEventArgs>(target, EventName);         }           /// <summary>         /// Gets or sets the name of the event.         /// </summary>         /// <value>The name of the event.</value>         public string EventName { get; private set; }     } } And this is how it's used:     /// <summary>     /// Categorizes <see cref="ObservableEvents"/> by class and/or functionality.     /// </summary>     public static partial class Events     {         /// <summary>         /// Implements a set of predefined <see cref="ObservableEvent"/>s         /// for the <see cref="System.Windows.System.Windows.UIElement"/> class         /// that represent mouse related events.         /// </summary>         public static partial class Mouse         {             /// <summary>Represents the MouseMove event.</summary>             public static readonly ObservableEvent<UIElement, MouseEventArgs> Move =                 ObservableEvent<UIElement, MouseEventArgs>.Register("MouseMove");               // additional members omitted...         }     } The source code contains a static Events class with prefedined members for various categories (Key, Mouse, etc.).  There is also an Events.tt template that you can customize to generate additional event categories for any .NET type.  All you should have to do is add the name of your class to the types collection near the top of the template:     types = new Dictionary<String, Type>()     {         //{ "Microsoft.Maps.MapControl.Map, Microsoft.Maps.MapControl", null }         { "System.Windows.FrameworkElement, System.Windows", null },         { "Whiteboard.MainPage, Whiteboard", null }     }; The template is also a bit rough at this point, but at least it generates code that *should* compile.  Please let me know if you run into any issues with it.  Some people have reported errors when trying to use T4 templates within a Silverlight project, but I was able to get it to work with a little black magic...  You can download the source code for this project or play around with the live demo.  Just be warned that it is at a very early stage so don't expect to find much today.  I plan on adding alot more options like pen colors and sizes, saving, printing, etc. as time permits.  HINT: hold down the ESC key to erase! Enjoy! Additional Resources Using Reactive Extensions in Silverlight DevLabs: Reactive Extensions for .NET (Rx) Rx Framework Part III - LINQ to Events - Generating GetEventName() Wrapper Methods using T4

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