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• C - Complicated pointer declarations - help understanding

  - by Emmel

  In my burgeoning new self-education in the C language, I've come across a set of declarations that I do not understand how to read. I'd love for someone to break these down. I'll explain at the bottom where I got these examples from. 1. char (*(*x())[])() "x: function returning pointer to array[] of pointer to function returning char" - huh? 2. char (*(*x[3])())[5] "x: array[3] of pointer to function returning pointer to array[5] of char" - come again? 3. char **argv This I understand. "Pointer to pointer to char." But what I don't understand is -- what's the use case for a pointer to a pointer? Follow-up question: does anyone every use declarations this complex or is this just academic fun on the part of the authors of the examples I got this from? These examples are from section 5.12 of the K&R book. This is the first time I'm genuinely stumped by an explanation, in an otherwise well-written classic. Thanks.

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• Why is an Add method required for { } initialization?

  - by Dan Tao

  To use initialization syntax like this: var contacts = new ContactList { { "Dan", "[email protected]" }, { "Eric", "[email protected]" } }; ...my understanding is that my ContactList type would need to define an Add method that takes two string parameters: public void Add(string name, string email); What's a bit confusing to me about this is that the { } initializer syntax seems most useful when creating read-only or fixed-size collections. After all it is meant to mimic the initialization syntax for an array, right? (OK, so arrays are not read-only; but they are fixed size.) And naturally it can only be used when the collection's contents are known (at least the number of elements) at compile-time. So it would almost seem that the main requirement for using this collection initializer syntax (having an Add method and therefore a mutable collection) is at odds with the typical case in which it would be most useful. I'm sure I haven't put as much thought into this matter as the C# design team; it just seems that there could have been different rules for this syntax that would have meshed better with its typical usage scenarios. Am I way off base here? Is the desire to use the { } syntax to initialize fixed-size collections not as common as I think? What other factors might have influenced the formulation of the requirements for this syntax that I'm simply not thinking of?

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• jQuery performance

  - by jAndy

  Hi Folks, imagine you have to do DOM manipulation like a lot (in my case, it's kind of a dynamic list). Look at this example: var $buffer = $('<ul/>', { 'class': '.custom-example', 'css': { 'position': 'absolute', 'top': '500px' } }); $.each(pages[pindex], function(i, v){ $buffer.append(v); }); $buffer.insertAfter($root); "pages" is an array which holds LI elements as jQuery object. "$root" is an UL element What happens after this code is, both UL's are animated (scrolling) and finally, within the callback of animate this code is executed: $root.detach(); $root = $buffer; $root.css('top', '0px'); $buffer = null; This works very well, the only thing I'm pi**ed off is the performance. I do cache all DOM elements I'm laying a hand on. Without looking too deep into jQuery's source code, is there a chance that my performance issues are located there? Does jQuery use DocumentFragments to append things? If you create a new DOM element with var new = $('<div/>') it is only stored in memory at this point isnt it?

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• Python Twitter library: which one?

  - by Parand

  I realize this is a bit of a lazyweb question, but I wanted to see which python library for Twitter people have had good experiences with. I've used Python Twitter Tools and like its brevity and beauty of interface, but it doesn't seem to be one of the popular ones - it's not even listed on the Twitter Libraries page. There are, however, plenty of others listed: oauth-python-twitter2 by Konpaku Kogasa. Combines python-twitter and oauth-python-twitter to create an evolved OAuth Pokemon. python-twitter by DeWitt Clinton. This library provides a pure Python interface for the Twitter API. python-twyt by Andrew Price. BSD licensed Twitter API interface library and command line client. twitty-twister by Dustin Sallings. A Twisted interface to Twitter. twython by Ryan McGrath. REST and Search library inspired by python-twitter. Tweepy by Josh Roesslein. Supports OAuth, Search API, Streaming API. My requirements are fairly simple: Be able to use OAuth Be able to follow a user Be able to send a direct message Be able to post Streaming API would be nice Twisted one aside (I'm not using twisted in this case), have you used any of the others, and if so, do you recommend them? [Update] FWIW, I ended up going with Python Twitter Tools again. The new version supported OAuth nicely, and it's a very clever API, so I stuck to it.

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• WPF TexBox TwoWay Binding Problem when ValidationRules used

  - by ignis

  I seem to have a problem with TwoWay DataBinding - my application has a window with a bunch of textboxes that allow to edit values of the properties they are bound to. Everything works well except for textboxes that also have a validation rule defined, in which case no text is displayed in the textbox when the window opens (binding back-to-source still works fine for those). If I remove Validation rule, everything's back to normal. I searched for an answer to this for a few hours now, but somehow did not even find anyone else complaining of the same issue. I am completely new to WPF, and I am sure it is just a silly mistake I have somewhere in my code... I will greatly appreciate any feedback... <TextBox Margin="40,2,20,0" Grid.Column="0" Grid.Row="1" Background="#99FFFFFF" > <Binding Path="LastName" Mode="TwoWay" ValidatesOnDataErrors="true" UpdateSourceTrigger="LostFocus" > <Binding.ValidationRules> <validation:StringNameValidationRule /> </Binding.ValidationRules> </Binding> </TextBox>

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• How to implement Master-Detail with Multi-Selection in WPF?

  - by gehho

  Hi, I plan to create a typical Master-Detail scenario, i.e. a collection of items displayed in a ListView via DataBinding to an ICollectionView, and details about the selected item in a separate group of controls (TextBoxes, NumUpDowns...). No problem so far, actually I have already implemented a pretty similar scenario in an older project. However, it should be possible to select multiple items in the ListView and get the appropriate shared values displayed in the detail view. This means, if all selected items have the same value for a property, this value should be displayed in the detail view. If they do not share the same value, the corresponding control should provide some visual clue for the user indicating this, and no value should be displayed (or an "undefined" state in a CheckBox for example). Now, if the user edits the value, this change should be applied to all selected items. Further requirements are: MVVM compatibility (i.e. not too much code-behind) Extendability (new properties/types can be added later on) Does anyone have experience with such a scenario? Actually, I think this should be a very common scenario. However, I could not find any details on that topic anywhere. Thanks! gehho. PS: In the older project mentioned above, I had a solution using a subclass of the ViewModel which handles the special case of multi-selection. It checked all selected items for equality and returned the appropriate values. However, this approach had some drawbacks and somehow seemed like a hack because (besides other smelly things) it was necessary to break the synchronization between the ListView and the detail view and handle it manually.

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• Can Sql Server 2005 Pivot table have nText passed into it?

  - by manemawanna

  Right bit of a simple question can I input nText into a pivot table? (SQL Server 2005) What I have is a table which records the answers to a questionnaire consisting of the following elements for example: UserID QuestionNumber Answer Mic 1 Yes Mic 2 No Mic 3 Yes Ste 1 Yes Ste 2 No Ste 3 Yes Bob 1 Yes Bob 2 No Bob 3 Yes With the answers being held in nText. Anyway what id like a Pivot table to do is: UserID 1 2 3 Mic Yes No Yes Ste Yes No Yes Bob Yes No Yes I have some test code, that creates a pivot table but at the moment it just shows the number of answers in each column (code can be found below). So I just want to know is it possible to add nText to a pivot table? As when I've tried it brings up errors and someone stated on another site that it wasn't possible, so I would like to check if this is the case or not. Just for further reference I don't have the opportunity to change the database as it's linked to other systems that I haven't created or have access too. Heres the SQL code I have at present below: DECLARE @query NVARCHAR(4000) DECLARE @count INT DECLARE @concatcolumns NVARCHAR(4000) SET @count = 1 SET @concatcolumns = '' WHILE (@count <=52) BEGIN IF @COUNT > 1 AND @COUNT <=52 SET @concatcolumns = (@concatcolumns + ' + ') SET @concatcolumns = (@concatcolumns + 'CAST ([' + CAST(@count AS NVARCHAR) + '] AS NVARCHAR)') SET @count = (@count+1) END DECLARE @columns NVARCHAR(4000) SET @count = 1 SET @columns = '' WHILE (@count <=52) BEGIN IF @COUNT > 1 AND @COUNT <=52 SET @columns = (@columns + ',') SET @columns = (@columns + '[' + CAST(@count AS NVARCHAR) + '] ') SET @count = (@count+1) END SET @query = ' SELECT UserID, ' + @concatcolumns + ' FROM( SELECT UserID, QuestionNumber AS qNum from QuestionnaireAnswers where QuestionnaireID = 7 ) AS t PIVOT ( COUNT (qNum) FOR qNum IN (' + @columns + ') ) AS PivotTable' select @query exec(@query)

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• "Public" nested classes or not

  - by Frederick

  Suppose I have a class 'Application'. In order to be initialised it takes certain settings in the constructor. Let's also assume that the number of settings is so many that it's compelling to place them in a class of their own. Compare the following two implementations of this scenario. Implementation 1: class Application { Application(ApplicationSettings settings) { //Do initialisation here } } class ApplicationSettings { //Settings related methods and properties here } Implementation 2: class Application { Application(Application.Settings settings) { //Do initialisation here } class Settings { //Settings related methods and properties here } } To me, the second approach is very much preferable. It is more readable because it strongly emphasises the relation between the two classes. When I write code to instantiate Application class anywhere, the second approach is going to look prettier. Now just imagine the Settings class itself in turn had some similarly "related" class and that class in turn did so too. Go only three such levels and the class naming gets out out of hand in the 'non-nested' case. If you nest, however, things still stay elegant. Despite the above, I've read people saying on StackOverflow that nested classes are justified only if they're not visible to the outside world; that is if they are used only for the internal implementation of the containing class. The commonly cited objection is bloating the size of containing class's source file, but partial classes is the perfect solution for that problem. My question is, why are we wary of the "publicly exposed" use of nested classes? Are there any other arguments against such use?

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• Sqlite3 "chained" query

  - by Arrieta

  I need to create a configuration file from a data file that looks as follows: MAN1_TIME '01-JAN-2010 00:00:00.0000 UTC' MAN1_RX 123.45 MAN1_RY 123.45 MAN1_RZ 123.45 MAN1_NEXT 'MAN2' MAN2_TIME '01-MAR-2010 00:00:00.0000 UTC' MAN2_RX 123.45 [...] MAN2_NEXT 'MANX' [...] MANX_TIME [...] This file describes different "legs" of a trajectory. In this case, MAN1 is chained to MAN2, and MAN2 to MANX. In the original file, the chains are not as obvious (i.e., they are non-sequential). I've managed to read the file and store in an Sqlite3 database (I'm using the Python interface). The table is stored with three columns: Id, Par, and Val; for instance, Id='MAN1', Par='RX', and Val='123.45'. I'm interested in querying such database for obtaining the information related to 'n' legs. In English, that would be: "Select RX,RY,RZ for the next five legs starting on MAN1" So the query would go to MAN1, retrieve RX, RY, RZ, then read the parameter NEXT and go to that Id, retrieve RX, RY, RZ; read the parameter NEXT; go to that one ... like this five times. How can I pass such query with "dynamic parameters"? Thank you.

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• Why is the Clojure Hello World program so slow compared to Java and Python?

  - by viksit

  Hi all, I'm reading "Programming Clojure" and I was comparing some languages I use for some simple code. I noticed that the clojure implementations were the slowest in each case. For instance, Python - hello.py def hello_world(name): print "Hello, %s" % name hello_world("world") and result, $ time python hello.py Hello, world real 0m0.027s user 0m0.013s sys 0m0.014s Java - hello.java import java.io.*; public class hello { public static void hello_world(String name) { System.out.println("Hello, " + name); } public static void main(String[] args) { hello_world("world"); } } and result, $ time java hello Hello, world real 0m0.324s user 0m0.296s sys 0m0.065s and finally, Clojure - hellofun.clj (defn hello-world [username] (println (format "Hello, %s" username))) (hello-world "world") and results, $ time clj hellofun.clj Hello, world real 0m1.418s user 0m1.649s sys 0m0.154s Thats a whole, garangutan 1.4 seconds! Does anyone have pointers on what the cause of this could be? Is Clojure really that slow, or are there JVM tricks et al that need to be used in order to speed up execution? More importantly - isn't this huge difference in performance going to be an issue at some point? (I mean, lets say I was using Clojure for a production system - the gain I get in using lisp seems completely offset by the performance issues I can see here). The machine used here is a 2007 Macbook Pro running Snow Leopard, a 2.16Ghz Intel C2D and 2G DDR2 SDRAM. BTW, the clj script I'm using is from here and looks like, #!/bin/bash JAVA=/System/Library/Frameworks/JavaVM.framework/Versions/1.6/Home/bin/java CLJ_DIR=/opt/jars CLOJURE=$CLJ_DIR/clojure.jar CONTRIB=$CLJ_DIR/clojure-contrib.jar JLINE=$CLJ_DIR/jline-0.9.94.jar CP=$PWD:$CLOJURE:$JLINE:$CONTRIB # Add extra jars as specified by `.clojure` file if [ -f .clojure ] then CP=$CP:`cat .clojure` fi if [ -z "$1" ]; then $JAVA -server -cp $CP \ jline.ConsoleRunner clojure.lang.Repl else scriptname=$1 $JAVA -server -cp $CP clojure.main $scriptname -- $* fi

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• Reference inherited class's <T>ype in a derived class

  - by DRapp

  I don't know if its possible or not, but here's what I need. I'm toying around with something and want to know if its possible since you can't create your own data type based on a sealed type such as int, Int32, Int64, etc. I want to create a top-level class that is defined of a given type with some common stuff. Then, derive this into two subclasses, but in this case, each class is based on either and int or Int64 type. From THAT instance, create an instance of either one and know its yped basis for parameter referenc / return settings. So when I need to create an instance of the "ThisClass", I don't have to know its type basis of either int or Int64, yet IT will know the type and be able to allow methods/functions to be called with the typed... This way, If I want to change my ThisClass definition from SubLevel1 to SubLevel2, I don't have to dance around all different data type definitions. Hope this makes sense.. public class TopLevel<T> { ... } pubic class SubLevel1 : TopLevel<int> { ... } public class SubLevel2 : TopLevel<Int64> { ... } public class ThisClass : SubLevel1 { ... public <based on the Int data type from SubLevel1> SomeFunc() { return <the Int value computed>; } }

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• SWT: problems with clicking button after using setEnabled() on Linux

  - by Laimoncijus

  Hi, I have a strange case with SWT and Button after using setEnabled() - seems if I disable and enable button at least once - I cannot properly click with mouse on it anymore... Already minify code to very basic: import org.eclipse.swt.SWT; import org.eclipse.swt.events.SelectionEvent; import org.eclipse.swt.events.SelectionListener; import org.eclipse.swt.layout.GridLayout; import org.eclipse.swt.widgets.Button; import org.eclipse.swt.widgets.Display; import org.eclipse.swt.widgets.Shell; public class TestButton { public TestButton() { Display display = new Display(); Shell shell = new Shell(display); GridLayout mainLayout = new GridLayout(); shell.setLayout(mainLayout); shell.setSize(100, 100); Button testButton = new Button(shell, SWT.PUSH); testButton.addSelectionListener(new TestClickListener()); testButton.setText("Click me!"); //testButton.setEnabled(false); //testButton.setEnabled(true); shell.open(); while (!shell.isDisposed()) { if (!display.readAndDispatch()) display.sleep(); } display.dispose(); } class TestClickListener implements SelectionListener { @Override public void widgetDefaultSelected(SelectionEvent e) { } @Override public void widgetSelected(SelectionEvent e) { System.out.println("Click!"); } } public static void main(String[] args) { new TestButton(); } } When I keep these 2 lines commented out - I can properly click on a button and always get "Click!" logged, but if I uncomment them - then I can't click on button properly with mouse anymore - button visually seems to be clicked, but nothing is logged... Am I doing something wrong here? Or maybe it's some kind of bug on Linux platform? Because on Mac running the same code I never experienced such problems... Thanks for any hint! P.S. Running code on Ubuntu 9.10, Gnome + Compiz, Sun Java 1.6.0.16

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• Re-using aggregate level formulas in SQL - any good tactics?

  - by Cade Roux

  Imagine this case, but with a lot more component buckets and a lot more intermediates and outputs. Many of the intermediates are calculated at the detail level, but a few things are calculated at the aggregate level: DECLARE @Profitability AS TABLE ( Cust INT NOT NULL ,Category VARCHAR(10) NOT NULL ,Income DECIMAL(10, 2) NOT NULL ,Expense DECIMAL(10, 2) NOT NULL ) ; INSERT INTO @Profitability VALUES ( 1, 'Software', 100, 50 ) ; INSERT INTO @Profitability VALUES ( 2, 'Software', 100, 20 ) ; INSERT INTO @Profitability VALUES ( 3, 'Software', 100, 60 ) ; INSERT INTO @Profitability VALUES ( 4, 'Software', 500, 400 ) ; INSERT INTO @Profitability VALUES ( 5, 'Hardware', 1000, 550 ) ; INSERT INTO @Profitability VALUES ( 6, 'Hardware', 1000, 250 ) ; INSERT INTO @Profitability VALUES ( 7, 'Hardware', 1000, 700 ) ; INSERT INTO @Profitability VALUES ( 8, 'Hardware', 5000, 4500 ) ; SELECT Cust ,Profit = SUM(Income - Expense) ,Margin = SUM(Income - Expense) / SUM(Income) FROM @Profitability GROUP BY Cust SELECT Category ,Profit = SUM(Income - Expense) ,Margin = SUM(Income - Expense) / SUM(Income) FROM @Profitability GROUP BY Category SELECT Profit = SUM(Income - Expense) ,Margin = SUM(Income - Expense) / SUM(Income) FROM @Profitability Notice how the same formulae have to be used at the different aggregation levels. This results in code duplication. I have thought of using UDFs (either scalar or table valued with an OUTER APPLY, since many of the final results may share intermediates which have to be calculated at the aggregate level), but in my experience the scalar and multi-statement table-valued UDFs perform very poorly. Also thought about using more dynamic SQL and applying the formulas by name, basically. Any other tricks, techniques or tactics to keeping these kinds of formulae which need to be applied at different levels in sync and/or organized?

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• TextBox should display text in hexadecimal in a specific format

  - by Owais Wani

  I have a textbox in my xaml file which is editable. Now according to my project requirements content in textbox should only be 0-9 and a-f (hexadecimal values) and textbox should take the input based on hexadecimal values. Demonstratation: 12 ab 32 a5 64 Now if my cursor is at the end and i go on pressing backspace, it shud remove the values as it happens in a general text box. Now If my cursor is at the beginning of a5, and i press "delete key", the value should become like: 12 ab 32 56 4 If my cursor is at the end of a5 and i press the 'delete key" nothing should happen. I had done this successful in my C++ application as follows: void CMSP430CommPanel::textEditorTextChanged (TextEditor& editor) { if(&editor == m_texti2cWrite) { int count = 0; int location; String text1 = m_texti2cWrite->getText(); String text = m_texti2cWrite->getText().removeCharacters(" "); String hexString = String::empty; int countCaret = m_texti2cWrite->getCaretPosition(); for(int i=0; i < text.length(); i++) { hexString = hexString + String (&text[i], 1); if((i+1) % 2 == 0) { if(i != text.length()-1) { hexString = hexString + T(" "); count ++; } } count ++; } m_texti2cWrite->setText(hexString,false); if(text1.length() == m_texti2cWrite->getCaretPosition()) { m_texti2cWrite->setCaretPosition(count); } else { m_texti2cWrite->setCaretPosition(countCaret); } } } where m_texti2cWrite is the name given to textbox. How can i implement the same case in my wpf application which is MVVM based. I have a textbox which shud take inputs as I said above. please help!!!

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• Extracting [] elements from form collection - mvc - should use icollection but have mix of types

  - by bergin

  hi there. have looked at Phil Haacks project on books at http://haacked.com/archive/2008/10/23/model-binding-to-a-list.aspx which has been useful, but I have a mix of data types. I use a modelview so that i can have a mix of objects, in this case: Order (ie order.id, order.date etc), Customer, SoilSamplingOrder and a list of SoilSamplingSubJobs which is like this [0].id, [0].field, [1].id, [1].field etc Perhaps I should be using ICollection instead of List? I had problems getting UpdateModel to work so I used an extract from collection method. the first 4 method calls : orderRepository.FindOrder(id); etc give the model the original to be edited. but after this point i'm a little lost in how to update the subjobs. I hope i have delineated enough to make sense of the problem. [HttpPost] public ActionResult Edit(int id, FormCollection collection) { Order order = orderRepository.FindOrder(id); Customer cust = orderRepository.FindCustomer(order.customer_id); IList<SoilSamplingSubJob> sssj = orderRepository.FindSubOrders(id); SoilSamplingOrder sso = orderRepository.FindSoilSampleOrder(id); try { UpdateModel(order, collection.ToValueProvider()); UpdateModel(cust, collection.ToValueProvider()); UpdateModel(sso, collection.ToValueProvider()); IList<SoilSamplingSubJob> sssjs = orderRepository.extractSSSJ(collection); foreach (var sj in sssjs) UpdateModel(sso, collection.ToValueProvider()); orderRepository.Save(); return RedirectToAction("Details", new { id=order.order_id}); } catch { return View(); } }

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• How to know if a graphics card provides hardware rendering for wpf

  - by happyclicker

  I have to run a wpf-app in an environment that has all the same dell-pc's with an intel gma 3000 graphics chip (onbard, Q963/Q965). The app renders only with software rendering (Stated so by the RenderCapability.Tier-property (it says the rendering tier is 0!) and I also see this with Perforator). On all of this machines, DirectX 9c is installed and DXDiag states on many but not on all of this machines, that Direct-3d and Direct-Draw-acceleration is activated. I checked also the registry if the setup of these machines disabled wpf-hw rendering but that's also not the case. On one machine I also updated the video-driver and dx with no success. I found a lot of ressources that say, that directX must be installed and active, so that wpf does not use its own software renderer but uses the DirectX HW-Rendering. But on the above machines, DX9c is installed but there is no hw rendering. May it be that wpf uses dx-graphicscards but does the communication with the graphics card direct and not over dx? How can I find out if a specific graphics-chip has to support hardware rendering for wpf or not. The statement that the graphics card must support dx 9c seems not to be the only condition. The second question is, if wpf renders through dx, is this done through direct-3d or is direct-draw used. Is there any good documentation on this topic?

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• Log4net Logging Problem : Very simple file appender logging not working

  - by contactmatt

  Here's my web.config information <configSections> <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/> </configSections> <log4net> <root> <level value="ALL" /> </root> <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender"> <file value="c:\temp\log-file.txt" /> <appendToFile value="true" /> <rollingStyle value="Size" /> <maxSizeRollBackups value="10" /> <maximumFileSize value="1MB" /> <staticLogFileName value="true" /> <layout type="log4net.Layout.SimpleLayout" /> </appender> </log4net> ... Here's the code that initalizes the logger protected void SendMessage() { log4net.Config.XmlConfigurator.Configure(); ILog log = LogManager.GetLogger(typeof(Contact)); ... log.Info("here we go!"); log.Debug("debug afasf"); ... } it doesn't work, no matter what I seem to do. I am referencing the 'log4net.dll' correctly, and by debugging the application i can see that the log object is getting initiated properly. This is a asp.net 3.5 framework web project. Any ideas/suggestions? I thought originally this error may be due to a file write permission constraint, but that doesn't seem to be the case (or so I think).

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• WPF ValidationRule Validate when the control is loaded

  - by PaN1C_Showt1Me

  Hi ! I have a control with this validation <MyPicker.SelectedItem> <Binding Path="Person.Value" Mode="TwoWay" UpdateSourceTrigger="PropertyChanged" NotifyOnValidationError="True"> <Binding.ValidationRules> <rules:MyValidationRule ValidationType="notnull"/> </Binding.ValidationRules> </Binding> </MyPicker.SelectedItem> This is the Validation Class: class MyValidationRule : ValidationRule { private string _validationType; public string ValidationType { get { return _validationType; } set { _validationType = value; } } public override ValidationResult Validate(object value, CultureInfo cultureInfo) { ValidationResult trueResult = new ValidationResult(true, null); switch (_validationType.ToLower()) { case "notnull": return value == null ? new ValidationResult(false, "EMPTY FIELD") : trueResult; default: return trueResult; } } } Question: When the property is changed, then the Validate( ) method is called which is correct. But to call this method at the very beginning when the MyControl is created? I need to prove immediate after initialize if the there's a null value in the control (and display a validation error)

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• Method binding to base method in external library can't handle new virtual methods "between"

  - by Berg

  Lets say I have a library, version 1.0.0, with the following contents: public class Class1 { public virtual void Test() { Console.WriteLine( "Library:Class1 - Test" ); Console.WriteLine( "" ); } } public class Class2 : Class1 { } and I reference this library in a console application with the following contents: class Program { static void Main( string[] args ) { var c3 = new Class3(); c3.Test(); Console.ReadKey(); } } public class Class3 : ClassLibrary1.Class2 { public override void Test() { Console.WriteLine("Console:Class3 - Test"); base.Test(); } } Running the program will output the following: Console:Class3 - Test Library:Class1 - Test If I build a new version of the library, version 2.0.0, looking like this: public class Class1 { public virtual void Test() { Console.WriteLine( "Library:Class1 - Test V2" ); Console.WriteLine( "" ); } } public class Class2 : Class1 { public override void Test() { Console.WriteLine("Library:Class2 - Test V2"); base.Test(); } } and copy this version to the bin folder containing my console program and run it, the results are: Console:Class3 - Test Library:Class1 - Test V2 I.e, the Class2.Test method is never executed, the base.Test call in Class3.Test seems to be bound to Class1.Test since Class2.Test didn't exist when the console program was compiled. This was very surprising to me and could be a big problem in situations where you deploy new versions of a library without recompiling applications. Does anyone else have experience with this? Are there any good solutions? This makes it tempting to add empty overrides that just calls base in case I need to add some code at that level in the future...

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• DIY intellisense on XPath - design approach? (WinForms app)

  - by Cheeso

  I read the DIY Intellisense article on code project, which was referenced from the Mimic Intellisense? question here on SO. I wanna do something similar, DIY intellisense, but for XPath not C#. The design approach used there makes sense to me: maintain a tree of terms, and when the "completion character" is pressed, in the case of C#, a dot, pop up the list of possible completions in a textfield. Then allow the user to select a term from the textfield either through typing, arrow keys, or double-click. How would you apply this to XPath autocompletion? should there be an autocomplete key? In XPath there is no obvious separator key like "dot" in C#. should the popup be triggered explicitly in some other way, let's say ctrl-. ? or should the parser try to autocomplete continuously? If I do the autocomplete continuously, how to scale it properly? There are 93 xpath functions, not counting overloads. I certainly don't want to popup a list of 93 choices. How do I decide when I've narrowed it enough to offer a useful lsit of possible completions? How to populate the tree of possible completions? For C#, it's easy: walk the type space via reflection. At a first level, the "syntax tree" for C# seems like a single tree, and the list of completions at any point depends on the graph of nodes you've traversed to that point. Typing System.Console. traverses to a certain node in that tree, and the list of completions is the set of child nodes available at that node in the tree. On the other hand, the xpath syntax seems like it is a "flatter" tree - function names, axis names, literals. Does this make sense? what have I not considered?

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• How do I pass a const reference in C#?

  - by Maciek

  In C++, passing const references is a common practice - for instance : #include <iostream> using namespace std; class X { public : X() {m_x = 0; } X(const int & x) {m_x = x; } X(const X & other) { *this = other; } X & operator = (const X & other) { m_x = other.m_x; return *this; } void print() { cout << m_x << endl; } private : int m_x; }; void main() { X x1(5); X x2(4); X x3(x2); x2 = x1; x1.print(); x2.print(); x3.print(); } This very simple example illustrates how it's done - pretty much. However I've noticed that in C# this doesn't seem to be the case. Do I have to pass const references in C# ? what do I need the "ref" keyword for? Please note that I know and understand what C# reference and value types are.

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• Excel COM Add-In dialog interrupts script

  - by usac

  Hi all! I have written an Excel COM Add-In in C++ for automation of Excel with VBA. It contains an own dialog showing some general informations about the Add-In. Now i create a button in Excel that opens the dialog. Leaving the dialog with the escape key leads to an Excel message that the script is being interrupted instead of just closing the dialog. I could suppress the interruption message with: Application.EnableCancelKey = xlDisabled But that seems not to be the solution as the script can not be interrupted any more. Here is an example how i use VBA to open the dialog: Private Sub ShowAboutDialog_Click() Dim oComAddIn As COMAddIn Set oComAddIn = Application.COMAddIns.Item("MyComAddIn.Example") oComAddIn.Connect = True Call oComAddIn.Object.ShowAboutDlg End Sub My guess is that the problem is somewhere in the message handler of the dialog: INT_PTR CALLBACK CAboutDialog::AboutDlg( HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam) { switch(uMsg) { ... case WM_COMMAND: if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL) { // Here, the ESCAPE key should also be trapped? EndDialog(hwndDlg, LOWORD(wParam)); return TRUE; } ... } return FALSE; } The Dialog is created with: DialogBox(g_hModule, MAKEINTRESOURCE(IDD_ABOUT), hWndParent, (DLGPROC)AboutDlg) Thanks a lot!

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• How do I display grouped XML data in a Flex pie chart?

  - by mclaughlinj

  I've looked into grouping XML data with GroupingCollections and AdvancedDataGrids, but I can't figure out how to display that data in a chart. Basically, what I want to do is group the data by the category field, which should give me two rows under red, one under blue, and one under green. When inputting this data into the pie chart, it should take up the right amount of space (1/2 for red, 1/4 each for blue and green). I don't need the other_data field, as I'd like to use the group name (category in this case) as the callout. Any suggestions? Sample data: <row> <category>red</category> <other_data>this shouldn't really matter</other_data> </row> <row> <category>blue</category> <other_data>this shouldn't really matter</other_data> </row> <row> <category>red</category> <other_data>this shouldn't really matter</other_data> </row> <row> <category>green</category> <other_data>this shouldn't really matter</other_data> </row>

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• Sorting, Filtering and Paging in ASP.NET MVC

  - by ali62b

  What is the best approach to implement these features and which part of project would involved? I see some example of JavaScript grids, but I'm talking about a general approach which best fits the MVC architecture. I've considered configuring routes and models to implement these features but I don't have a clear idea that if this is the right approach to implementing such features. On the one hand, I think if we put logic in routes (item/page/sort/), we would have benefits like bookmarking and avoiding JavaScript. On the other hand if we use JavaScript grids, we can have behavior like the old school grid views in ASP.NET web forms. I find that using HTML helpers may be useful for paging, but have no idea if they are good for sorting or not. I've looked at jQuery, tableSorter and quick search plug-ins, but they work just on the currently-fetched data and won't help in real sorting and filtering that may need to touch the database. I have some thoughts on using these tools side by side with AJAX to get something which works, but I have no idea if there are similar efforts done yet anywhere. Another approach I looked at was using Dynamic Data on web forms, but I didn't find any suggestions out there as to whether or not it is a good idea to integrate MVC and DD. I know implementing filtering and sorting for an individual case is simple (although it has some issues like using Dynamic LINQ, which is not yet a standard approach), but creating a sorting or filtering tool which works in all cases is the idea I'm looking for. (Maybe this is because I want have something in hand when web form developers are wondering why I'm writing same code each time I want to implement a sort scenario for different Entities).

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• c# webbrowser | pushed realtime quotes

  - by Eric

  Hi, I am programmer and share trader. Before I have written a day trading application. Until last week it was possible to fetch realtime quotes from http://aktien.boerse.de/aktien_startseite.php?view=2&order=name%20asc&liste=prime&page=0 . Every time the site was surfed the quotes had changed. The HTML contents could then be decoded with regular expressions (regex). Problem They have stopped this service by today. Now the quotes are not realtime when surfing on the page. The only way to get stock quotes now is to use pushed quotes "Push starten"-Button. However I do not know how to basically fetch them in C#. When I create a webbrowser element the only way which I know to get the push quotes out of it is to give the webbrowser element the focus send key ctrl+A and ctrl+C and insert the data some where for decoding. This is not desired since the control is moved away from the user and in case some other control is clicked during the process this may result in unexpected behaviour. Question So is there a proper way to decode push stock quotes in C#? Thanks a lot in advance, --eric

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