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  • Pls help working with Dropdownlist in scroll window.

    - by Rahul
    Hi all, Data is stored in the database table with the field document type and document id. And displayed in the scrollwindow, scrollwindow is editable. Data displayed like this: In scrollwindow dropdown items are quote, order, invoice etc. And suppose for Quote type document id is QTE100, and for order is ORD100 etc. In this format data is displayed in the scrollwindow. Here my query is at run time when user change the document type say for Quote to Order warning message should display like “This range is not valid”. And since the scrollwindow editable when user select any new document type from dropdown list system should allow to add that new document type and should not display any message. Pls somebody help me how can I achieve this???pls………pls…......pls For this I have written this code in dropdown document change event. Document Type Site_Scroll Document Type_CHG: warning "The range entered isn't valid."; clear window 'Document Type Site_Scroll'; fill window 'Document Type Site_Scroll' table sop_site_line_temp; But whenever I am changing any document from existing one getting the warning message like “This range is not valid” this is expected, but after changing when the window is filled again by temp table focus is setting to document type dropdown list. One more thing whenever I am going to select any new document type from document type I am getting the same warning message which is not expected, system should allow user to select new document type without giving any warning message. Pls….somebody give me some idea or pls modify my code….

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  • How am I able to create A List<T> containing a generic Interface?

    - by Conrad Clark
    I have a List which must contain IInteract Objects. But IInteract is a generic interface which requires 2 type arguments. My main idea is iterate through a list of Objects and "Interact" one with another if they didn't interact yet. So i have this object List<IObject> WorldObjects = new List<IObject>(); and this one: private List<IInteract> = new List<IInteract>(); Except I can't compile the last line because IInteract requires 2 type arguments. But I don't know what the arguments are until I add them. I could add interactions between Objects of Type A and A... or Objects of Type B and C. I want to create "Interaction" classes which do something with the "acting" object and the "target" object, but I want them to be independent from the objects... so I could add an Interaction between for instance... "SuperUltraClass" and... an "integer". Am I using the wrong approach?

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  • Test MVC using moq

    - by Raminder
    I am new to moq and I was trying to test a controller (MVC) behaviour that when the view raises a certain event, controller calls a certain function on model, here are the classes - public class Model { public void CalculateAverage() { ... } ... } public class View { public event EventHandler CalculateAverage; private void RaiseCalculateAverage() { if (CalculateAverage != null) { CalculateAverage(this, EventArgs.Empty); } } ... } public class Controller { private Model model; private View view; public Controller(Model model, View view) { this.model = model this.view = view; view.CalculaeAverage += view_CalculateAverage; } priavate void view_CalculateAverage(object sender, EventArgs args) { model.CalculateAverage(); } } and the test - [Test] public void ModelCalculateAverageCalled() { Mock<Model> modelMock = new Mock<Model>(); Mock<View> viewMock = new Mock<View>(); Controller controller = new Controller(modelMock.Object, viewMock.Object); viewMock.Raise(x => x.CalculateAverage += null, new EventArgs.Empty); modelMock.Verify(x => x.CalculateAverage()); //never comes here, test fails in above line and exits Assert.True(true); } The issue is that the test is failing in the second last line with "Invocation was not performed on the mock: x = x.CalculateAverage()". Another thing I noticed is that the test terminates on this second last line and the last line is never executed. Am I doing everything correct?

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  • Web service performing asynchronous call

    - by kornelijepetak
    I have a webservice method FetchNumber() that fetches a number from a database and then returns it to the caller. But just before it returns the number to the caller, it needs to send this number to another service so instantiates and runs the BackgroundWorker whose job is to send this number to another service. public class FetchingNumberService : System.Web.Services.WebService { [WebMethod] public int FetchNumber() { int value = Database.GetNumber(); AsyncUpdateNumber async = new AsyncUpdateNumber(value); return value; } } public class AsyncUpdateNumber { public AsyncUpdateNumber(int number) { sendingNumber = number; worker = new BackgroundWorker(); worker.DoWork += asynchronousCall; worker.RunWorkerAsync(); } private void asynchronousCall(object sender, DoWorkEventArgs e) { // Sending a number to a service (which is Synchronous) here } private int sendingNumber; private BackgroundWorker worker; } I don't want to block the web service (FetchNumber()) while sending this number to another service, because it can take a long time and the caller does not care about sending the number to another service. Caller expects this to return as soon as possible. FetchNumber() makes the background worker and runs it, then finishes (while worker is running in the background thread). I don't need any progress report or return value from the background worker. It's more of a fire-and-forget concept. My question is this. Since the web service object is instantiated per method call, what happens when the called method (FetchNumber() in this case) is finished, while the background worker it instatiated and ran is still running? What happens to the background thread? When does GC collect the service object? Does this prevent the background thread from executing correctly to the end? Are there any other side-effects on the background thread? Thanks for any input.

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  • placing pop up based on the mouse position(x,y)RSS Feed

    - by prince23
    hi, right now i am showing pop at the botton of the screen. i need to change them according to the value(x,y) whhere i have moved the mouse here i need to get the MouseEventArgs e postion that is its x:value and y:value based on that i need to place the pop up in the screen i need to get the mouse x, y postion? is it possiable to get its value? private void DG_LoadingRow(object sender, DataGridRowEventArgs e) { DataGridRow row = e.Row; int index = 0; foreach (DataGridColumn colGrid in DG.Columns) { if(colGrid .Header == "ID" || colGrid .Header == "Name") { FrameworkElement cellContent = colGrid .GetCellContent(e.Row); DataGridCell cell = cellContent.Parent as DataGridCell; cell.MouseEnter -= cell_MouseEnter; cell.MouseEnter += new MouseEventHandler(cell_MouseEnter); cell.MouseLeave -= cell_MouseLeave; cell.MouseLeave += new MouseEventHandler(cell_MouseLeave); } } } void cell_MouseLeave(object sender, MouseEventArgs e) { //Hide your popup } void cell_MouseEnter(object sender, MouseEventArgs e) { **// here i need to get the mouse position that is its x,y value based on that i can place my modal pop up in that postion. my pop is defined in xaml page here i will be assigning only its position where i need to place my modal pop up.** //

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  • InvalidCastException when getting Text from a Label referenced by dynamicaly built String, Fix?

    - by Chris
    NET Version: 3.5 Ok, I recieve an error (System.InvalidCastException was unhandled. Message="Unable to cast object of type 'System.Windows.Forms.Control[]' to type 'System.Windows.Forms.Label'.") when trying to get Text from a Label referenced by a dynamicly built string. Here's my situation; I have an array of 250 labels named l1 - l250. What I want to do is loop through them using this while statement: int c = 1; while (c < 251) { string k = "l" + c.ToString(); //dynamic name of Control(Label) object ka = Controls.Find(k, true); string ct = ((Label)ka).Text; //<<Error Occurs Here build = build + ct; c++; } and get the text value of each to build a string named build. I don't get any build errors, just this while debuging. While debuging I can go down to view my local variables. When looking through these, I can view the contents of object ka; it does contain the correct Text value of the correct Label I want to "access". I just don't understand how to get there. The text value is listed under "[0]" which is the only subcatagory for "ka".

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  • Function with parameter type that has a copy-constructor with non-const ref chosen?

    - by Johannes Schaub - litb
    Some time ago I was confused by the following behavior of some code when I wanted to write a is_callable<F, Args...> trait. Overload resolution won't call functions accepting arguments by non-const ref, right? Why doesn't it reject in the following because the constructor wants a Test&? I expected it to take f(int)! struct Test { Test() { } // I want Test not be copyable from rvalues! Test(Test&) { } // But it's convertible to int operator int() { return 0; } }; void f(int) { } void f(Test) { } struct WorksFine { }; struct Slurper { Slurper(WorksFine&) { } }; struct Eater { Eater(WorksFine) { } }; void g(Slurper) { } void g(Eater) { } // chooses this, as expected int main() { // Error, why? f(Test()); // But this works, why? g(WorksFine()); } Error message is m.cpp: In function 'int main()': m.cpp:33:11: error: no matching function for call to 'Test::Test(Test)' m.cpp:5:3: note: candidates are: Test::Test(Test&) m.cpp:2:3: note: Test::Test() m.cpp:33:11: error: initializing argument 1 of 'void f(Test)' Can you please explain why one works but the other doesn't?

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  • Searching with a UISearchbar is slow and blocking the main thread.

    - by Robert
    I have a Table with over 3000 entries and searching is very slow. At the moment I am doing just like in the 'TableSearch' example code (but without scopes) - (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString { [self filterContentForSearchText: searchString]; // Return YES to cause the search result table view to be reloaded. return YES; } And the filterContentForSearchText method is as follows: - (void) filterContentForSearchText:(NSString*)searchText { // Update the filtered array based on the search text // First clear the filtered array. [filteredListContent removeAllObjects]; // Search the main list whose name matches searchText // add items that match to the filtered array. if (fetchedResultsController.fetchedObjects) { for (id object in fetchedResultsController.fetchedObjects) { NSString* searchTarget = [tableTypeDelegate getStringForSearchFilteringFromObject:object]; if ([searchTarget rangeOfString:searchText options:(NSCaseInsensitiveSearch|NSDiacriticInsensitiveSearch)].location != NSNotFound) { [filteredListContent addObject:object]; } } } } My question is twofold: How do can I make the searching process faster? How can I stop the search from blocking the main thread? i.e. stop it preventing the user from typing more characters. For the second part, I tried "performSelector:withObject:afterDelay:" and "cancelPreviousPerformRequests..." without much success. I suspect that I will need to use threading instead, but I do not have much experience with it.

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  • Rails rake test returns an error message

    - by eakkas
    I am a rails newbie and receive the following message when I run rake test. This is a an application based on rails community engine. I tried creating a test application just to make sure that my gems etc. are fine and I am able to run rake test successfully in that application. It would be great if someone could shed a light on what is going wrong... /usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/whiny_nil.rb:52:in `method_missing': undefined method `merge' for nil:NilClass (NoMethodError) from /home/eakkas/NetBeansProjects/hello_ce/vendor/plugins/community_engine/app/controllers/users_controller.rb:17 from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `require' from /usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:158:in `require_without_desert' from /usr/lib/ruby/gems/1.8/gems/desert-0.5.3/lib/desert/ruby/object.rb:8:in `require' from /usr/lib/ruby/gems/1.8/gems/desert-0.5.3/lib/desert/ruby/object.rb:32:in `__each_matching_file' from /usr/lib/ruby/gems/1.8/gems/desert-0.5.3/lib/desert/ruby/object.rb:7:in `require' from /usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:265:in `require_or_load' from /usr/lib/ruby/gems/1.8/gems/desert-0.5.3/lib/desert/rails/dependencies.rb:27:in `depend_on' from /usr/lib/ruby/gems/1.8/gems/desert-0.5.3/lib/desert/rails/dependencies.rb:26:in `each' from /usr/lib/ruby/gems/1.8/gems/desert-0.5.3/lib/desert/rails/dependencies.rb:26:in `depend_on' from /usr/lib/ruby/gems/1.8/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:136:in `require_dependency' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:414:in `load_application_classes' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:413:in `each' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:413:in `load_application_classes' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:411:in `each' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:411:in `load_application_classes' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:197:in `process' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `send' from /usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `run'

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  • Null reference exceptions in .net

    - by Carlo
    Hello, we're having this big problem with our application. It's a rather large application with several modules, and thousands and thousands lines of code. A lot of parts of the application are designed to exist only with a reference to another object, for example a Person object can never exists without a House object, so if you at any point in the app say: bool check = App.Person.House == null; check should always be false (by design), so, to keep using that example, while creating modules, testing, debugging, App.Person.House is never null, but once we shipped the application to our client, they started getting a bunch of NullReferenceException with the objects that by design, should never have a null reference. They tell us the bug, we try to reproduce it here, but 90% of the times we can't, because here it works fine. The app is being developed with C# and WPF, and by design, it only runs on Windows XP SP 3, and the .net framework v3.5, so we KNOW the user has the same operative system, service pack, and .net framework version as we do here, but they still get this weird NullReferenceExceptions that we can't reproduce. So, I'm just wondering if anyone has seen this before and how you fixed it, we have the app running here at least 8 hours a day in 5 different computers, and we never see those exceptions, this only happens to the client for some reason. ANY thought, any clue, any solution that could get us closer to fixing this problem will be greatly appreciated. Thanks!

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  • Set .aspx page title to that of an Eval

    - by user1860529
    I am trying to use an <%# Eval("name") %> to be the title of my page. I can't seem to figure out any solutions online. I have tried the other StackOverflow question but that did now work either. The page is a bio.aspx and on the site it is displayed as bio.aspx?id=123 so the page title needs to vary depending on the ID. I figured I could just use the Eval("name") but no luck yet. I currently am using JavaScript: window.onload = function() { document.title = '<%# Eval("name") %> | Title Line'; } This works, but it still leaves the title tags empty, and it's kind of spammy. Here is the codebehind: using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; public partial class DoctorBio : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Page.Title = "Your Page Title"; HtmlMeta metaDescription = new HtmlMeta(); metaDescription.Name = "description"; metaDescription.Content = "brief description"; Page.Header.Controls.Add(metaDescription); HtmlMeta metaKeywords = new HtmlMeta(); metaKeywords.Name = "keywords"; metaKeywords.Content = "keywords, keywords"; Page.Header.Controls.Add(metaKeywords); } protected void SetPageTitle(object title) { this.Title = title.ToString(); } protected string ReplaceLineBreaks(object text) { string newText = text as string; if (newText == null) { return string.Empty; } return newText.Replace("\r\n", "<br />"); } }

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  • Rails Tableless Model

    - by mplacona
    I'm creating a tableless Rails model, and am a bit stuck on how I should use it. Basically I'm trying to create a little application using Feedzirra that scans a RSS feed every X seconds, and then sends me an email with only the updates. I'm actually trying to use it as an activerecord model, and although I can get it to work, it doesn't seem to "hold" data as expected. As an example, I have an initializer method that parses the feed for the first time. On the next requests, I would like to simply call the get_updates method, which according to feedzirra, is the existing object (created during the initialize) that gets updated with only the differences. I'm finding it really hard to understand how this all works, as the object created on the initialize method doesn't seem to persist across all the methods on the model. My code looks something like: def initialize feed parse here end def get_updates feedzirra update passing the feed object here end Not sure if this is the right way of doing it, but it all seems a bit confusing and not very clear. I could be over or under-doing here, but I'd like your opinion about this approach. Thanks in advance

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  • Read specific line from text file, according to Checked Listbox selection number.

    - by Manolis
    Heya, i want to create an application which will read a specific line from a text file and show it in a textbox. The line will be chosen according to the number of the listbox selection i will make. Here's the code: Public Class Form1 Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load End Sub Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Dim i As Integer For i = 0 To Me.CheckedListBox1.CheckedIndices.Count - 1 Me.CheckedListBox1.SetItemChecked(Me.CheckedListBox1.CheckedIndices(0),False) Next i End Sub Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click If CheckedListBox1.CheckedItems.Count <> 0 Then Dim reader As New System.IO.StreamReader(CurDir() & "\" & "READ.txt") Dim x As Integer Dim s As String = "" For x = 0 To CheckedListBox1.CheckedItems.Count - 1 s = s & "Answer " & (x + 1).ToString & ") " & CheckedListBox1.CheckedItems(x).ToString & ControlChars.CrLf & reader.ReadLine() & ControlChars.CrLf & ControlChars.CrLf Next x Answer.Text = (s) Else MessageBox.Show("Please select questions.", "Error", _ MessageBoxButtons.OK, _ MessageBoxIcon.Information) Return End If End Sub End Class So lets say i 'check' the first, second, and fifth items from the checked listbox, i want it to read from the text file the first, second, and fifth lines of text and show them in the textbox. The current code just reads line 1, 2, 3 (...) in order, no matter what item i have 'checked'. Thanks in advance!

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  • @attribute elements in XML

    - by danit
    Here is my XML: ["link"]=> array(2) { [0]=> object(SimpleXMLElement)#244 (1) { ["@attributes"]=> array(3) { ["type"]=> string(9) "text/html" ["href"]=> string(48) "http://twitter.com/MoodleDan/statuses/1226112723" ["rel"]=> string(9) "alternate" } } [1]=> object(SimpleXMLElement)#245 (1) { ["@attributes"]=> array(3) { ["type"]=> string(9) "image/png" ["href"]=> string(59) "http://a3.twimg.com/profile_images/226895523/Dan_normal.png" ["rel"]=> string(5) "image" } } } ["author"]=> object(SimpleXMLElement)#246 (2) { ["name"]=> string(14) "Dan Humpherson" ["uri"]=> string(16) "http://vl3.co.uk" } The above XML is part of a larger array, but how do i get the href -> ["href"]=> string(59) "http://a3.twimg.com/profile_images/226895523/Dan_normal.png" Element to echo in PHP? This is what I tried (Wrong I know) foreach ($entry->link as $img) { echo $img->href; echo "<img src='". $img ."' />"; }

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  • Constructor and Destructors in C++ [Not a question] [closed]

    - by Jack
    I am using gcc. Please tell me if I am wrong - Lets say I have two classes A & B class A { public: A(){cout<<"A constructor"<<endl;} ~A(){cout<<"A destructor"<<endl;} }; class B:public A { public: B(){cout<<"B constructor"<<endl;} ~B(){cout<<"B destructor"<<endl;} }; 1) The first line in B's constructor should be a call to A's constructor ( I assume compiler automatically inserts it). Also the last line in B's destructor will be a call to A's destructor (compiler does it again). Why was it built this way? 2) When I say A * a = new B(); compiler creates a new B object and checks to see if A is a base class of B and if it is it allows 'a' to point to the newly created object. I guess that is why we don't need any virtual constructors. ( with help from @Tyler McHenry , @Konrad Rudolph) 3) When I write delete a compiler sees that a is an object of type A so it calls A's destructor leading to a problem which is solved by making A's destructor virtual. As user - Little Bobby Tables pointed out to me all destructors have the same name destroy() in memory so we can implement virtual destructors and now the call is made to B's destructor and all is well in C++ land. Please comment.

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  • Strange behaviour with PHP/Pear HTML_Quickform and Firfox 3.6

    - by chessweb
    I am using PHP/Pear HTMLQuickForm and HTMLQuickForm_Controller to do some stuff with HTML-forms. Then I noticed that certain phone numbers would not be displayed even though the data had been loaded correctly. I boiled it down to the following rather strange phenomenons that have me completely baffled: $this->addElement('static', null, 'Telefon:', '04556-8978765'); will just show "Telefon:" in Firefox 3.6. In IE8 I see "Telefon: 04556-8978765" as expected. $this->addElement('static', null, 'Telefon:', '904556-8978765'); displays just "Telefon: 9" in Firefox 3.6 and correctly "Telefon: 904556-8978765" in IE8. On the other hand $this->addElement('static', null, 'Telefon:', '099828-67776554'); shows "Telefon: 099828-67776554" in both browsers. So my question is this: What is so special about the string 04556-8978765 that Firefox 3.6 refuses to render it? And it gets even weirder: The string 0208-23345 and 02232-12345 have the same problem, but when I prefix them with any other character, then unlike 04556-8978765 they are displayed alright. And it is not as if the missing strings are not rendered at all. On page reload I see them for a short time and then they disappear for good. Now try to guess the result of $this->addElement('static', null, 'Telefon:', '04556-8978765'); $this->addElement('static', null, 'Telefon:', '04556-8978765'); Right, it is not Telefon: 04556-8978765 Telefon: 04556-8978765 as expected, but rather Telefon: Telefon: 04556-8978765 Can anybody make any sense of this?

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  • Getting around IBActions limited scope

    - by Septih
    Hello, I have an NSCollectionView and the view is an NSBox with a label and an NSButton. I want a double click or a click of the NSButton to tell the controller to perform an action with the represented object of the NSCollectionViewItem. The Item View is has been subclassed, the code is as follows: #import <Cocoa/Cocoa.h> #import "WizardItem.h" @interface WizardItemView : NSBox { id delegate; IBOutlet NSCollectionViewItem * viewItem; WizardItem * wizardItem; } @property(readwrite,retain) WizardItem * wizardItem; @property(readwrite,retain) id delegate; -(IBAction)start:(id)sender; @end #import "WizardItemView.h" @implementation WizardItemView @synthesize wizardItem, delegate; -(void)awakeFromNib { [self bind:@"wizardItem" toObject:viewItem withKeyPath:@"representedObject" options:nil]; } -(void)mouseDown:(NSEvent *)event { [super mouseDown:event]; if([event clickCount] > 1) { [delegate performAction:[wizardItem action]]; } } -(IBAction)start:(id)sender { [delegate performAction:[wizardItem action]]; } @end The problem I've run into is that as an IBAction, the only things in the scope of -start are the things that have been bound in IB, so delegate and viewItem. This means that I cannot get at the represented object to send it to the delegate. Is there a way around this limited scope or a better way or getting hold of the represented object? Thanks.

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  • __toString magic and type coercion

    - by TomcatExodus
    I've created a Template class for managing views and their associated data. It implements Iterator and ArrayAccess, and permits "sub-templates" for easy usage like so: <p><?php echo $template['foo']; ?></p> <?php foreach($template->post as $post): ?> <p><?php echo $post['bar']; ?></p> <?php endforeach; ?> Anyways, rather than using inline core functions, such as hash() or date(), I figured it would be useful to create a class called TemplateData, which would act as a wrapper for any data stored in the templates. This way, I can add a list of common methods for formatting, for example: echo $template['foo']->asCase('upper'); echo $template['bar']->asDate('H:i:s'); //etc.. When a value is set via $template['foo'] = 'bar'; in the controllers, the value of 'bar' is stored in it's own TemplateData object. I've used the magic __toString() so when you echo a TemplateData object, it casts to (string) and dumps it's value. However, despite the mantra controllers and views should not modify data, whenever I do something like this: $template['foo'] = 1; echo $template['foo'] + 1; //exception It dies on a Object of class TemplateData could not be converted to int; Unless I recast $template['foo'] to a string: echo ((string) $template['foo']) + 1; //outputs 2 Sort of defeats the purpose having to jump through that hoop. Are there any workarounds for this sort of behavior that exist, or should I just take this as it is, an incidental prevention of data modification in views?

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  • Implementing list position locator in C++?

    - by jfrazier
    I am writing a basic Graph API in C++ (I know libraries already exist, but I am doing it for the practice/experience). The structure is basically that of an adjacency list representation. So there are Vertex objects and Edge objects, and the Graph class contains: list<Vertex *> vertexList list<Edge *> edgeList Each Edge object has two Vertex* members representing its endpoints, and each Vertex object has a list of Edge* members representing the edges incident to the Vertex. All this is quite standard, but here is my problem. I want to be able to implement deletion of Edges and Vertices in constant time, so for example each Vertex object should have a Locator member that points to the position of its Vertex* in the vertexList. The way I first implemented this was by saving a list::iterator, as follows: vertexList.push_back(v); v->locator = --vertexList.end(); Then if I need to delete this vertex later, then rather than searching the whole vertexList for its pointer, I can call: vertexList.erase(v->locator); This works fine at first, but it seems that if enough changes (deletions) are made to the list, the iterators will become out-of-date and I get all sorts of iterator errors at runtime. This seems strange for a linked list, because it doesn't seem like you should ever need to re-allocate the remaining members of the list after deletions, but maybe the STL does this to optimize by keeping memory somewhat contiguous? In any case, I would appreciate it if anyone has any insight as to why this happens. Is there a standard way in C++ to implement a locator that will keep track of an element's position in a list without becoming obsolete? Much thanks, Jeff

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  • Java downcasting dilemma

    - by Shades88
    please have a look at this code here. class Vehicle { public void printSound() { System.out.print("vehicle"); } } class Car extends Vehicle { public void printSound() { System.out.print("car"); } } class Bike extends Vehicle{ public void printSound() { System.out.print("bike"); } } public class Test { public static void main(String[] args) { Vehicle v = new Car(); Bike b = (Bike)v; v.printSound(); b.printSound(); Object myObj = new String[]{"one", "two", "three"}; for (String s : (String[])myObj) System.out.print(s + "."); } } Executing this code will give ClassCastException saying inheritance.Car cannot be cast to inheritance.Bike. Now look at the line Object myObj = new String[]{"one", "two", "three"};. This line is same as Vehicle v = new Car(); right? In both lines we are assigning sub class object to super class reference variable. But downcasting String[]myObj is allowed but (Bike)v is not. Please help me understand what is going on around here.

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  • Put together tiles in android sdk and use as background

    - by Jon
    In a feeble attempt to learn some Android development am I stuck at graphics. My aim here is pretty simple: Take n small images and build a random image, larger than the screen with possibility to scroll around. Have an animated object move around on it I have looked at the SDK examples, Lunar Lander especially but there are a few things I utterly fail to wrap my head around. I've got a birds view plan (which in my head seems reasonably sane): How do I merge the tiles into one large image? The background is static so I figure I should do like this: Make a 2d array with refs to the tiles Make a large Drawable and draw the tiles on it At init draw this big image as the background At each onDraw redraw the background of the previous spot of the moving object, and the moving object at its new location The problem is the hands on things. I load the small images with "Bitmap img1 = BitmapFactory.decodeResource (res, R.drawable.img1)", but then what? Should I make a canvas and draw the images on it with "canvas.drawBitmap (img1, x, y, null);"? If so how to get a Drawable/Bitmap from that? I'm totally lost here, and would really appreciate some hands on help (I would of course be grateful for general hints as well, but I'm primarily trying to understand the Graphics objects). To make you, dear reader, see my level of confusion will I add my last desperate try: Drawable drawable; Canvas canvas = new Canvas (); Bitmap img1 = BitmapFactory.decodeResource (res, R.drawable.img1); // 50 x 100 px image Bitmap img2 = BitmapFactory.decodeResource (res, R.drawable.img2); // 50 x 100 px image canvas.drawBitmap (img1, 0, 0, null); canvas.drawBitmap (img2, 50, 0, null); drawable.draw (canvas); // obviously wrong as draw == null this.setBackground (drawable); Thanks in advance

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  • Checking instance of non-class constrained type parameter for null in generic method

    - by casperOne
    I currently have a generic method where I want to do some validation on the parameters before working on them. Specifically, if the instance of the type parameter T is a reference type, I want to check to see if it's null and throw an ArgumentNullException if it's null. Something along the lines of: // This can be a method on a generic class, it does not matter. public void DoSomething<T>(T instance) { if (instance == null) throw new ArgumentNullException("instance"); Note, I do not wish to constrain my type parameter using the class constraint. I thought I could use Marc Gravell's answer on "How do I compare a generic type to its default value?", and use the EqualityComparer<T> class like so: static void DoSomething<T>(T instance) { if (EqualityComparer<T>.Default.Equals(instance, null)) throw new ArgumentNullException("instance"); But it gives a very ambiguous error on the call to Equals: Member 'object.Equals(object, object)' cannot be accessed with an instance reference; qualify it with a type name instead How can I check an instance of T against null when T is not constrained on being a value or reference type?

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  • Visual Studio crashes consistently on web-related projects

    - by Traveling Tech Guy
    Hi, I have a brand new VS2010 installed on a Win2008R2 machine. I started getting this error when debugging a WCF service project: "Attempted to read or write protected memory. This is often an indication that other memory is corrupt." When I started developing a web site a week later, this became consistent - I can't debug it. The stack dump reads: at Microsoft.VisualStudio.WebHost.Host.ProcessRequest(Connection conn) at Microsoft.VisualStudio.WebHost.Server.OnSocketAccept(Object acceptedSocket) at System.Threading.QueueUserWorkItemCallback.WaitCallback_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.QueueUserWorkItemCallback.System.Threading.IThreadPoolWorkItem.ExecuteWorkItem() at System.Threading.ThreadPoolWorkQueue.Dispatch() at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback() I tried searching online, and some recommend turning off the "Suppress JIT Optimizations" in the Debugging options - this dos not seem to make a difference. Clearly the problem is with the built in web server. But am I doing something wrong? Is there something I can do? Or is this a known bug? Thanks for your time, Guy Update 12/31: Today I tried using CassiniDev as a replacement to the original VS2010 WebServer - exact same result. My suspicion is that there's some internal conflict between VS2010, Windows Server 2008R2 and maybe the fact that it's a 64 bit OS. I switched to using IIS as my debug server - and that seems to work, with some annoying side effects. My conclusion: do not use a 64 bit server system as your dev machine. Develop on 32bit - deploy to 64bit. Side conclusion: there are some scenarios Microsoft's QA doesn't test.

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  • How to fetch populated associated models in CakePHP when calling read()

    - by Code Commander
    I have the following Models: class Site extends AppModel { public $name = "Site"; public $useTable = "site"; public $primaryKey = "id"; public $displayField = 'name'; public $hasMany = array('Item' => array('foreignKey' => 'siteId')); public function canView($userId, $isAdmin = false) { if($isAdmin) { return true; } return array_key_exists($this->id, $allowedSites); } } and class Item extends AppModel { public $name = "Item"; public $useTable = "item"; public $primaryKey = "id"; public $displayField = 'name'; public $belongsTo = array('Site' => array('foreignKey' => 'siteId')); public function canView($userId, $isAdmin = false) { // My problem appears to be the next line: return $this->Site->canView($userId, $isAdmin); } } In my controller I am doing something like this: $result = $this->Item->read(null, $this->request->id); // Verify permissions if(!$this->Item->canView($this->Session->read('userId'), $this->Session->read('isAdmin'))) { $this->httpCodes(403); die('Permission denied.'); } I notice that in Item->canView() $this->data['Site'] is populated with the column data from the site table. But it merely an array and not an object. On the other hand $this->Site is a Site object, but it has not been populated with the column data from the site table like $this->data. What is the proper way to have CakePHP get the associated model as the object and containing the data? Or am I going about this all wrong? Thanks!

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  • Implementation of delegates in C#

    - by Ram
    Hi, I am trying to learn on how to use delegates efficiently in C# and I was just wondering if anyone can guide me through... The following is a sample implementation using delegates... All I am doing is just passing a value through a delegate from one class to another... Please tell me if this is the right way to implement... And also your suggestions... Also, please note that I have de-registered the delegate in : void FrmSample_FormClosing(object sender, FormClosingEventArgs e) { sampleObj.AssignValue -= new Sample.AssignValueDelegate(AssignValue); } Is this de-registration necessary? The following is the code that I have written.. public partial class FrmSample : Form { Sample sampleObj; public FrmSample() { InitializeComponent(); this.Load += new EventHandler(FrmSample_Load); this.FormClosing += new FormClosingEventHandler(FrmSample_FormClosing); sampleObj = new Sample(); sampleObj.AssignValue = new Sample.AssignValueDelegate(AssignValue); } void FrmSample_FormClosing(object sender, FormClosingEventArgs e) { sampleObj.AssignValue -= new Sample.AssignValueDelegate(AssignValue); } void FrmSample_Load(object sender, EventArgs e) { sampleObj.LoadValue(); } void AssignValue(string value) { MessageBox.Show(value); } } class Sample { public delegate void AssignValueDelegate(string value); public AssignValueDelegate AssignValue; internal void LoadValue() { if (AssignValue != null) { AssignValue("This is a test message"); } } } Pls provide your feedback on whether this is right... Thanks, Ram

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