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  • NoMethodError / undefined method `foobar_path' when using form_for

    - by user1850886
    I'm using form_for to create a chatroom and when I view the page I get the following error: NoMethodError in Chatrooms#new undefined method `chatrooms_path' for #<#<Class:0xa862b94>:0xa5307f0> Here's the code for the view, located in app/views/chatrooms/new.html.erb: <div class="center"> <%= form_for(@chatroom) do |f| %> <%=f.text_field :topic%> <br> <%=f.submit "Start a discussion", class: "btn btn-large btn-primary"%> <% end %> </div> Here's the relevant controller: class ChatroomsController < ApplicationController def new @chatroom = Chatroom.new end def show @chatroom = Chatroom.find(params[:id]) end end If I change the line <%= form_for(@chatroom) do |f| %> to <%= form_for(:chatroom) do |f| %> it works fine. I've searched around for similar questions but none of the solutions have worked for me. Help?

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  • C# / this. and List<T>

    - by user3533030
    I am having trouble understanding how to initialize a List of objects and use it with methods inside of a class. I understand the mechanics of the List, but not how to initialize it inside a method and use it later. For example, I want to have a class that creates the List when it is constructed. Then, I want to use a method of that class to add elements to the list. The elements in the list are objects defined by the SolidWorks API. So, to construct the List, I used... public class ExportPoints : Exporter { public List<SldWorks.SketchPoint> listOfSketchPoints; public ExportPoints(SldWorks.SldWorks swApp, string nameSuffix) : base(swApp, nameSuffix) { List<SldWorks.SketchPoint> listOfSketchPoints = new List<SldWorks.SketchPoint>(); } public void createListOfFreePoints() { try { [imagine more code here] this.listOfSketchPoints.Add(pointTest); } catch (Exception e) { Debug.Print(e.ToString()); return; } } This fails during execution as if the listOfSketchPoints was never initialized as a List. So, I tried a hack and this worked: public ExportPoints(SldWorks.SldWorks swApp, string nameSuffix) : base(swApp, nameSuffix) { List<SldWorks.SketchPoint> listOfSketchPoints = new List<SldWorks.SketchPoint>(); this.listOfSketchPoints = listOfSketchPoints; } This approach creates the behavior that I want. However, it seems that I lack some understanding as to why this is necessary. Shouldn't it be possible to "initialize" a List that is a property of your object with a constructor? Why would you need to create the list, then assign the pointer of that new List to your property?

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  • How to determine number of function arguments dynamically

    - by Kam
    I have the following code: #include <iostream> #include <functional> class test { public: typedef std::function<bool(int)> Handler; void handler(Handler h){h(5);} }; class test2 { public: template< typename Ret2, typename Ret, typename Class, typename Param> inline Ret2 MemFn(Ret (Class::*f)(Param), int arg_num) { if (arg_num == 1) return std::bind(f, this, std::placeholders::_1); } bool f(int x){ std::cout << x << std::endl; return true;} }; int main() { test t; test2 t2; t.handler(t2.MemFn<test::Handler>(&test2::f, 1)); return 0; } It works as expected. I would like to be able to call this: t.handler(t2.MemFn<test::Handler>(&test2::f)); instead of t.handler(t2.MemFn<test::Handler>(&test2::f, 1)); Basically I need MemFn to determine in runtime what Handler expects as the number of arguments. Is that even possible?

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  • Has anyone used ever Mangoslick from themeforest?

    - by bonesnatch
    I was assigned to integrate MangoSlick theme to our current admin panel, Its a jQuery, Slick(?) and Responsive template. First, let me explain how the API goes In the documentation, it only says this is the only way data-[options]=[value] Example: If I wanna make a progress bar I can use this format <div class="progress"> <div class="bar" data-title="[title]" data-value="[value]" data-max="[max]" data-format="[format string]"></div> </div> so filling-in values <div class="progress"> <div class="bar" data-title="Space" data-value="1285" data-max="5120" data-format="0,0 MB"></div> </div> I will have this as output Now, the main question is when I use jQuery attr() to change the attribute values for data-title, data-max, data-value and data-format. Why is it not working? <script> var jq = $.noConflict(); jq(document).ready(function(){ jq('#bokz').attr("data-title", "No Space"); }); </script> Using the script above and inspect element in chrome the values are changed but not in the progressbar Some of you may have some ideas on this? Any help/suggestion would be very much appreciated.

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  • Creating a assertClass() method in JUnit

    - by Mike
    Hi, I'm creating a test platform for a protocol project based on Apache MINA. In MINA when you receive packets the messageReceived() method gets an Object. Ideally I'd like to use a JUnit method assertClass(), however it doesn't exist. I'm playing around trying to work out what is the closest I can get. I'm trying to find something similar to instanceof. Currently I have: public void assertClass(String msg, Class expected, Object given) { if(!expected.isInstance(given)) Assert.fail(msg); } To call this: assertClass("Packet type is correct", SomePacket.class, receivedPacket); This works without issue, however in experimenting and playing with this my interest was peaked by the instanceof operator. if (receivedPacket instanceof SomePacket) { .. } How is instanceof able to use SomePacket to reference the object at hand? It's not an instance of an object, its not a class, what is it?! Once establishing what type SomePacket is at that point is it possible to extend my assertClass() to not have to include the SomePacket.class argument, instead favouring SomePacket?

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  • Background-image is not displaying in Firefox

    - by goa
    Strange thing happens. Background-image is not displaying in Firefox under some versions of WindowsXP and Windows Vista, but displays in Firefox under Mac OSX. It also displays in IE. This is CSS: .cherry_banner { background: url("library/media/images/cherry_banner_top.png") no-repeat; width: 276px; display:block; min-height:100px; padding-top: 13px; color: #fdfdfd; margin-bottom:20px; } .cherry_banner a { color: #fdfdfd; } .cherry_banner a:hover { text-decoration:underline; } .cherry_banner li { list-style-type:none; } .cherry_banner h2 { font-size: 18px; margin-bottom: 10px; } .chb_text1 { background: url("library/media/images/cherry_banner_pixel.png") repeat-y; } .chb_text2 { background: url("library/media/images/cherry_banner_bottom.gif") bottom no-repeat; padding: 4px 14px 24px 25px; } And this is html: <div id="linkcat-8" class="cherry_banner tpt"><div class="chb_text1"><div class="chb_text2"> <h2>??? ?????????</h2> <ul class='xoxo blogroll'> <li><a href="http://inveda.ru/jyotish/naksatra-calendar/">???????? ?????????? ?????????????? ????????? ????????????? ??? ?? 2010?.</a></li> </ul> </div></div></div> You can see on http://www.inveda.ru - right column - red banner.

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  • PHP: cannot matching string "<br />

    - by Patrick
    hi, I'm having problems with string matching in PHP. I've 2 html elements in my page, I've copy pasted here the content with Firebug <div class="field-item odd"> <div class="field-label-inline-first"> Year:</div> 2009 </div> <div class="field-item odd"> <div class="field-label-inline-first"> Synopsis:</div> &lt;br /&gt; </div> This php line works perfectly (the element with 2009 is detected) <?php if ($items[0]['view'] == '2009') : echo "ok"; ?> However I'm not able to match the string containing element: <?php if ($items[0]['view'] == '<br />') : echo "ok"; ?> //doesn't work <?php if ($items[0]['view'] == '&lt;br /&gt;') : echo "ok"; ?> //again doesn't work any tip ? To give you some context: The strings are produced by CKEditor, an editor I'm using in my Drupal back-end. When I leave empty this editor, the tag is displayed on the string as plain text (because I set "plain text" as formatting option in the back-end) Thanks

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  • Hibernate many-to-many relationship

    - by Capitan
    I have two mapped types, related many-to-many. @Entity @Table(name = "students") public class Student{ ... @ManyToMany(fetch = FetchType.EAGER) @JoinTable( name = "students2courses", joinColumns = { @JoinColumn( name = "student_id", referencedColumnName = "_id") }, inverseJoinColumns = { @JoinColumn( name = "course_id", referencedColumnName = "_id") }) public Set<Course> getCourses() { return courses; } public void setCourses(Set<Course> courses) { this.courses = courses; } ... } __ @Entity @Table(name = "courses") public class Course{ ... @ManyToMany(fetch = FetchType.EAGER, mappedBy = "courses") public Set<Student> getStudents() { return students; } public void setStudents(Set<Student> students) { this.students = students; } ... } But if I update/delete Course entity, records are not created/deleted in table students2courses. (with Student entity updating/deleting goes as expected) I wrote abstract class HibObject public abstract class HibObject { public String getRemoveMTMQuery() { return null; } } which is inherited by Student and Course. In DAO I added this code (for delete() method): String query = obj.getRemoveMTMQuery(); if (query != null) { session.createSQLQuery(query).executeUpdate(); } and I ovrerided method getRemoveMTMQuery() for Course @Override @Transient public String getRemoveMTMQuery() { return "delete from students2courses where course_id = " + id + ";"; } Now it works but I think it's a bad code. Is there a best way to solve this problem?

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  • How does a java compiler resolve a non-imported name

    - by gexicide
    Consider I use a type X in my java compilation unit from package foo.bar and X is not defined in the compilation unit itself nor is it directly imported. How does a java compiler resolve X now efficiently? There are a few possibilities where X could reside: X might be imported via a star import a.b.* X might reside in the same package as the compilation unit X might be a language type, i.e. reside in java.lang The problem I see is especially (2.). Since X might be a package-private type, it is not even required that X resides in a compilation unit that is named X.java. Thus, the compiler must look into all entries of the class path and search for any classes in a package foo.bar, it then must read every class that is in package foo.bar to check whether X is included. That sounds very expensive. Especially when I compile only a single file, the compiler has to read dozens of class files only to find a type X. If I use a lot of star imports, this procedure has to be repeated for a lot of types (although class files won't be read twice, of course). So is it advisable to import also types from the same package to speed up the compilation process? Or is there a faster method for resolving an unimported type X which I was not able to find?

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  • How do I implement IEnumerable?

    - by Stacey
    I have a class that contains a static number of objects. This class needs to be frequently 'compared' to other classes that will be simple List objects. public partial class Sheet { public Item X{ get; set; } public Item Y{ get; set; } public Item Z{ get; set; } } the items are obviously not going to be "X" "Y" "Z", those are just generic names for example. The problem is that due to the nature of what needs to be done, a List won't work; even though everything in here is going to be of type Item. It is like a checklist of very specific things that has to be tested against in both code and runtime. This works all fine and well; it isn't my issue. My issue is iterating it. For instance I want to do the following... List<Item> UncheckedItems = // Repository Logic Here. UncheckedItems contains all available items; and the CheckedItems is the Sheet class instance. CheckedItems will contain items that were moved from Unchecked to Checked; however due to the nature of the storage system, items moved to Checked CANNOT be REMOVED from Unchecked. I simply want to iterate through "Checked" and remove anything from the list in Unchecked that is already in "Checked". So naturally, that would go like this with a normal list. foreach(Item item in Unchecked) { if( Checked.Contains(item) ) Unchecked.Remove( item ); } But since "Sheet" is not a 'List', I cannot do that. So I wanted to implement IEnumerable so that I could. Any suggestions? I've never implemented IEnumerable directly before and I'm pretty confused as to where to begin.

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  • How to insert rows in a many-to-many relationship

    - by GSound
    Hello, I am having an issue trying to save into an intermediate table. I am new on Rails and I have spent a couple of hours on this but can't make it work, maybe I am doing wrong the whole thing. Any help will be appreciated. =) The app is a simple book store, where a logged-in user picks books and then create an order. This error is displayed: NameError in OrderController#create uninitialized constant Order::Orderlist These are my models: class Book < ActiveRecord::Base has_many :orderlists has_many :orders, :through => :orderlists end class Order < ActiveRecord::Base belongs_to :user has_many :orderlists has_many :books, :through => :orderlists end class OrderList < ActiveRecord::Base belongs_to :book belongs_to :order end This is my Order controller: class OrderController < ApplicationController def add if session[:user] book = Book.find(:first, :conditions => ["id = #{params[:id]}"]) if book session[:list].push(book) end redirect_to :controller => "book" else redirect_to :controller => "user" end end def create if session[:user] @order = Order.new if @order.save session[:list].each do |b| @order.orderlists.create(:book => b) # <-- here is my prob I cant make it work end end end redirect_to :controller => "book" end end Thnx in advance! Manuel

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  • Reference properteries declared in a protocol and implemented in the anonymous category?

    - by Heath Borders
    I have the following protocol: @protocol MyProtocol @property (nonatomic, retain) NSObject *myProtocolProperty; -(void) myProtocolMethod; @end and I have the following class: @interface MyClass : NSObject { } @end I have a class extension declared, I have to redeclare my protocol properties here or else I can't implement them with the rest of my class. @interface()<MyProtocol> @property (nonatomic, retain) NSObject *myExtensionProperty; /* * This redeclaration is required or my @synthesize myProtocolProperty fails */ @property (nonatomic, retain) NSObject *myProtocolProperty; - (void) myExtensionMethod; @end @implementation MyClass @synthesize myProtocolProperty = _myProtocolProperty; @synthesize myExtensionProperty = _myExtensionProperty; - (void) myProtocolMethod { } - (void) myExtensionMethod { } @end In a consumer method, I can call my protocol methods and properties just fine. Calling my extension methods and properties produces a warning and an error respectively. - (void) consumeMyClassWithMyProtocol: (MyClass<MyProtocol> *) myClassWithMyProtocol { myClassWithMyProtocol.myProtocolProperty; // works, yay! [myClassWithMyProtocol myProtocolMethod]; // works, yay! myClassWithMyProtocol.myExtensionProperty; // compiler error, yay! [myClassWithMyProtocol myExtensionMethod]; // compiler warning, yay! } Is there any way I can avoid redeclaring the properties in MyProtocol within my class extension in order to implement MyProtocol privately?

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  • Hiding instantiated templates in shared library created with g++

    - by jchl
    I have a file that contains the following: #include <map> class A {}; void doSomething() { std::map<int, A> m; } When compiled into a shared library with g++, the library contains dynamic symbols for all the methods of std::map<int, A>. Since A is private to this file, there is no possibility that std::map will be instantiated in any other shared library with the same parameters, so I'd like to make the template instantiation hidden (for some of the reasons described in this document). I thought I should be able to do this by adding an explicit instantiation of the template class and marking it as hidden, like so: #include <map> class A {}; template class __attribute__((visibility ("hidden"))) std::map<int, A>; void doSomething() { std::map<int, A> m; } However, this has no effect: the symbols are still all exported. I even tried compiling with -fvisibility=hidden, but this also has no effect on the visibility of the methods of std::map<int, A> (although it does hide doSomething). The document I linked to above describes the use of export maps to restrict visibility, but that seems very tedious. Is there a way to do what I want in g++ (other than using export maps)? If so, what is it? If not, is there a good reason why these symbols must always be exported, or is this just a omission in g++?

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  • Unit Tests Architecture Question

    - by Tom Tresansky
    So I've started to layout unit tests for the following bit of code: public interface MyInterface { void MyInterfaceMethod1(); void MyInterfaceMethod2(); } public class MyImplementation1 implements MyInterface { void MyInterfaceMethod1() { // do something } void MyInterfaceMethod2() { // do something else } void SubRoutineP() { // other functionality specific to this implementation } } public class MyImplementation2 implements MyInterface { void MyInterfaceMethod1() { // do a 3rd thing } void MyInterfaceMethod2() { // do something completely different } void SubRoutineQ() { // other functionality specific to this implementation } } with several implementations and the expectation of more to come. My initial thought was to save myself time re-writing unit tests with something like this: public abstract class MyInterfaceTester { protected MyInterface m_object; @Setup public void setUp() { m_object = getTestedImplementation(); } public abstract MyInterface getTestedImplementation(); @Test public void testMyInterfaceMethod1() { // use m_object to run tests } @Test public void testMyInterfaceMethod2() { // use m_object to run tests } } which I could then subclass easily to test the implementation specific additional methods like so: public class MyImplementation1Tester extends MyInterfaceTester { public MyInterface getTestedImplementation() { return new MyImplementation1(); } @Test public void testSubRoutineP() { // use m_object to run tests } } and likewise for implmentation 2 onwards. So my question really is: is there any reason not to do this? JUnit seems to like it just fine, and it serves my needs, but I haven't really seen anything like it in any of the unit testing books and examples I've been reading. Is there some best practice I'm unwittingly violating? Am I setting myself up for heartache down the road? Is there simply a much better way out there I haven't considered? Thanks for any help.

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  • The cross-thread usage of "HttpContext.Current" property and related things

    - by smwikipedia
    I read from < Essential ASP.NET with Examples in C# the following statement: Another useful property to know about is the static Current property of the HttpContext class. This property always points to the current instance of the HttpContext class for the request being serviced. This can be convenient if you are writing helper classes that will be used from pages or other pipeline classes and may need to access the context for whatever reason. By using the static Current property to retrieve the context, you can avoid passing a reference to it to helper classes. For example, the class shown in Listing 4-1 uses the Current property of the context to access the QueryString and print something to the current response buffer. Note that for this static property to be correctly initialized, the caller must be executing on the original request thread, so if you have spawned additional threads to perform work during a request, you must take care to provide access to the context class yourself. I am wondering about the root cause of the bold part, and one thing leads to another, here is my thoughts: We know that a process can have multiple threads. Each of these threads have their own stacks, respectively. These threads also have access to a shared memory area, the heap. The stack then, as I understand it, is kind of where all the context for that thread is stored. For a thread to access something in the heap it must use a pointer, and the pointer is stored on its stack. So when we make some cross-thread calls, we must make sure that all the necessary context info is passed from the caller thread's stack to the callee thread's stack. But I am not quite sure if I made any mistake. Any comments will be deeply appreciated. Thanks. ADD Here the stack is limited to user stack.

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  • Dynamically adding custom view to RemoteViews

    - by Naidu
    Could any help me to do this?My code is like: public CustomClass extends View { //uses ondraw() to do something } For displaying my custom view on HomeScreen i created a class to extend Broadcast Receiver public class customAppWidgetProvider extends BroadcastReceiver { public void onReceive(Context context, Intent intent) { String action = intent.getAction(); if (AppWidgetManager.ACTION_APPWIDGET_UPDATE.equals(action)) { RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.main); //Here i want to create my custom view class object and i want to add this view to linear layout in main.xml CustomClass object = new CustomClass(context) ; LinearLayout layout = new LinearLayout(context) ; layout.setLayoutParameters(new LayoutParameters(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT)); layout.addView(object); views.addview(R.id.linearlayout, (ViewGroup) layout) ; views.setOnClickPendingIntent(R.id.analog_appwidget, PendingIntent.getActivity(context, 0, new Intent(context, AlarmClock.class), PendingIntent.FLAG_CANCEL_CURRENT)); int[] appWidgetIds = intent.getIntArrayExtra( AppWidgetManager.EXTRA_APPWIDGET_IDS); AppWidgetManager gm = AppWidgetManager.getInstance(context); gm.updateAppWidget(appWidgetIds, views); } } } But adding viewgroup to RemoteView reference is not working... above main.xml contains only LinearLayout.I want to add custom view object to it.But after running this not showing anything on screen.. please help me to do this.Thanks in Advance.

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  • junit test error - ClassCastException

    - by Josepth Vodary
    When trying to run a junit test I get the following error - java.lang.ClassCastException: business.Factory cannot be cast to services.itemservice.IItemsService at business.ItemManager.get(ItemManager.java:56) at business.ItemMgrTest.testGet(ItemMgrTest.java:49) The specific test that is causing the problem is @Test public void testGet() { Assert.assertTrue(itemmgr.get(items)); } The code it is testing is... public boolean get(Items item) { boolean gotItems = false; Factory factory = Factory.getInstance(); @SuppressWarnings("static-access") IItemsService getItem = (IItemsService)factory.getInstance(); try { getItem.getItems("pens", 15, "red", "gel"); gotItems = true; } catch (ItemNotFoundException e) { // catch e.printStackTrace(); System.out.println("Error - Item Not Found"); } return gotItems; } The test to store items, which is nearly identical, works just fine... The factory class is.. public class Factory { private Factory() {} private static Factory Factory = new Factory(); public static Factory getInstance() {return Factory;} public static IService getService(String serviceName) throws ServiceLoadException { try { Class<?> c = Class.forName(getImplName(serviceName)); return (IService)c.newInstance(); } catch (Exception e) { throw new ServiceLoadException(serviceName + "not loaded"); } } private static String getImplName (String serviceName) throws Exception { java.util.Properties props = new java.util.Properties(); java.io.FileInputStream fis = new java.io.FileInputStream("config\\application.properties"); props.load(fis); fis.close(); return props.getProperty(serviceName); } }

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  • Error while setting UserAcces permission for WebForms?

    - by ksg
    I've created a class named BaseClass.cs and I've written a function in its constructor. Here's how it looks public class BasePage:Page { public BasePage() { setUserPermission(); } private void setUserPermission() { String strPathAndQuery = HttpContext.Current.Request.Url.PathAndQuery; string strulr = strPathAndQuery.Replace("/SGERP/", "../"); Session["Url"] = strulr; GEN_FORMS clsForm = new GEN_FORMS(); clsForm.Form_Logical_Name = Session["Url"].ToString(); clsForm.User_ID = Convert.ToInt32(Session["User_ID"]); DataSet dsPermission = clsForm.RETREIVE_BUTTON_PERMISSIONS(); if (dsPermission.Tables.Count > 0) { if (dsPermission.Tables[1].Rows.Count > 0) { Can_Add = Convert.ToBoolean(dsPermission.Tables[1].Rows[0]["Can_Add"].ToString()); Can_Delete = Convert.ToBoolean(dsPermission.Tables[1].Rows[0]["Can_Delete"].ToString()); Can_Edit = Convert.ToBoolean(dsPermission.Tables[1].Rows[0]["Can_Edit"].ToString()); Can_Print = Convert.ToBoolean(dsPermission.Tables[1].Rows[0]["Can_Print"].ToString()); Can_View = Convert.ToBoolean(dsPermission.Tables[1].Rows[0]["Can_Print"].ToString()); } } } } I've inherited this class on my webform so that when the page loads, the setUserPermission function is executed. My webpage looks like this public partial class Setting_CompanyDetails : BasePage My problem is that I cannot access Session["Url"] in my BasePage. I'm getting the following error Session state can only be used when enableSessionState is set to true, either in a configuration file or in the Page directive. Please also make sure that System.Web.SessionStateModule or a custom session state module is included in the <configuration>\<system.web>\<httpModules> section in the application configuration. How can I solve this issue? Is this the right way to set UserPermission access?

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  • Flash Builder 4 "includeIn" property causing design view error

    - by Chris
    I am creating a custom TextInput component that will define an "error" state. I have extended the TextInput class to change the state to "error" if the errorString property's length is greater than 0. In the skin class, I have defined an "error" state, and added some logic to detect the size and position of the error icon. However, if I have this code at the same time I use the "includeIn" property in the bitmap image tag, I get a design view error. If I either A) Only include that code with no "includeIn" property set, it works or B) dont include the code to set the icon size and position and only use the "includeIn" property, it works. Any ideas what could be causing the design view problem when I use both the "includeIn" property and the icon size/position code at the same time? TextInput Class: package classes { import spark.components.TextInput; public class TextInput extends spark.components.TextInput { [SkinState("error")]; public function TextInput() { super(); } override public function set errorString( value:String ):void { super.errorString = value; invalidateSkinState(); } override protected function getCurrentSkinState():String { if (errorString.length>0) { return "error"; } return super.getCurrentSkinState(); } } } TextInput Skin File: override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void { //THIS IS THE CODE THAT SEEMS TO BE CAUSING THE PROBLEM if(getStyle("iconSize") == "large") { errorIcon.right = -12; errorIcon.source = new errorIconLg(); } else { errorIcon.right = -5; errorIcon.source = new errorIconSm(); } super.updateDisplayList(unscaledWidth, unscaledHeight); } </fx:Script> <s:states> <s:State name="normal"/> <s:State name="disabled"/> <s:State name="error"/> </s:states> //If I remove the problem code above or if I take out the includeIn //property here, it works <s:BitmapImage id="errorIcon" verticalCenter="0" includeIn="error" /> </s:SparkSkin>

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  • C++ const qualifier

    - by avd
    I have a Point2D class as follows: class Point2D{ int x; int y; public: Point2D(int inX, int inY){ x = inX; y = inY; }; int getX(){return x;}; int getY(){return y;}; }; Now I have defined a class Line as: class Line { Point2D p1,p2; public: LineVector(const Point2D &p1,const Point2D &p2):p1(p1),p2(p2) { int x1,y1,x2,y2; x1=p1.getX();y1=p1.getY();x2=p2.getX();y2=p2.getY(); } }; Now the compiler gives the error in the last line( where getX() etc are called): error: passing `const Point2D' as `this' argument of `int Point2D::getX()' discards qualifiers If I remove the const keyword at both places, then it compiles successfully. What is the error? Is it because getX() etc are defined inline? Is there any way to recify this retaining them inline?

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  • Rails active record association problem

    - by Harm de Wit
    Hello, I'm new at active record association in rails so i don't know how to solve the following problem: I have a tables called 'meetings' and 'users'. I have correctly associated these two together by making a table 'participants' and set the following association statements: class Meeting < ActiveRecord::Base has_many :participants, :dependent => :destroy has_many :users, :through => :participants and class Participant < ActiveRecord::Base belongs_to :meeting belongs_to :user and the last model class User < ActiveRecord::Base has_many :participants, :dependent => :destroy At this point all is going well and i can access the user values of attending participants of a specific meeting by calling @meeting.users in the normal meetingshow.html.erb view. Now i want to make connections between these participants. Therefore i made a model called 'connections' and created the columns of 'meeting_id', 'user_id' and 'connected_user_id'. So these connections are kinda like friendships within a certain meeting. My question is: How can i set the model associations so i can easily control these connections? I would like to see a solution where i could use @meeting.users.each do |user| user.connections.each do |c| <do something> end end I tried this by changing the model of meetings to this: class Meeting < ActiveRecord::Base has_many :participants, :dependent => :destroy has_many :users, :through => :participants has_many :connections, :dependent => :destroy has_many :participating_user_connections, :through => :connections, :source => :user Please, does anyone have a solution/tip how to solve this the rails way?

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  • C++ - Creating a god object

    - by Greg Kritzman
    Hypothetical situation that I'm struggling to get my head past. HoldsFooBar.h: #include "foo.h" #include "bar.h" class HoldsFooBar{ foo F; bar B; }; foo.h: //includes? class foo{ HoldsFooBar *H; void Baz(); }; bar.h: //includes? class bar{ HoldsFooBar *H; void Qux(); }; I'm trying to get F to get a hold of B. In all other languages I've worked with, I would be able to H->B.Qux();, but I'm totally lost in C++. At the includes lines in foo.h and bar.h, it seems like my options are to forward-declare class HoldsFooBar; but then I can only access H, and F and B cannot see each other. Likewise, I can #include "HoldsFooBar.h" but because of my include guards, something ends up not getting linked properly, so the program doesn't run. Is what I'm trying to do even possible? Thank you very much! Any help would be appreciated!

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  • VB.NET: WithEvents not Working

    - by Hei
    Hello All, I have the following classes: Public Class Email Private Shared ReadOnly EMAIL_REGEX = "\b[a-zA-Z]+[a-zA-Z0-9._+-]+@" + _ "[a-zA-Z0-9.-]+\.[a-zA-Z]{2,3}\b" Private _email As String Public Event emailCreated() ' Declare empty constructor private so the only way to create an object ' is using new (email) Private Sub New() End Sub Sub New(ByVal email As String) If Regex.IsMatch(email, EMAIL_REGEX) Then _email = email RaiseEvent emailCreated() Else Throw New Exception("Email Not Valid") End If End Sub ReadOnly Property Email() As String Get Return _email End Get End Property End Class And Public Class EmailForm WithEvents myEmail As Email Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Try myEmail = New Email(TextBox1.Text) Catch ex As Exception MessageBox.Show("Exception: " & ex.Message) End Try End Sub Public Sub emailCreated() Handles myEmail.emailCreated MessageBox.Show("New Email Created") End Sub End Class If a create a wrong email lets say "email" the exception is correctly cached and a message is showed however is i input a valid email the event is not raised, the object is being created but no message is shown and no error or exception is thrown i suspect it has something to do with using "myemail = new Email(email)" but i have seen examples of using new with withevents with no problem. I would apreciate any input about this problem thank you

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  • How do I code a tree of objects in Haskell with pointers to parent and children?

    - by axilmar
    I've got the following problem: I have a tree of objects of different classes where an action in the child class invalidates the parent. In imperative languages, it is trivial to do. For example, in Java: public class A { private List<B> m_children = new LinkedList<B>(); private boolean m_valid = true; public void invalidate() { m_valid = false; } public void addChild(B child) { m_children.add(child); child.m_parent = this; } } public class B { public A m_parent = null; private int m_data = 0; public void setData(int data) { m_data = 0; m_parent.invalidate(); } } public class Main { public static void main(String[] args) { A a = new A(); B b = new B(); b.setData(0); //invalidates A } } How do I do the above in Haskell? I cannot wrap my mind around this, since once I construct an object in Haskell, it cannot be changed. I would be much obliged if the relevant Haskell code is posted.

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  • Page does update with details from the database after i hit a button

    - by swathi
    I have a code and the way it should work is,when they click on NEW CUSTOMER,it takes them to test1.php where in they enter the details and they hit submit.it saves all the details in properly in the database and when i go back and hit REFRESH ,it should come up with the customer details which they had entered in previously. But what happens is, when i click on the REFRESH,it refreshes the same old page which is empty.I wanted to find out where am i missing the logic.Thanks in advance. The sample code would be <tr> <td class="tdvisitbig" colspan="5">THIS IS A TEST</td> </tr> <tr> <td class='tdvisitbig' colspan="5"><input type="button" onClick="openVisit('test1.php?id=<?=$key?>&name=<?=$name?>');return false;" value="NEW CUSTOMER" class="submit">&nbsp;<input type="button" value="REFRESH" name="add_xyz" class="submit" onClick="document.add.target='_self';document.add.action='test3.php?redirect=visit&section=test page';document.add.submit();"></td> </tr> <? $q = "SELECT address,customernum,status FROM customer WHERE name='$name' ORDER BY customernum"; $r = mysql_query( $q , $Link ); while( $rw = mysql_fetch_assoc( $r ) ) { extract( $rw ); ?> <tr> <? } ?>

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