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• Get notified/receive explicit intents when an activity starts

  - by qtips

  Hi, I am developing an application than gets notified when an activity chosen by a user is started. For this to work, the best approach would be to register a broadcastreceiver for ACTION_MAIN explicit intents, which as far as I know doesn't work (because these intents have specific targets). Another, probably less efficient approach, is to use the system ActivityManager and poll on the getRunningTask() which returns a list of all running tasks at the moment. The polling can be done by a background service. By monitoring the changes in this list, I can see whether an activity is running or not, so that my application can get notified. The downside is ofcourse the polling. I have not tried this yet, but I think that this last approach will probably work. Does anyone know of a better approach(es) or suggestions which are less intensive?

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• LLVM Clang 5.0 explicit in copy-initialization error

  - by kevzettler

  I'm trying to compile an open source project on OSX that has only been tested on Linux. $: g++ -v Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1 Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn) Target: x86_64-apple-da I'm trying to compile with the following command line options g++ -MMD -Wall -std=c++0x -stdlib=libc++ -Wno-sign-compare -Wno-unused-variable -ftemplate-depth=1024 -I /usr/local/Cellar/boost/1.55.0/include/boost/ -g -O3 -c level.cpp -o obj-opt/level.o I am seeing several errors that look like this: ./square.h:39:70: error: chosen constructor is explicit in copy-initialization int strength = 0, double flamability = 0, map<SquareType, int> constructions = {}, bool ticking = false); The project states the following are requirements for the Linux setup. How can I confirm I'm making that? gcc-4.8.2 git libboost 1.5+ with libboost-serialize libsfml-dev 2+ (Ubuntu ppa that contains libsfml 2: ) freeglut-dev libglew-dev

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• Type casting Collections using Conversion Operators

  - by Vyas Bharghava

  The below code gives me User-defined conversion must convert to or from enclosing type, while snippet #2 doesn't... It seems that a user-defined conversion routine must convert to or from the class that contains the routine. What are my alternatives? Explicit operator as extension method? Anything else? public static explicit operator ObservableCollection<ViewModel>(ObservableCollection<Model> modelCollection) { var viewModelCollection = new ObservableCollection<ViewModel>(); foreach (var model in modelCollection) { viewModelCollection.Add(new ViewModel() { Model = model }); } return viewModelCollection; } Snippet #2 public static explicit operator ViewModel(Model model) { return new ViewModel() {Model = model}; } Thanks in advance!

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• problem with for xml explicit clause in sql server 2005

  - by harrycode

  I am using for xml explicit clause in sql to send table data as xml from sql to asp.net page. I have created a stored procedure when i run store procedure in sql mgmt studio my xml is same as expected. But when I fetch It in asp.net then Xml returned is broken into two rows if xml exceeds certain character limit. I want result to be in single row. I am unable to figure out why single xml string is broken into two rows. please help

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• UDK "Error, Accessing a member of _'s within class through a context expression requires explicit 'O

  - by Ricket

  I get the following error in the UDK Frontend when I try to make my project: C:\UDK\UDK-2010-03\Development\Src\FixIt\Classes\ZInteraction.uc(58) : Error, Accessing a member of GameUISceneClient's within class through a context expression requires explicit 'Outer' The class ZInteraction extends Interaction. Line 58 is: GetSceneClient().ConsoleCommand("KEYNAME"@Key); What is the problem here? I am still investigating and I will update as I find out more. edit: Tried fixing the line up as class'UIRoot'.static.GetSceneClient().ConsoleCommand("KEYNAME"@Key); - no change.

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• VS 2008 irritating copy constructor link dependency

  - by Paul Hollingsworth

  Hi guys, I've run into the following annoying and seemingly incorrect behaviour in the Visual Studio 2008 C++ compiler: Suppose I have a class library - Car.lib - that uses a "Car" class, with a header called "Car.h": class Car { public: void Drive() { Accelerate(); } void Accelerate(); }; What I'm actually trying to do is use the Car headers (for some other functions), but without having to link with Car.lib itself (the actual class is not called "Car" but I am sanitising this example). If I #include "Car.h" in the .cpp file used to build a managed C++ .dll, but never refer to Car, everything compiles and links fine. This is because I never instantiate a Car object. However, the following: namespace { class Car { public: Car(const Car& rhs) { Accelerate(); } void Accelerate(); }; } leaves me with the link error: Error 2 error LNK2001: unresolved external symbol "public: void __thiscall `anonymous namespace'::Car::Accelerate(void)" (?Accelerate@Car@?A0xce3bb5ed@@$$FQAEXXZ) CREObjectWrapper.obj CREObjectBuilderWrapper Note I've declared the whole thing inside an anonymous namespace so there's no way that the Car functions could be exported from the .DLL in any case. Declaring the copy constructor out-of-line makes no difference. i.e. the following also fails to link: class Car { public: Car(const Car& rhs); void Accelerate(); }; Car::Car(const Car& rhs) { Accelerate(); } It's something specifically to do with the copy constructor note, because the following, for example, does link: class Car { public: Car() { Accelerate(); } void Accelerate(); }; I am not a C++ standards guru but this doesn't seem correct to me. Surely the compiler still should not have had to even generate any code that calls the Car copy constructor. Can anyone confirm if this behaviour is correct? It's been a while since I used C++ - but I don't think this used to be an issue with Visual Studio 6.0 for example. Can anyone suggest a workaround that allows one to "re-use" the Accelerate method from within the copy constructor and still have the copy constructor declared inline?

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• Spring constructor injection error

  - by Jeune

  I am getting the following error for a bean in my application context: Related cause: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'businessLogicContext' d efined in class path resource [activemq-jms-consumer.xml]: Unsatisfied dependency expressed through constructor argument with index 0 of type [java.lang.String]: Could not convert constructor argument value of type [java.util.ArrayList] to required type [java.lang.String]: Failed to convert value of type [java.util.ArrayList] to required type [java.lang.Stri ng]; nested exception is java.lang.IllegalArgumentException: Cannot convert value of type [java.util.ArrayList] to requi red type [java.lang.String]: no matching editors or conversion strategy found at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:53 4) at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:18 6) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAuto wireCapableBeanFactory.java:855) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutow ireCapableBeanFactory.java:765) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCap ableBeanFactory.java:412) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory$1.run(AbstractAutowireCapableBea nFactory.java:383) at java.security.AccessController.doPrivileged(Native Method) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapab leBeanFactory.java:353) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:245) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegis try.java:169) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:242) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:164) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListable BeanFactory.java:400) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplic ationContext.java:736) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:369) at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java :123) at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java :66) Here is my bean: <bean id="businessLogicContext" class="org.springframework.context.support.ClassPathXmlApplicationContext" depends-on="resolveProperty"> <constructor-arg index="0"> <list> <value>jms-applicationContext.xml</value> <value>jms-managerBeanContext.xml</value> <value>jms-daoContext.xml</value> <value>jms-serviceContext.xml</value> </list> </constructor-arg> </bean> I don't know what's wrong, I have googled how to inject a string array via constructor injection and the way I do it above seems okay.

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• Inheriting from ViewPage forces explicit casting of model in view

  - by Martin Hansen

  I try to inhering from ViewPage as shown in this question http://stackoverflow.com/questions/370500/inheriting-from-viewpage But I get a Compiler Error Message: CS1061: 'object' does not contain a definition for 'Spot' and no extension method 'Spot' accepting a first argument of type 'object' could be found (are you missing a using directive or an assembly reference?) My viewpage, normally I can do Model.ChildProperty(Spot) when I inherit from ViewPage directly, so I do that here too. But it fails. <%@ Page Language="C#" Inherits="Company.Site.ViewPageBase<WebSite.Models.SpotEntity>" %> <h1><%= Html.Encode(Model.Spot.Title) %></h1> To get it working correctly I have to do like this: <%@ Page Language="C#" Inherits="Company.Site.ViewPageBase<WebSite.Models.SpotEntity>" %> <h1><%= Html.Encode(((WebSite.Models.SpotEntity)Model).Spot.Title) %></h1> Here is my classes: namespace Company.Site { public class ViewPageBase<TModel> : Company.Site.ViewPageBase where TModel:class { private ViewDataDictionary<TModel> _viewData; [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")] public new ViewDataDictionary<TModel> ViewData { get { if (_viewData == null) { SetViewData(new ViewDataDictionary<TModel>()); } return _viewData; } set { SetViewData(value); } } protected override void SetViewData(ViewDataDictionary viewData) { _viewData = new ViewDataDictionary<TModel>(viewData); base.SetViewData(_viewData); } } public class ViewPageBase : System.Web.Mvc.ViewPage { } } So how do I get it to work without the explicit cast?

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• C++: Explicit DLL Loading: First-chance Exception on non "extern C" functions

  - by Shiftbit

  I am having trouble importing my C++ functions. If I declare them as C functions I can successfully import them. When explicit loading, if any of the functions are missing the extern as C decoration I get a the following exception: First-chance exception at 0x00000000 in cpp.exe: 0xC0000005: Access violation. DLL.h: extern "C" __declspec(dllimport) int addC(int a, int b); __declspec(dllimport) int addCpp(int a, int b); DLL.cpp: #include "DLL.h" int addC(int a, int b) { return a + b; } int addCpp(int a, int b) { return a + b; } main.cpp: #include "..DLL/DLL.h" #include <stdio.h> #include <windows.h> int main() { int a = 2; int b = 1; typedef int (*PFNaddC)(int,int); typedef int (*PFNaddCpp)(int,int); HMODULE hDLL = LoadLibrary(TEXT("../Debug/DLL.dll")); if (hDLL != NULL) { PFNaddC pfnAddC = (PFNaddC)GetProcAddress(hDLL, "addC"); PFNaddCpp pfnAddCpp = (PFNaddCpp)GetProcAddress(hDLL, "addCpp"); printf("a=%d, b=%d\n", a,b); printf("pfnAddC: %d\n", pfnAddC(a,b)); printf("pfnAddCpp: %d\n", pfnAddCpp(a,b)); //EXCEPTION ON THIS LINE } getchar(); return 0; } How can I import c++ functions for dynamic loading? I have found that the following code works with implicit loading by referencing the *.lib, but I would like to learn about dynamic loading. Thank you to all in advance.

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• Explicit script end tag always converted to self-closing

  - by Jonas

  I'm using xslt to transform xml to an aspx file. In the xslt, I have a script tag to include a jquery.js file. To get it to work with IE, the script tag must have an explicit closing tag. For some reason, this doesn't work with xslt below. <?xml version="1.0" encoding="utf-8"?> <xsl:stylesheet version="1.0" xmlns="http://www.w3.org/1999/xhtml" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxsl="urn:schemas-microsoft-com:xslt" exclude-result-prefixes="msxsl" xmlns:asp="remove"> <xsl:output method="html"/> <xsl:template match="/"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>TEST</title> <script type="text/javascript" src="jquery-1.2.6.js"></script> But if I change the script tag as shown below, it works. <script type="text/javascript" src="jquery-1.2.6.js"> // <![CDATA[ // ]]> </script> I thought that the <xsl:output method="html" /> would do the trick, but it doesn't seem to work? /Jonas

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• Explicit localization problem

  - by X-Dev

  when trying to translate the confirmation message to Norwegian i get the following error: Cannot have more than one binding on property 'OnClientClick' on 'System.Web.UI.WebControls.LinkButton'. Ensure that this property is not bound through an implicit expression, for example, using meta:resourcekey. i use Explicit localization in the following manner: <asp:LinkButton ID="lnkMarkInvoiced" runat="server" OnClick="lnkMarkInvoiced_OnClick" OnClientClick="<%# Resources: lnkMarkInvoicedResource.OnClientClick%>" Visible="False" CssClass="stdtext" meta:resourcekey="lnkMarkInvoicedResource" ></asp:LinkButton> here's the local resource file entry: <data name="lnkMarkInvoicedResource.OnClientClick" xml:space="preserve"> <value>return confirm('Er du sikker?');</value> if i remove the meta attribute i get the English text(default). how do i get the Norwegian text appearing without resorting to using the code behind? Update: removing the meta attribute prevents the exception from occurring but the original problem still exists. I can't get the Norwegian text to show. only the default English text shows. Another Update: I know this question is getting old but i still can't get the Norwegian text to display. If anyone has some tips please post a response.

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• C++ explicit template specialization of templated constructor of templated class

  - by Victor Liu

  I have a class like template <class T> struct A{ template <class U> A(U u); }; I would like to write an explicit specialization of this for a declaration like A<int>::A(float); In the following test code, if I comment out the specialization, it compiles with g++. Otherwise, it says I have the wrong number of template parameters: #include <iostream> template <class T> struct A{ template <class U> A(T t, U *u){ *u += U(t); } }; template <> template <> A<int>::A<int,float>(int t, float *u){ *u += U(2*t); } int main(){ float f = 0; int i = 1; A<int>(i, &f); std::cout << f << std::endl; return 0; }

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• Linq-to-XML explicit casting in a generic method

  - by vlad

  I've looked for a similar question, but the only one that was close didn't help me in the end. I have an XML file that looks like this: <Fields> <Field name="abc" value="2011-01-01" /> <Field name="xyz" value="" /> <Field name="tuv" value="123.456" /> </Fields> I'm trying to use Linq-to-XML to get the values from these fields. The values can be of type Decimal, DateTime, String and Int32. I was able to get the fields one by one using a relatively simple query. For example, I'm getting the 'value' from the field with the name 'abc' using the following: private DateTime GetValueFromAttribute(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == "abc" select (DateTime)field.Attribute("value")).FirstOrDefault() } this is placed in a separate function that simply returns this value, and everything works fine (since I know that there is only one element with the name attribute set to 'abc'). however, since I have to do this for decimals and integers and dates, I was wondering if I can make a generic function that works in all cases. this is where I got stuck. here's what I have so far: private T GetValueFromAttribute<T>(IEnumerable<XElement> fields, String attName) { return (from field in fields where field.Attribute("name").Value == attName select (T)field.Attribute("value").Value).FirstOrDefault(); } this doesn't compile because it doesn't know how to convert from String to T. I tried boxing and unboxing (i.e. select (T) (Object) field.Attribute("value").Value but that throws a runtime Specified cast is not valid exception as it's trying to convert the String to a DateTime, for instance. Is this possible in a generic function? can I put a constraint on the generic function to make it work? or do I have to have separate functions to take advantage of Linq-to-XML's explicit cast operators?

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• Android Custom View Constructor

  - by Mitch

  I'm learning about using Custom Views from the following: http://developer.android.com/guide/topics/ui/custom-components.html#modifying The description says: Class Initialization As always, the super is called first. Furthermore, this is not a default constructor, but a parameterized one. The EditText is created with these parameters when it is inflated from an XML layout file, thus, our constructor needs to both take them and pass them to the superclass constructor as well. Is there a better description? I've been trying to figure out what the constructor(s) should look like and I've come up with 4 possible choices (see example at end of post). I'm not sure what these 4 choices do (or don't do), why I should implement them, or what the parameters mean. Is there a description of these? Thanks. Mitch public MyCustomView() { super(); } public MyCustomView(Context context) { super(context); } public MyCustomView(Context context, AttributeSet attrs) { super(context, attrs); } public MyCustomView(Context context, AttributeSet attrs, Map params) { super(context, attrs, params); }

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• Boost Python : How to only expose the constructor of a class with virtual (pure & impure) methods

  - by fallino

  Hello, I'm a newbie with Boost::Python but I tried to search on the web to do so I want to expose a 3rd party library to Python. One of the class of the library (.hpp) is composed of a public constructor with arguments a protected constructor and functions various regular functions various pure virtual functions various non pure virtual functions First, I did not succeed in building it without having errors about this protected constructor. I finally commented it. A first question would be : Is there a way to exclude these protected functions since I don't want to expose them ? (I know it's possible and easy with Py++, but I started without using it) Then I tried to expose all of my functions, beginning with the pure virtual ones (commenting them all except one), which wasn't a success too So I finally decided not to expose these virtual functions (which in fact seems logical...), but, here again, I didn't manage building it with a simple constructor with arguments (without no_init). So my second question is : Is there a way to exclude these virtual functions since I don't want to expose them ? Sorry if it seems trivial but I didn't find anything explicit on the web and I need something rather explicit :). Thanks in advance

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• Swig: No Constructor defined

  - by wheaties

  I added %allowexcept to my *.i file when building a Python <-- C++ bridge using Swig. Then I removed that preprocessing directive. Now I can't get the Python produced code to recognize the constructor of a C++ class. Here's the class file: #include <exception> class Swig_Foo{ public: Swig_Foo(){} virtual ~Swig_Foo(){} virtual getInt() =0; virtual throwException() { throw std::exception(); } }; And here's the code Swig produces from it: class Swig_Foo: __swig_setmethods__ = {} __setattr__ = lambda self, name, value: _swig_setattr(self, Swig_Foo, name, value) __swig_getmethods__ = {} __getattr__ = lambda self, name: _swig_getattr(self, Swig_Foo, name) def __init__(self): raise AttributeError, "No constructor defined" __repr__ = _swig_repr __swig_destroy__ = _foo.delete_Swig_Foo __del__ = lambda self : None; def getInt(*args): return apply(_foo.Swig_Foo_getInt, args) def throwOut(*args): return apply(_foo.Swig_Foo_throwOut, args) Swig_Foo_swigregister = _foo.Swig_Foo_swigregister Swig_Foo_swigregister(Swig_Foo) The problem is the def __init__self): raise AttributeError, "No constructor defined" portion. It never did this before I added the %allowexception and now that I've removed it, I can't get it to create a real constructor. All the other classes have actual constructors. Quite baffled. Anyone know how I can get it to stop doing this?

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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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• Dependency Properties, change notification and setting values in the constructor

  - by stefan.at.wpf

  Hello, I have a clas with 3 dependency properties A,B,C. The values of these properties are set by the constructor and every time one of the properties A, B or C changes, the method recalculate() is called. Now during execution of the constructor these method is called 3 times, because the 3 properties A, B, C are changed. Hoewever this isn't necessary as the method recalculate() can't do anything really useful without all 3 properties set. So what's the best way for property change notification but circumventing this change notification in the constructor? I thought about adding the property changed notification in the constructor, but then each object of the DPChangeSample class would always add more and more change notifications. Thanks for any hint! class DPChangeSample : DependencyObject { public static DependencyProperty AProperty = DependencyProperty.Register("A", typeof(int), typeof(DPChangeSample), new PropertyMetadata(propertyChanged)); public static DependencyProperty BProperty = DependencyProperty.Register("B", typeof(int), typeof(DPChangeSample), new PropertyMetadata(propertyChanged)); public static DependencyProperty CProperty = DependencyProperty.Register("C", typeof(int), typeof(DPChangeSample), new PropertyMetadata(propertyChanged)); private static void propertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { ((DPChangeSample)d).recalculate(); } private void recalculate() { // Using A, B, C do some cpu intensive caluclations } public DPChangeSample(int a, int b, int c) { SetValue(AProperty, a); SetValue(BProperty, b); SetValue(CProperty, c); } }

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• Attaching methods to prototype from within constructor function

  - by Matthew Taylor

  Here is the textbook standard way of describing a 'class' or constructor function in JavaScript, straight from the Definitive Guide to JavaScript: function Rectangle(w,h) { this.width = w; this.height = h; } Rectangle.prototype.area = function() { return this.width * this.height; }; I don't like the dangling prototype manipulation here, so I was trying to think of a way to encapsulate the function definition for area inside the constructor. I came up with this, which I did not expect to work: function Rectangle(w,h) { this.width = w; this.height = h; this.constructor.prototype.area = function() { return this.width * this.height; }; } I didn't expect this to work because the this reference inside the area function should be pointing to the area function itself, so I wouldn't have access to width and height from this. But it turns out I do! var rect = new Rectangle(2,3); var area = rect.area(); // great scott! it is 6 Some further testing confirmed that the this reference inside the area function actually was a reference to the object under construction, not the area function itself. function Rectangle(w,h) { this.width = w; this.height = h; var me = this; this.constructor.prototype.whatever = function() { if (this === me) { alert ('this is not what you think');} }; } Turns out the alert pops up, and this is exactly the object under construction. So what is going on here? Why is this not the this I expect it to be?

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• Constructor and Destructors in C++ work?

  - 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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• Calling a constructor from method within the same class

  - by Nathan

  I'm new to java and I'm learning about creating object classes. One of my homework assignment requires that I call the constructor at least once within a method of the same object class. I'm getting an error that says The method DoubleMatrix(double[][]) is undefined for the type DoubleMatrix Here's my constructor: public DoubleMatrix(double[][] tempArray) { // Declaration int flag = 0; int cnt; // Statement // check to see if doubArray isn't null and has more than 0 rows if(tempArray == null || tempArray.length < 0) { flag++; } // check to see if each row has the same length if(flag == 0) { for(cnt = 0; cnt <= tempArray.length - 1 || flag != 1; cnt++) { if(tempArray[cnt + 1].length != tempArray[0].length) { flag++; } } } else if(flag == 1) { makeDoubMatrix(1, 1);// call makeDoubMatrix method } }// end constructor 2 Here's the method where I try and call the constructor: public double[][] addMatrix(double[][] tempDoub) { // Declaration double[][] newMatrix; int rCnt, cCnt; //Statement // checking to see if both are of same dimension if(doubMatrix.length == tempDoub.length && doubMatrix[0].length == tempDoub[0].length) { newMatrix = new double[doubMatrix.length][doubMatrix[0].length]; // for loop to add matrix to a new one for(rCnt = 0; rCnt <= doubMatrix.length; rCnt++) { for(cCnt = 0; cCnt <= doubMatrix.length; cCnt++) { newMatrix[rCnt][cCnt] = doubMatrix[rCnt][cCnt] + tempDoub[rCnt][cCnt]; } } } else { newMatrix = new double[0][0]; DoubleMatrix(newMatrix) } return newMatrix; }// end addMatrix method Can someone point me to the right direction and explain why I'm getting an error?

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• How to remove the explicit dependencies to other projects' libraries in Eclipse launch configuration

  - by euluis

  In Eclipse it is possible to create launch configurations in a project, specifying the runtime dependencies from another project. A problem I found was that if you have a multiple project workspace, being possible that each project has its own libraries, it is easy to add explicit dependencies in a secondary project to libraries that are of another project and therefore subject to change. An example of this problem follows: proj1 +-- src +-- lib +-- jar1-v1.0.jar +-- jar2-v1.0.jar proj2 +-- src +-- proj2-tests.launch I don't have a dependency from the code in proj2/src to the libraries in proj1/lib. Nevertheless, I do have a dependency from proj2/src to proj1/src, although since there is an internal dependency in the code in proj1/src to its libraries jar1-v1.0.jar and jar2.v1.0.jar, I have to add a dependency in proj2-tests.launch to the libraries in proj1/lib. This translates to the following ugly lines in proj2-tests.launch: <listEntry value="<?xml version="1.0" encoding="UTF-8" standalone="no"?> <runtimeClasspathEntry path="3" projectName="proj1" type="1"/> "/> <listEntry value="<?xml version="1.0" encoding="UTF-8" standalone="no"?> <runtimeClasspathEntry internalArchive="/proj1/lib/jar1-v1.0.jar" path="3" type="2"/> "/> <listEntry value="<?xml version="1.0" encoding="UTF-8" standalone="no"?> <runtimeClasspathEntry internalArchive="/proj1/lib/jar2-v1.0.jar" path="3" type="2"/> "/> This wouldn't be a big problem if there wasn't the need from time to time to evolve the software, upgrade the libraries and etc. Consider the common need to upgrade the libraries jar1-v1.0.jar and jar2-v1.0.jar to their versions v1.1. Consider that you have about 10 projects in one workspace, having about 5 libraries each and about 4 launch configurations. You get a maintenance overhead in doing a simple upgrade of a library, which normally must imply changes in files for which there wasn't the need for. Or maybe I'm doing something wrong... What I would like to state is proj2 depends on proj1 and on its libraries and having this translated to simply that in the *.launch files. Is that possible?

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• Avoiding explicit recursion in Haskell

  - by Travis Brown

  The following simple function applies a given monadic function iteratively until it hits a Nothing, at which point it returns the last non-Nothing value. It does what I need, and I understand how it works. lastJustM :: (Monad m) => (a -> m (Maybe a)) -> a -> m a lastJustM g x = g x >>= maybe (return x) (lastJustM g) As part of my self-education in Haskell I'm trying to avoid explicit recursion (or at least understand how to) whenever I can. It seems like there should be a simple non-explicitly recursive solution in this case, but I'm having trouble figuring it out. I don't want something like a monadic version of takeWhile, since it could be expensive to collect all the pre-Nothing values, and I don't care about them anyway. I checked Hoogle for the signature and nothing shows up. The m (Maybe a) bit makes me think a monad transformer might be useful here, but I don't really have the intuitions I'd need to come up with the details (yet). It's probably either embarrassingly easy to do this or embarrassingly easy to see why it can't or shouldn't be done, but this wouldn't be the first time I've used self-embarrassment as a pedagogical strategy. Background: Here's a simplified working example for context: suppose we're interested in random walks in the unit square, but we only care about points of exit. We have the following step function: randomStep :: (Floating a, Ord a, Random a) => a -> (a, a) -> State StdGen (Maybe (a, a)) randomStep s (x, y) = do (a, gen') <- randomR (0, 2 * pi) <$> get put gen' let (x', y') = (x + s * cos a, y + s * sin a) if x' < 0 || x' > 1 || y' < 0 || y' > 1 then return Nothing else return $ Just (x', y') Something like evalState (lastJustM (randomStep 0.01) (0.5, 0.5)) <$> newStdGen will give us a new data point.

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• c# copy constructor generator

  - by Shawn Mclean

  I want to copy values from one object to another object. Something similiar to pass by value but with assignment. Eg. PushPin newValPushPin = oldPushPin; //I want to break the reference here. I was told to write a copy constructor for this. But this class has alot of properties, it will probably take an hour to write a copy constructor by hand. Is there a better way to assign an object to another object by value? If not, is there a copy constructor generator?

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• Constructor in a Interface?

  - by Sebi

  I know its not possible to define a constructor in a interface. But im wondering why, because i think i could be very useful. So you could be sure that some fields in a class are defined for every implementaiton of this interface. For example consider the following message class: public class MyMessage { public MyMessage(String receiver) { this.receiver = receiver; } private String receiver; public void send() { //some implementation for sending the mssage to the receiver } } If a define a Interface for this class so that i can have more classes which implement the message interface, i can only define the send method and not the constructor. So how can i assure that every implementation of this class really has an receiver setted? If i use a method like setReceiver(String receiver) i can't be sure that this method is really called. In the constructor i could assure it.

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