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  • Checking lazy loaded properties have been instantiated

    - by PaulG
    In a class which has a lazy loaded property, such as: private Collection<int> someInts; public Collection<int> SomeInts { get { if (this.someInts == null) this.someInts = new Collection<int>(); return this.someInts; } } Is it worth also having a property such as: public bool SomeIntsExist { get { return (this.someInts != null && this.someInts.Count > 0); } } And then using that property.. eg: if (thatClass.SomeIntsExist) { // do something with thatClass.SomeInts collection } or is this premature optimisation. Its certainly easier to roll with something like below, but it will instantiate the collection needlessly: if (thatClass.SomeInts.Count > 0) { // do something with thatClass.SomeInts collection } Is the compiler smart enough to figure things like this out? Is there a better way?

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  • Limit scope of #define

    - by Ujjwal Singh
    What is the correct strategy to limit the scope of #define and avoid unwarrented token collisions. In the following configuration: Main.c # include "Utility_1.h" # include "Utility_2.h" VOID Utility() // Was written without knowing of: Utility_1 & Utility_2 { const UINT ZERO = 0; } VOID Main() { ... } // Collision; for Line:5 Compiler does not indicate what replaced Utility_1.h # define ZERO "Zero" # define ONE "One" BOOL Utility_1(); Utility_2.h # define ZERO '0' # define ONE '1' BOOL Utility_2(); Utility_2.c # include "Utility_2.h" BOOL Utility_2() { // Using: ZERO & ONE } //Collision: Character Literal replaced with String {Edit} Note: This is supposed to be a generic quesition so do not limit yourself to enum or other defined types. i.e. What to do when: I MUST USE #define Please comment on my proposed solution below.. _

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  • C++/CLI value class constraint won't compile. Why?

    - by Simon
    Hello, a few weeks ago a co-worker of mine spent about two hours finding out why this piece of C++/CLI code won't compile with Visual Studio 2008 (I just tested it with Visual Studio 2010... same story). public ref class Test { generic<class T> where T : value class void MyMethod(Nullable<T> nullable) { } }; The compiler says: Error 1 error C3214: 'T' : invalid type argument for generic parameter 'T' of generic 'System::Nullable', does not meet constraint 'System::ValueType ^' C:\Users\Simon\Desktop\Projektdokumentation\GridLayoutPanel\Generics\Generics.cpp 11 1 Generics Adding ValueType will make the code compile. public ref class Test { generic<class T> where T : value class, ValueType void MyMethod(Nullable<T> nullable) { } }; My question is now. Why? What is the difference between value class and ValueType?

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  • Beginner assembly programming memory usage question

    - by Daniel
    I've been getting into some assembly lately and its fun as it challenges everything i have learned. I was wondering if i could ask a few questions When running an executable, does the entire executable get loaded into memory? From a bit of fiddling i've found that constants aren't really constants? Is it just a compiler thing? const int i = 5; _asm { mov i, 0 } // i is now 0 and compiles fine So are all variables assigned with a constant value embedded into the file as well? Meaning: int a = 1; const int b = 2; void something() { const int c = 3; int d = 4; } Will i find all of these variables embedded in the file (in a hex editor or something)? If the executable is loaded into memory then "constants" are technically using memory? I've read around on the net people saying that constants don't use memory, is this true?

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  • "Inherited" types in C++

    - by Ken Moynihan
    The following code does not compile. I get an error message: error C2039: 'Asub' : is not a member of 'C' Can someone help me to understand this? Tried VS2008 & 2010 compiler. template <class T> class B { typedef int Asub; public: void DoSomething(typename T::Asub it) { } }; class C : public B<C> { public: typedef int Asub; }; class A { public: typedef int Asub; }; int _tmain(int argc, _TCHAR* argv[]) { C theThing; theThing.DoSomething(C::Asub()); return 0; }

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  • Why do Java source files go into a directory structure?

    - by bdhar
    Suppose that I am creating a Java project with the following classes com.bharani.ClassOne com.bharani.ClassTwo com.bharani.helper.HelperOne com.bharani.helper.support.HelperTwo with files put immediately under the folder 'src' src/ClassOne.java src/ClassTwo.java src/HelperOne.java src/HelperTwo.java and compile them using the command $ javac src/*.java -d classes (assuming that classes directory exists) The compiler compiles these files and put the class files in appropriate sub-directories inside the 'classes' directory like this classes/com/bharani/ClassOne.class classes/com/bharani/ClassTwo.class classes/com/bharani/helper/HelperOne.class classes/com/bharani/helper/support/HelperTwo.class Because the spec mandates that the classes should go inside appropriate directory structure. Fine. My question is this: When I use an IDE such as Eclipse or NetBeans, they create the directory structure for the source code directory ('src' directory here) also. Why is that? Is it mandatory? Or, is it just a convention? Thanks.

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  • Why am I getting this warning about my app delegate and CLLocationManageDelegate?

    - by Dan Ray
    Observe this perfectly simple UIViewController subclass method: -(IBAction)launchSearch { OffersSearchController *search = [[OffersSearchController alloc] initWithNibName:@"OffersSearchView" bundle:nil]; EverWondrAppDelegate *del = [UIApplication sharedApplication].delegate; [del.navigationController pushViewController:search animated:YES]; [search release]; } On the line where I get *del, I am getting a compiler warning that reads, Type 'id <UIApplicationDelegate>' does not conform to the 'CLLocationManagerDelegate' protocol. In fact, my app delegate DOES conform to that protocol, AND what I'm doing here has nothing at all to do with that. So what's up with that message? Secondary question: sometimes I can get to my navigationController via self.navigationController, and sometimes I can't, and have to go to my app delegate's property to get it like I'm doing here. Any hint about why that is would be very useful.

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  • Passing a template func. as a func. ptr to an overloaded func. - is there a way to compile this code

    - by LoudNPossiblyRight
    Just a general c++ curiosity: This code below shouldn't compile because it's impossible to know which to instantiate: temp(const int&) or temp(const string&) when calling func(temp) - this part i know. What i would like to know is if there is anything i can do to the line marked PASSINGLINE to get the compiler to deduce that i want FPTR1 called and not FPTR2 ? #include<iostream> using std::cout; using std::endl; /*FPTR1*/ void func(void(*fptr)(const int&)){ fptr(1001001);} /*FPTR2*/ void func(void(*fptr)(const string&)){ fptr("1001001"); } template <typename T> void temp(const T &t){ cout << t << endl; } int main(){ /*PASSINGLINE*/ func(temp); return 0; } Thank you.

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  • Has anyone been successful at a assembler based led blinker for an xcore?

    - by dwelch
    I am liking the http://www.xmos.com chips but want to get a lower level understanding of what is going on. Basically assembler. I am trying to sort out something as simple as an led blinker, set the led, count to N clear the led, count to N, loop forever. Sure I can disassemble a 10 line XC program, but if you have tried that you will see there is a lot of bloat in there that is in every program, what bits are to support the compiler output and what bits are actually setting up the gpio?

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  • C# extern int ? How do I make a global var across classes and namespaces ?

    - by dr d b karron
    Dear C#'ers; As an old C/C++ programmer, I want to keep a global int counter across all of MY namespaces and classes. Public static extern int EventCount; Is not working; the VS2010 compiler won't let me have an extern int. Even with a DLLImport. [DllImport ( "SilverlightApplication37.dll" )] public static extern int EventCount; VS2010 complains Error 1 The modifier 'extern' is not valid for this item so how do i have a global int across all my code ? Cheers! dr.K

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  • Eclipse RCP standalone export problem with Groovy scripts

    - by geejay
    I am trying to export a standalone RCP app using Eclipse 3.5.2. The app has a main pure Java plug-in, and a Java / Groovy plug-in that is used by the main plug-in. When I export the main RCP plug-in using the "Export Wizard", I get compiler errors saying that the Groovy classes cannot be found, e.g ERROR in C:\mysrc\src\ch\calcs\providers\CalcProvider.java (at line 8) import ch.calcs.ArgSet; This plug-in works fine when run from within Eclipse. Any ideas?

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  • Disallow private constructor invocation in friend function

    - by user2907032
    Is there any way to not allow private construction in friend function, In case we do have private constructor with friend function in our class. Only Static method should be responsible for object creation and other than this compiler should flash error message #include <iostream> #include <memory> using namespace std; class a { public: void see () { cout<<"Motimaa"; } static a& getinstance() { static a instance; return instance; } private: a() {}; friend void access(); }; void access () { a obj; obj.see();//still friend function can access } int main() { a::getinstance().see(); access(); return 1; }

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  • Why won't the debugger update?

    - by Tanner
    Hello everyone, Ive had this problem multiple times and it ruins my projects, I make some changes, like say I have a button in the top left corner of the form and move it to the top right corner, then I press debug but nothing happens to the form, it doesn't change the button is still in the top left-hand corner instead of the top right, and it also doesn't except any new code, its like it saved the project right there and won't move on. Does any one know why or had this problem before? Please, Help!!!! Additional Details: Compiler: Microsoft Visual C# 2008 Express Edition I once fixed this problem by rebuilding the solution, but its never worked again.

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  • Change default Console I/O functions handle.

    - by b-gen-jack-o-neill
    Hello. Is it possible to somehow change standart I/O functions handle on Windows? Language preffered is C++. If I understand it right, by selecting console project, compiler just pre-allocate console for you, and operates all standart I/O functions to work with its handle. So, what I want to do is to let one Console app actually write into another app Console buffer. I though that I could get first´s Console handle, than pass it to second app by a file (I don´t know much about interprocess comunication, and this seems easy) and than somehow use for example prinf with the first app handle. Can this be done? I know how to get console handle, but I have no idea how to redirect printf to that handle. Its just study-purpose project to more understand of OS work behind this. I am interested in how printf knows what Console it is assiciated with.

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  • how VAR is determined against many options?

    - by Royi Namir
    i have this code : IEnumerable<string> q = customers /*EF entity*/ .Select (c => c.Name.ToUpper()) .OrderBy (n => n) To select entity, ObjectContext actually create ObjectQuery, which implement IQueryable. The object return from ObjectQuery, is not normal object, but EntityObject but what if i write : ( notice the var) var q = customers /*EF entity*/ .Select (c => c.Name.ToUpper()) .OrderBy (n => n) it can be determined both to ienumerable or iqueryable : because ObjectQuery Also implements IEnumerable... i dont know if there's any specific info which tell the compiler "use A and not B. A is more specific..." ( there must be...i just cant find it) any help ? how will it know to use A || B ?

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  • Scala: Mixing traits with private fields

    - by Vilius Normantas
    It's not much of a question, it's rather my excitement that it's possible at all! I wrote this little example just to prove the opposite - I expected either a compiler error or one of the values (111 or 222, I wasn't sure). scala> trait T1 { private val v = 111; def getValueT1 = v } scala> trait T2 { private val v = 222; def getValueT2 = v } scala> class T12 extends T1 with T2 scala> val t = new T12 scala> t.getValueT1 res9: Int = 111 scala> t.getValueT2 res10: Int = 222 Why doesn't the v get overridden? Off course this works only as long as vs are private, but still.

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  • xml to xsd to c# class - C# 3.0, .net 3.5

    - by uno
    Following this articlelink text one of the comments from 'zanoni' said he did it this way Using .NET 3.5: [XmlRoot] public class EmailConfiguration { [XmlElement] public string DataBoxID { get; set; } [XmlElement] public DefaultSendToAddressCollectionClass DefaultSendToAddressCollection { get; set; } } public class DefaultSendToAddressCollectionClass { [XmlElement] public string[] EmailAddress { get; set; } } How would I get my class to be as what he described? I ran the xsd tool and it is in the fashion as what shane posted in the above link [System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.3038")] [System.SerializableAttribute()] [System.Diagnostics.DebuggerStepThroughAttribute()] [System.ComponentModel.DesignerCategoryAttribute("code")] [System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true)] [System.Xml.Serialization.XmlRootAttribute(Namespace="", IsNullable=false)] public partial class EmailConfiguration : object, System.ComponentModel.INotifyPropertyChanged { private string dataBoxIDField; private EmailConfigurationDefaultSendToAddressCollection[] defaultSendToAddressCollectionField; /// <remarks/> [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified)] public string DataBoxID { get { return this.dataBoxIDField; } set { this.dataBoxIDField = value; this.RaisePropertyChanged("DataBoxID"); } }

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  • "_FILE_AND_LINE_ is not defined in this scope" (compiling RakNet NAT examples in OS X)

    - by Michael F
    Hello! I'm working on a RakNet-based project (using 3.8 on OS X 10.6), and I'm trying to work through the various examples that demonstrate the parts of RakNet I want to use. For the "NatCompleteClient" example, I've imported the source into a command-line project in XCode, along with the UPNP dependency. At compile time I've had a few errors in the UPNP section, though, and I can't find any guidance on this. In UPNPPortForwarder.mm, there are 7 lines that use _FILE_AND_LINE_, and the compiler is not happy; for example on line 232: foundInterfaces.Deallocate(r1,_FILE_AND_LINE_); causes: UPNPPortForwarder.mm:232: error: '_FILE_AND_LINE_' was not declared in this scope Can anyone tell me what this is all about? That variable doesn't seem to get talked about very often... or Google doesn't like to find it.

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  • What's a good way to write XML in C++?

    - by nebukadnezzar
    There are plenty of Libraries to parse XML, but it seems there aren't many good (?) ways to write XML in C++. Libraries I've been using so far: PugiXML: really lightweight, very straightforwarded API, but it seems to lack a way to write XML (Or I haven't found it yet) RapidXML: I don't have much experience with RapidXML; But it does look nice. TinyXML: I find it odd that the STL TinyXML needs to be explicitly "enabled" in TinyXML - I mean, if your compiler doesn't support the STL, get a better one! Anyway, to make my point clear, I have written a PHP Script that does what I plan to do in C++: http://codepad.org/RyhQSgcm I really appreciate any help!

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  • C#: Why only integral enums?

    - by JamesBrownIsDead
    I've been writing C# for seven years now, and I keep wondering, why do enums have to be of an integral type? Wouldn't it be nice to do something like: enum ErrorMessage { NotFound: "Could not find", BadRequest: "Malformed request" } Is this a language design choice, or are there fundamental incompatibilities on a compiler, CLR, or IL level? Do other languages have enums with string or complex (i.e. object) types? What languages? (I'm aware of workarounds; my question is, why are they needed?) EDIT: "workarounds" = attributes or static classes with consts :)

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  • Core Data produces Analyzer warnings

    - by RickiG
    Hi I am doing the final touch ups on an app and I am getting rid of every compiler/analyzer warning. I have a bunch of Class methods that wrap my apps access to Core Data entities. This is "provoking" the analyzer. + (CDProductEntity*) newProductEntity { return (CDProductEntity*)[NSEntityDescription insertNewObjectForEntityForName:@"CDProductEntity" inManagedObjectContext:[self context]]; } Which results in an Analyzer warning: Object with +0 retain counts returned to caller where a +1 (owning) retain count is expected In the method that calls the above Class Method I have this: CDProductEntity *newEntity = [self newProductEntity]; Which results in an Analyzer warning: Method returns an Objective-C object with a +1 retain count (owning reference) Explicitly releasing or autoreleasing a Core Data entity is usually very very bad, but is that what it is asking me to do here? First it tells me it has a +0 retain count and that is bad, then it tells me it has a +1 which is also bad. What can I do to ensure that I am either dealing with a Analyzer hiccup or that I release correctly? Thanks in advance

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  • How we run a .NET 32-bit application in a 64-bit Windows server?

    - by Geo
    We are installing a third party application in one of our 64-bit Windows servers. This application apparently was build with the compiler option set to choose the platform at run time. When we run the application it gives us an error: System.BadImageFormatException: is not a valid Win32 application. I have seen in MSDN forums that in order to fix this error I have to build the application set to 32-bit, and that way it will run fine on a 64-bit server. I check on other StackOverflow links Other Posts. How to get around this situation? For everyone that wants to know more information: The application is running fine in a 32-bit test server. IIS version 6 using SQL Server Express 2005 On the Web Service Extension there are both Framework64\v2.0.50727\aspnet_isapi.dll and Framework\v2.0.50727\aspnet_isapi.dll

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  • Netbeans C++ not finding standard libraries (Macintosh)

    - by Grue
    Hello everyone! I am trying to use Netbeans 6.7 (on a Mac) to create C++ applications. I started out with the standard "Hello World," just to test if everything was working correctly. First try std and could not be found. So I tried reinstalling the developer tools on my Mac OS X disk. After that Netbeans updated its c++ compiler info, but still cannot find std or . Odder than this XCode seems to be working with C++ perfectly fine. Any help fixing this would be greatly appreciated.

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  • How to free memory in try-catch blocks?

    - by Kra
    Hi, I have a simple question hopefully - how does one free memory which was allocated in the try block when the exception occurs? Consider the following code: try { char *heap = new char [50]; //let exception occur here delete[] heap; } catch (...) { cout << "Error, leaving function now"; //delete[] heap; doesn't work of course, heap is unknown to compiler return 1; } How can I free memory after the heap was allocated and exception occurred before calling delete[] heap? Is there a rule not to allocate memory on heap in these try .. catch blocks? Thanks

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