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  • Casting to specify unknown object type?

    - by fuzzygoat
    In the following code I have a view object that is an instance of UIScrollView, if I run the code below I get warnings saying that "UIView might not respond to -setContentSize etc." UIImage *image = [UIImage imageNamed:@"Snowy_UK.jpg"]; imageView = [[UIImageView alloc] initWithImage:image]; [[self view] addSubview:imageView]; [[self view] setContentSize:[image size]]; [[self view] setMaximumZoomScale:2.0]; [[self view] setMinimumZoomScale: [[self view] bounds].size.width / [image size].width]; I have checked the type of the object and [self view] is indeed a UIScrollView. I am guessing that this is just the compiler making a bad guess as to the type and the solution is simply to cast the object to the correct type manually, am I getting this right? UIScrollView *scrollView = (UIScrollView *)[self view]; UIImage *image = [UIImage imageNamed:@"Snowy_UK.jpg"]; imageView = [[UIImageView alloc] initWithImage:image]; [[self view] addSubview:imageView]; [scrollView setContentSize:[image size]]; [scrollView setMaximumZoomScale:2.0]; [scrollView setMinimumZoomScale: [scrollView bounds].size.width / [image size].width]; cheers Gary.

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  • Strange inheritance behaviour in Objective-C

    - by Smikey
    Hi all, I've created a class called SelectableObject like so: #define kNumberKey @"Object" #define kNameKey @"Name" #define kThumbStringKey @"Thumb" #define kMainStringKey @"Main" #import <Foundation/Foundation.h> @interface SelectableObject : NSObject <NSCoding> { int number; NSString *name; NSString *thumbString; NSString *mainString; } @property (nonatomic, assign) int number; @property (nonatomic, retain) NSString *name; @property (nonatomic, retain) NSString *thumbString; @property (nonatomic, retain) NSString *mainString; @end So far so good. And the implementation section conforms to the NSCoding protocol as expected. HOWEVER, when I add a new class which inherits from this class, i.e. #import <Foundation/Foundation.h> #import "SelectableObject.h" @interface Pet : SelectableObject <NSCoding> { } @end I suddenly get the following compiler error in the Selectable object class! SelectableObject.h:16: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'interface' This makes no sense to me. Why is the interface declaration for the SelectableObject class suddenly broken? I also import it in a couple of other classes I've written... Any help would be very much appreciated. Thanks! Michael

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  • Is it possible to defer member initialization to the constructor body?

    - by Kjir
    I have a class with an object as a member which doesn't have a default constructor. I'd like to initialize this member in the constructor, but it seems that in C++ I can't do that. Here is the class: #include <boost/asio.hpp> #include <boost/array.hpp> using boost::asio::ip::udp; template<class T> class udp_sock { public: udp_sock(std::string host, unsigned short port); private: boost::asio::io_service _io_service; udp::socket _sock; boost::array<T,256> _buf; }; template<class T> udp_sock<T>::udp_sock(std::string host = "localhost", unsigned short port = 50000) { udp::resolver res(_io_service); udp::resolver::query query(udp::v4(), host, "spec"); udp::endpoint ep = *res.resolve(query); ep.port(port); _sock(_io_service, ep); } The compiler tells me basically that it can't find a default constructor for udp::socket and by my research I understood that C++ implicitly initializes every member before calling the constructor. Is there any way to do it the way I wanted to do it, or is it too "Java-oriented" and not feasible in C++? I worked around the problem by defining my constructor like this: template<class T> udp_sock<T>::udp_sock(std::string host = "localhost", unsigned short port = 50000) : _sock(_io_service) { udp::resolver res(_io_service); udp::resolver::query query(udp::v4(), host, "spec"); udp::endpoint ep = *res.resolve(query); ep.port(port); _sock.bind(ep); } So my question is more out of curiosity and to better understand OOP in C++

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  • C/C++ Control Structure Limitations?

    - by STingRaySC
    I have heard of a limitation in VC++ (not sure which version) on the number of nested if statements (somewhere in the ballpark of 300). The code was of the form: if (a) ... else if (b) ... else if (c) ... ... I was surprised to find out there is a limit to this sort of thing, and that the limit is so small. I'm not looking for comments about coding practice and why to avoid this sort of thing altogether. Here's a list of things that I'd imagine could have some limitation: Number of functions in a scope (global, class, or namespace). Number of expressions in a single statement (e.g., compound conditionals). Number of cases in a switch. Number of parameters to a function. Number of classes in a single hierarchy (either inheritance or containment). What other control structures/language features have limits such as this? Do the language standards say anything about these limits (perhaps minimum requirements for an implementation)? Has anyone run into a particular language limitation like this with a particular compiler/implementation? EDIT: Please note that the above form of if statements is indeed "nested." It is equivalent to: if (a) { //... } else { if (b) { //... } else { if (c) { //... } else { //... } } }

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  • Dynamic stack allocation in C++

    - by Poni
    I want to allocate memory on the stack. Heard of _alloca / alloca and I understand that these are compiler-specific stuff, which I don't like. So, I came-up with my own solution (which might have it's own flaws) and I want you to review/improve it so for once and for all we'll have this code working: /*#define allocate_on_stack(pointer, size) \ __asm \ { \ mov [pointer], esp; \ sub esp, [size]; \ }*/ /*#define deallocate_from_stack(size) \ __asm \ { \ add esp, [size]; \ }*/ void test() { int buff_size = 4 * 2; char *buff = 0; __asm { // allocate mov [buff], esp; sub esp, [buff_size]; } // playing with the stack-allocated memory for(int i = 0; i < buff_size; i++) buff[i] = 0x11; __asm { // deallocate add esp, [buff_size]; } } void main() { __asm int 3h; test(); } Compiled with VC9. What flaws do you see in it? Me for example, not sure that subtracting from ESP is the solution for "any kind of CPU". Also, I'd like to make the commented-out macros work but for some reason I can't.

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  • Function parameters evaluation order: is undefined behaviour if we pass reference?

    - by bolov
    This is undefined behaviour: void feedMeValue(int x, int a) { cout << x << " " << a << endl; } int main() { int a = 2; int &ra = a; feedMeValue(ra = 3, a); return 0; } because depending on what parameter gets evaluated first we could call (3, 2) or (3, 3). However this: void feedMeReference(int x, int const &ref) { cout << x << " " << ref << endl; } int main() { int a = 2; int &ra = a; feedMeReference(ra = 3, a); return 0; } will always output 3 3 since the second parameter is a reference and all parameters have been evaluated before the function call, so even if the second parameter is evaluated before of after ra = 3, the function received a reference to a wich will have a value of 2 or 3 at the time of the evaluation, but will always have the value 3 at the time of the function call. Is the second example UB? It is important to know because the compiler is free to do anything if he detects undefined behaviour, even if I know it would always yield the same results. *Note: I think that feedMeReference(a = 3, a) is the exact same situation as feedMeReference(ra = 3, a). However it seems not everybody agrees, in the addition to having 2 completely different answers.

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  • Safe and polymorphic toEnum

    - by jetxee
    I'd like to write a safe version of toEnum: safeToEnum :: (Enum t, Bounded t) => Int -> Maybe t A naive implementation: safeToEnum :: (Enum t, Bounded t) => Int -> Maybe t safeToEnum i = if (i >= fromEnum (minBound :: t)) && (i <= fromEnum (maxBound :: t)) then Just . toEnum $ i else Nothing main = do print $ (safeToEnum 1 :: Maybe Bool) print $ (safeToEnum 2 :: Maybe Bool) And it doesn't work: safeToEnum.hs:3:21: Could not deduce (Bounded t1) from the context () arising from a use of `minBound' at safeToEnum.hs:3:21-28 Possible fix: add (Bounded t1) to the context of an expression type signature In the first argument of `fromEnum', namely `(minBound :: t)' In the second argument of `(>=)', namely `fromEnum (minBound :: t)' In the first argument of `(&&)', namely `(i >= fromEnum (minBound :: t))' safeToEnum.hs:3:56: Could not deduce (Bounded t1) from the context () arising from a use of `maxBound' at safeToEnum.hs:3:56-63 Possible fix: add (Bounded t1) to the context of an expression type signature In the first argument of `fromEnum', namely `(maxBound :: t)' In the second argument of `(<=)', namely `fromEnum (maxBound :: t)' In the second argument of `(&&)', namely `(i <= fromEnum (maxBound :: t))' As well as I understand the message, the compiler does not recognize that minBound and maxBound should produce exactly the same type as in the result type of safeToEnum inspite of the explicit type declaration (:: t). Any idea how to fix it?

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  • Qt4Dotnet on Mac OS X

    - by Tony
    Hello everyone. I'm using Qt4Dotnet project in order to port application originally written in C# on Linux and Mac. Port to Linux hasn't taken much efforts and works fine. But Mac (10.4 Tiger) is a bit more stubborn. The problem is: when I try to start my application it throws an exception. Exception states that com.trolltech.qt.QtJambi_LibraryInitializer is unable to find all necessary ibraries. QtJambi library initializer uses java.library.path VM environment variable. This variable includes current working directory. I put all necessary libraries in a working directory. When I try to run the application from MonoDevelop IDE, initializer is able to load one library, but the other libraries are 'missing': An exception was thrown by the type initializer for com.trolltech.qt.QtJambi_LibraryInitializer --- java.lang.RuntimeException: Loading library failed, progress so far: No 'qtjambi-deployment.xml' found in classpath, loading libraries via 'java.library.path' Loading library: 'libQtCore.4.dylib'... - using 'java.library.path' - ok, path was: /Users/chin/test/bin/Debug/libQtCore.4.dylib Loading library: 'libqtjambi.jnilib'... - using 'java.library.path' Both libQtCore.4.dylib and libqtjambi.jnilib are in the same directory. When I try to run it from the command prompt, the initializer is unable to load even libQtCore.4.dylib. I'm using Qt4Dotnet v4.5.0 (currently the latest) with QtJambi v4.5.2 libraries. This might be the source of the problem, but I'm neither able to compile Qt4Dotnet v4.5.2 by myself nor to find QtJambi v4.5.0 libraries. Project's page states that some sort of patch should be applied to QtJambi's source code in order to be compatible with Mono framework, but this patch hasn't been released yet. Without this patch application crashes in a strange manner (other than library seek fault). I must note that original QtJambi loads all necessary libraries perfectly, so it might be issues of IKVM compiler used to translate QtJambi into .Net library. Any suggestions how can I overcome this problem?

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  • Instantiating and starting a Scala Actor in a Map

    - by Bruce Ferguson
    I'm experimenting with a map of actors, and would like to know how to instantiate them and start them in one fell swoop... import scala.actors.Actor import scala.actors.Actor._ import scala.collection.mutable._ abstract class Message case class Update extends Message object Test { val groupings = "group1" :: "group2" :: "group3":: Nil val myActorMap = new HashMap[String,MyActor] def main(args : Array[String]) { groupings.foreach(group => myActorMap += (group -> new MyActor)) myActorMap("group2").start myActorMap("group2") ! Update } } class MyActor extends Actor { def act() { loop { react { case Update => println("Received Update") case _ => println("Ignoring event") } } } } The line: myActorMap("group2").start will grab the second instance, and let me start it, but I would like to be able to do something more like: groupings.foreach(group => myActorMap += (group -> (new MyActor).start)) but no matter how I wrap the new Actor, the compiler complains with something along the lines of: type mismatch; found : scala.actors.Actor required: com.myCompany.test.MyActor or various other complaints. I know it must be something simple to do with anonymous classes, but I can't see it right now. Any suggestions? Thanks in advance!!

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  • How is it legal to reference an undefined type inside a structure?

    - by paxdiablo
    As part of answering another question, I came across a piece of code like this, which gcc compiles without complaint. typedef struct { struct xyz *z; } xyz; int main (void) { return 0; } This is the means I've always used to construct types that point to themselves (e.g., linked lists) but I've always thought you had to name the struct so you could use self-reference. In other words, you couldn't use xyz *z within the structure because the typedef is not yet complete at that point. But this particular sample does not name the structure and it still compiles. I thought originally there was some black magic going on in the compiler that automatically translated the above code because the structure and typedef names were the same. But this little beauty works as well: typedef struct { struct NOTHING_LIKE_xyz *z; } xyz; What am I missing here? This seems a clear violation since there is no struct NOTHING_LIKE_xyz type defined anywhere. When I change it from a pointer to an actual type, I get the expected error: typedef struct { struct NOTHING_LIKE_xyz z; } xyz; qqq.c:2: error: field `z' has incomplete type Also, when I remove the struct, I get an error (parse error before "NOTHING ...). Is this allowed in ISO C?

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  • Is a call to the following method considered late binding?

    - by AspOnMyNet
    1) Assume: • B1 defines methods virtualM() and nonvirtualM(), where former method is virtual while the latter is non-virtual • B2 derives from B1 • B2 overrides virtualM() • B2 is defined inside assembly A • Application app doesn’t have a reference to assembly A In the following code application app dynamically loads an assembly A, creates an instance of a type B2 and calls methods virtualM() and nonvirtualM(): Assembly a=Assembly.Load(“A”); Type t= a.GetType(“B2”); B1 a = ( B1 ) Activator.CreateInstance ( “t” ); a.virtualM(); a.nonvirtualM(); a) Is call to a.virtualM() considered early binding or late binding? b) I assume a call to a.nonvirtualM() is resolved during compilation time? 2) Does the term late binding refer only to looking up the target method at run time or does it also refer to creating an instance of given type at runtime? thanx EDIT: 1) A a=new A(); a.M(); As far as I know, it is not known at compile time where on the heap (thus at which memory address ) will instance a be created during runtime. Now, with early binding the function calls are replaced with memory addresses during compilation process. But how can compiler replace function call with memory address, if it doesn’t know where on the heap will object a be created during runtime ( here I’m assuming the address of method a.M will also be at same memory location as a )? 2) The method slot is determined at compile time I assume that by method slot you’re referring to the entry point in V-table?

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  • How do I mock a method with an open array parameter in PascalMock?

    - by Oliver Giesen
    I'm currently in the process of getting started with unit testing and mocking for good and I stumbled over the following method that I can't seem to fabricate a working mock implementation for: function GetInstance(const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID = CID_DEFAULT): Boolean; (TImplContextID is just an alias for Integer) I thought it would have to look something like this: function TImplementationProviderMock.GetInstance( const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID): Boolean; begin Result := AddCall('GetInstance') .WithParams([@AIID, AContextID]) .ReturnsOutParams([AInstance]) .ReturnValue; end; But the compiler complains about the .ReturnsOutParams([AInstance]) saying "Bad argument type in variable type array constructor.". Also I haven't found a way to specify the open array parameter AArgs at all. Also, is using the @-notation for the TGUID-typed parameter the right way to go? Is it possible to mock this method with the current version of PascalMock at all? Update: I now realize I got the purpose of ReturnsOutParams completely wrong: It's intended to be used for populating the values to be returned when defining the expectations rather than for mocking the call itself. I now think the correct syntax for mocking the out parameter would probably have to look more like this: function TImplementationProviderMock.GetInstance( const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID): Boolean; var lCall: TMockMethod; begin lCall := AddCall('GetInstance').WithParams([@AIID, AContextID]); Pointer(AInstance) := lCall.OutParams[0]; Result := lCall.ReturnValue; end; The questions that remain are how to mock the open array parameter AArgs and whether passing the TGUID argument (i.e. a value type) by address will work out...

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  • C++ Beginner Delete Question

    - by Pooch
    Hi all, This is my first year learning C++ so bear with me. I am attempting to dynamically allocate memory to the heap and then delete the allocated memory. Below is the code that is giving me a hard time: // String.cpp #include "String.h" String::String() {} String::String(char* source) { this->Size = this->GetSize(source); this->CharArray = new char[this->Size + 1]; int i = 0; for (; i < this->Size; i++) this->CharArray[i] = source[i]; this->CharArray[i] = '\0'; } int String::GetSize(const char * source) { int i = 0; for (; source[i] != '\0'; i++); return i; } String::~String() { delete[] this->CharArray; } Here is the error I get when the compiler tries to delete the CharArray: 0xC0000005: Access violation reading location 0xccccccc0. And here is the last call on the stack: msvcr100d.dll!operator delete(void * pUserData) Line 52 + 0x3 bytes C++ I am fairly certain the error exists within this piece of code but will provide you with any other information needed. Oh yeah, using VS 2010 for XP. Thanks for any and all help!

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  • Why my object sees variables which were not given to it in the constructor?

    - by Roman
    I have the following code. Which is "correct" and which I do not understand: private static void updateGUI(final int i, final JLabel label) { SwingUtilities.invokeLater( new Runnable() { public void run() { label.setText("You have " + i + " seconds."); } } ); } I create a new instance of the Runnable class and then in the run method of this instance I use variables label and i. It works, but I do not understand why it work. Why the considered object sees values of these variables. According to my understanding the code should look like that (and its wrong): private static void updateGUI(final int i, final JLabel label) { SwingUtilities.invokeLater(new Runnable(i,label) { public Runnable(int i, JLabel label) { this.i = i; this.label = label; } public void run() { label.setText("You have " + i + " seconds."); } }); } So, I would give the i and label variables to the constructor so the object can access them... By the way, in the updateGUI I use final before the i and label. I think I used final because compiler wanted that. But I do not understand why.

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  • C++0x rvalue references and temporaries

    - by Doug
    (I asked a variation of this question on comp.std.c++ but didn't get an answer.) Why does the call to f(arg) in this code call the const ref overload of f? void f(const std::string &); //less efficient void f(std::string &&); //more efficient void g(const char * arg) { f(arg); } My intuition says that the f(string &&) overload should be chosen, because arg needs to be converted to a temporary no matter what, and the temporary matches the rvalue reference better than the lvalue reference. This is not what happens in GCC and MSVC. In at least G++ and MSVC, any lvalue does not bind to an rvalue reference argument, even if there is an intermediate temporary created. Indeed, if the const ref overload isn't present, the compilers diagnose an error. However, writing f(arg + 0) or f(std::string(arg)) does choose the rvalue reference overload as you would expect. From my reading of the C++0x standard, it seems like the implicit conversion of a const char * to a string should be considered when considering if f(string &&) is viable, just as when passing a const lvalue ref arguments. Section 13.3 (overload resolution) doesn't differentiate between rvalue refs and const references in too many places. Also, it seems that the rule that prevents lvalues from binding to rvalue references (13.3.3.1.4/3) shouldn't apply if there's an intermediate temporary - after all, it's perfectly safe to move from the temporary. Is this: Me misreading/misunderstand the standard, where the implemented behavior is the intended behavior, and there's some good reason why my example should behave the way it does? A mistake that the compiler vendors have somehow all made? Or a mistake based on common implementation strategies? Or a mistake in e.g. GCC (where this lvalue/rvalue reference binding rule was first implemented), that was copied by other vendors? A defect in the standard, or an unintended consequence, or something that should be clarified?

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  • Using JRE 1.5, still maven says annotation not supported in -source 1.3

    - by Abhijeet
    Hi, I am using JRE 1.5. Still when I try to compile my code it fails by saying to use JRE 1.5 instead of 1.3 C:\temp\SpringExamplemvn -e clean install + Error stacktraces are turned on. [INFO] Scanning for projects... [INFO] ------------------------------------------------------------------------ [INFO] Building SpringExample [INFO] task-segment: [clean, install] [INFO] ------------------------------------------------------------------------ [INFO] [clean:clean {execution: default-clean}] [INFO] Deleting directory C:\temp\SpringExample\target [INFO] [resources:resources {execution: default-resources}] [WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent! [INFO] Copying 6 resources [INFO] [compiler:compile {execution: default-compile}] [INFO] Compiling 6 source files to C:\temp\SpringExample\target\classes [INFO] ------------------------------------------------------------------------ [ERROR] BUILD FAILURE [INFO] ------------------------------------------------------------------------ [INFO] Compilation failure C:\temp\SpringExample\src\main\java\com\mkyong\stock\model\Stock.java:[45,9] annotations are not supported in -source 1.3 (try -source 1.5 to enable annotations) @Override [INFO] ------------------------------------------------------------------------ [INFO] Trace org.apache.maven.BuildFailureException: Compilation failure C:\temp\SpringExample\src\main\java\com\mkyong\stock\model\Stock.java:[45,9] annotations are not supported in -source 1.3 (try -source 1.5 to enable annotations) @Override at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:715) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:556) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:535) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:387) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:348) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:180) at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328) at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138) at org.apache.maven.cli.MavenCli.main(MavenCli.java:362) at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:585) at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315) at org.codehaus.classworlds.Launcher.launch(Launcher.java:255) at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430) at org.codehaus.classworlds.Launcher.main(Launcher.java:375) Caused by: org.apache.maven.plugin.CompilationFailureException: Compilation failure C:\temp\SpringExample\src\main\java\com\mkyong\stock\model\Stock.java:[45,9] annotations are not supported in -source 1.3 (try -source 1.5 to enable annotations) @Override at org.apache.maven.plugin.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:516) at org.apache.maven.plugin.CompilerMojo.execute(CompilerMojo.java:114) at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490) at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694) ... 17 more [INFO] ------------------------------------------------------------------------ [INFO] Total time: 2 seconds [INFO] Finished at: Wed Dec 22 10:04:53 IST 2010 [INFO] Final Memory: 9M/16M [INFO] ------------------------------------------------------------------------ C:\temp\SpringExamplejavac -version javac 1.5.0_08 javac: no source files

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  • Why is Delphi unable to infer the type for a parameter TEnumerable<T>?

    - by deepc
    Consider the following declaration of a generic utility class in Delphi 2010: TEnumerableUtils = class public class function InferenceTest<T>(Param: T): T; class function Count<T>(Enumerable: TEnumerable<T>): Integer; overload; class function Count<T>(Enumerable: TEnumerable<T>; Filter: TPredicate<T>): Integer; overload; end; Somehow the compiler type inference seems to have problems here: var I: Integer; L: TList<Integer>; begin TEnumerableUtils.InferenceTest(I); // no problem here TEnumerableUtils.Count(L); // does not compile: E2250 There is no overloaded version of 'Count' that can be called with these arguments TEnumerableUtils.Count<Integer>(L); // compiles fine end; The first call works as expected and T is correctly inferred as Integer. The second call does not work, unless I also add <Integer -- then it works, as can be seen in the third call. Am I doing something wrong or is the type inference in Delphi just not supporting this (I don't think it is a problem in Java which is why expected it to work in Delphi, too).

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  • Visibility of reintroduced constructor

    - by avenmore
    I have reintroduced the form constructor in a base form, but if I override the original constructor in a descendant form, the reintroduced constructor is no longer visible. type TfrmA = class(TForm) private FWndParent: HWnd; public constructor Create(AOwner: TComponent; const AWndParent: Hwnd); reintroduce; overload; virtual; end; constructor TfrmA.Create(AOwner: TComponent; const AWndParent: Hwnd); begin FWndParent := AWndParent; inherited Create(AOwner); end; type TfrmB = class(TfrmA) private public end; type TfrmC = class(TfrmB) private public constructor Create(AOwner: TComponent); override; end; constructor TfrmC.Create(AOwner: TComponent); begin inherited Create(AOwner); end; When creating: frmA := TfrmA.Create(nil, 0); frmB := TfrmB.Create(nil, 0); frmC := TfrmC.Create(nil, 0); // Compiler error My work-around is to override the reintroduced constructor or to declare the original constructor overloaded, but I'd like to understand the reason for this behavior. type TfrmA = class(TForm) private FWndParent: HWnd; public constructor Create(AOwner: TComponent); overload; override; constructor Create(AOwner: TComponent; const AWndParent: Hwnd); reintroduce; overload; virtual; end; type TfrmC = class(TfrmB) private public constructor Create(AOwner: TComponent; const AWndParent: Hwnd); override; end;

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  • How are you using C++0x today? [closed]

    - by Roger Pate
    This is a question in two parts, the first is the most important and concerns now: Are you following the design and evolution of C++0x? What blogs, newsgroups, committee papers, and other resources do you follow? Even where you're not using any new features, how have they affected your current choices? What new features are you using now, either in production or otherwise? The second part is a follow-up, concerning the new standard once it is final: Do you expect to use it immediately? What are you doing to prepare for C++0x, other than as listed for the previous questions? Obviously, compiler support must be there, but there's still co-workers, ancillary tools, and other factors to consider. What will most affect your adoption? Edit: The original really was too argumentative; however, I'm still interested in the underlying question, so I've tried to clean it up and hopefully make it acceptable. This seems a much better avenue than duplicating—even though some answers responded to the argumentative tone, they still apply to the extent that they addressed the questions, and all answers are community property to be cleaned up as appropriate, too.

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  • C89, Mixing Variable Declarations and Code

    - by rutski
    I'm very curious to know why exactly C89 compilers will dump on you when you try to mix variable declarations and code, like this for example: rutski@imac:~$ cat test.c #include <stdio.h> int main(void) { printf("Hello World!\n"); int x = 7; printf("%d!\n", x); return 0; } rutski@imac:~$ gcc -std=c89 -pedantic test.c test.c: In function ‘main’: test.c:7: warning: ISO C90 forbids mixed declarations and code rutski@imac:~$ Yes, you can avoid this sort of thing by staying away from -pedantic. But then your code is no longer standards compliant. And as anybody capable of answering this post probably already knows, this is not just a theoretical concern. Platforms like Microsoft's C compiler enforce this quick in the standard under any and all circumstances. Given how ancient C is, I would imagine that this feature is due to some historical issue dating back to the extraordinary hardware limitations of the 70's, but I don't know the details. Or am I totally wrong there?

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  • What would be different in Java if Enum declaration didn't have the recursive part

    - by atamur
    Please see http://stackoverflow.com/questions/211143/java-enum-definition and http://stackoverflow.com/questions/3061759/why-in-java-enum-is-declared-as-enume-extends-enume for general discussion. Here I would like to learn what exactly would be broken (not typesafe anymore, or requiring additional casts etc) if Enum class was defined as public class Enum<E extends Enum> I'm using this code for testing my ideas: interface MyComparable<T> { int myCompare(T o); } class MyEnum<E extends MyEnum> implements MyComparable<E> { public int myCompare(E o) { return -1; } } class FirstEnum extends MyEnum<FirstEnum> {} class SecondEnum extends MyEnum<SecondEnum> {} With it I wasn't able to find any benefits in this exact case. PS. the fact that I'm not allowed to do class ThirdEnum extends MyEnum<SecondEnum> {} when MyEnum is defined with recursion is a) not relevant, because with real enums you are not allowed to do that just because you can't extend enum yourself b) not true - pls try it in a compiler and see that it in fact is able to compile w/o any errors PPS. I'm more and more inclined to believe that the correct answer here would be "nothing would change if you remove the recursive part" - but I just can't believe that.

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  • Getting zeros between data while reading a binary file in C

    - by indiajoe
    I have a binary data which I am reading into an array of long integers using a C programme. hexdump of the binary data shows, that after first few data points , it starts again at a location 20000 hexa adresses away. hexdump output is as shown below. 0000000 0000 0000 0000 0000 0000 0000 0000 0000 * 0020000 0000 0000 0053 0000 0064 0000 006b 0000 0020010 0066 0000 0068 0000 0066 0000 005d 0000 0020020 0087 0000 0059 0000 0062 0000 0066 0000 ........ and so on... But when I read it into an array 'data' of long integers. by the typical fread command fread(data,sizeof(*data),filelength/sizeof(*data),fd); It is filling up with all zeros in my data array till it reaches the 20000 location. After that it reads in data correctly. Why is it reading regions where my file is not there? Or how will I make it read only my file, not anything inbetween which are not in file? I know it looks like a trivial problem, but I cannot figure it out even after googling one night.. Can anyone suggest me where I am doing it wrong? Other Info : I am working on a gnu/linux machine. (slax-atma distro to be specific) My C compiler is gcc.

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  • Script to install and compile Python, Django, Virtualenv, Mercurial, Git, LessCSS, etc... on Dreamho

    - by tmslnz
    The Story After cleaning up my Dreamhost shared server's home folder from all the cruft accumulated over time, I decided to start afresh and compile/reinstall Python. All tutorials and snippets I found seemed overly simplistic, assuming (or ignoring) a bunch of dependencies needed by Python to compile all modules correctly. So, starting from http://andrew.io/weblog/2010/02/installing-python-2-6-virtualenv-and-virtualenvwrapper-on-dreamhost/ (so far the best guide I found), I decided to write a set-and-forget Bash script to automate this painful process, including along the way a bunch of other things I am planning to use. The Script I am hosting the script on http://bitbucket.org/tmslnz/python-dreamhost-batch/src/ The TODOs So far it runs fine, and does all it needs to do in about 900 seconds, giving me at the end of the process a fully functional Python / Mercurial / etc... setup without even needing to log out and back in. I though this might be of use for others too, but there are a few things that I think it's missing and I am not quite sure how to go for it, what's the best way to do it, or if this just doesn't make any sense at all. Check for errors and break Check for minor version bumps of the packages and give warnings Check for known dependencies Use arguments to install only some of the packages instead of commenting out lines Organise the code in a manner that's easy to update Optionally make the installers and compiling silent, with error logging to file failproof .bashrc modification to prevent breaking ssh logins and having to log back via FTP to fix it EDIT: The implied question is: can anyone, more bashful than me, offer general advice on the worthiness of the above points or highlight any problems they see with this approach? (see my answer to Ry4an's comment below) The Gist I am no UNIX or Bash or compiler expert, and this has been built iteratively, by trial and error. It is somehow going towards apt-get (well, 1% of it...), but since Dreamhost and others obviously cannot give root access on shared servers, this looks to me like a potentially very useful workaround; particularly so with some community work involved.

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  • Ogre material scripts; how do I give a technique multiple lod_indexes?

    - by BlueNovember
    I have an Ogre material script that defines 4 rendering techniques. 1 using GLSL shaders, then 3 others that just use textures of different resolutions. I want to use the GLSL shader unconditionally if the graphics card supports it, and the other 3 textures depending on camera distance. At the moment my script is; material foo { lod_distances 1600 2000 technique shaders { lod_index 0 lod_index 1 lod_index 2 //various passes here } technique high_res { lod_index 0 //various passes here } technique medium_res { lod_index 1 //various passes here } technique low_res { lod_index 2 //various passes here } Extra information The Ogre manual says; Increasing indexes denote lower levels of detail You can (and often will) assign more than one technique to the same LOD index, what this means is that OGRE will pick the best technique of the ones listed at the same LOD index. OGRE determines which one is 'best' by which one is listed first. Currently, on a machine supporting the GLSL version I am using, the script behaves as follows; Camera 2000 : Shader technique Camera 1600 <= 2000 : Medium Camera <= 1600 : High If I change the lod order in shader technique to { lod_index 2 lod_index 1 lod_index 0 } The behaviour becomes; Camera 2000 : Low Camera 1600 <= 2000 : Medium Camera <= 1600 : Shader implying only the latest lod_index is used. If I change it to lod_index 0 1 2 It shouts at me Compiler error: fewer parameters expected in foo.material(#): lod_index only supports 1 argument So how do I specify a technique to have 3 lod_indexes? Duplication works; technique shaders { lod_index 0 //various passes here } technique shaders1 { lod_index 1 //passes repeated here } technique shaders2 { lod_index 2 //passes repeated here } ...but it's ugly.

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  • How to convert many thousands of lines of VBScript to C#?

    - by Ross Patterson
    I have a collection of about 10,000 small VBScript programs (50-100 lines each) and a small collection of larger ones, and I'm looking for a way to convert them to C# without resorting to by-hand transliteration. The programs are automated test cases for a web application, written for HP/Mercury's QuickTest Pro, and I'm trying to turn them into test cases for Selenium. Luckily, the tests appear to be well-written, using a library of building blocks and idioms (the larger programs), so the test cases actually resemble a domain-specific language more than they do VBScript, and the QTP-ness is well-buried inside the libraries. Ideally, what I'm searching for is a tool that can do the syntactic transformation from VBScript to C# for both the dsl-ish test cases and also the more complicated building-block libraries. That would leave me with a manual cleanup of the libraries, and probably very little work on the test cases. If I could find a VBScript-to-VB.NET translator, I'd take that also, as I suspect I could compile the VB.NET and then de-compile to C# using .NET Relector or something similar. Plan B is to write a translator of my own for the test cases, since they're in a very straight-line style, but it wouldn't help with the libraries. Any suyggestions? I haven't written a compiler in at least 15 years, and while I haven't forgotten how, I'm not looking forward to it - least of all for VBScript!

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