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  • Why is there no autorelease pool when I do performSelectorInBackground: ?

    - by Thanks
    I am calling a method that goes in a background thread: [self performSelectorInBackground:@selector(loadViewControllerWithIndex:) withObject:[NSNumber numberWithInt:viewControllerIndex]]; then, I have this method implementation that gets called by the selector: - (void) loadViewControllerWithIndex:(NSNumber *)indexNumberObj { NSAutoreleasePool *arPool = [[NSAutoreleasePool alloc] init]; NSInteger vcIndex = [indexNumberObj intValue]; Class c; UIViewController *controller = [viewControllers objectAtIndex:vcIndex]; switch (vcIndex) { case 0: c = [MyFirstViewController class]; break; case 1: c = [MySecondViewController class]; break; default: NSLog(@"unknown index for loading view controller: %d", vcIndex); // error break; } if ((NSNull *)controller == [NSNull null]) { controller = [[c alloc] initWithNib]; [viewControllers replaceObjectAtIndex:vcIndex withObject:controller]; [controller release]; } if (controller.view.superview == nil) { UIView *placeholderView = [viewControllerPlaceholderViews objectAtIndex:vcIndex]; [placeholderView addSubview:controller.view]; } [arPool release]; } Althoug I do create an autorelease pool there for that thread, I always get this error: 2009-05-30 12:03:09.910 Demo[1827:3f03] *** _NSAutoreleaseNoPool(): Object 0x523e50 of class NSCFNumber autoreleased with no pool in place - just leaking Stack: (0x95c83f0f 0x95b90442 0x28d3 0x2d42 0x95b96e0d 0x95b969b4 0x93a00155 0x93a00012) If I take away the autorelease pool, I get a whole bunch of messages like these. I also tried to create an autorelease pool around the call of the performSelectorInBackground:, but that doesn't help. I suspect the parameter, but I don't know why the compiler complains about an NSCFNumber. Am I missing something? My Instance variables are all "nonatomic". Can that be a problem? UPDATE: I may also suspect that some variable has been added to an autorelease pool of the main thread (maybe an ivar), and now it trys to release that one inside the wrong autorelease pool? If so, how could I fix that? (damn, this threading stuff is complex ;) )

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  • How can I make a Maybe-Transformer MaybeT into an instance of MonadWriter?

    - by martingw
    I am trying to build a MaybeT-Transformer Monad, based on the example in the Real World Haskell, Chapter Monad Transformers: data MaybeT m a = MaybeT { runMT :: m (Maybe a) } instance (Monad m) => Monad (MaybeT m) where m >>= f = MaybeT $ do a <- runMT m case a of Just x -> runMT (f x) Nothing -> return Nothing return a = MaybeT $ return (Just a) instance MonadTrans MaybeT where lift m = MaybeT $ do a <- m return (Just a) This works fine, but now I want to make MaybeT an instance of MonadWriter: instance (MonadWriter w m) => MonadWriter w (MaybeT m) where tell = lift . tell listen m = MaybeT $ do unwrapped <- listen (runMT m) return (Just unwrapped) The tell is ok, but I can't get the listen function right. The best I could come up with after 1 1/2 days of constructor origami is the one you see above: unwrapped is supposed to be a tuple of (Maybe a, w), and that I want to wrap up in a Maybe-Type and put the whole thing in an empty MonadWriter. But the compiler complains with: Occurs check: cannot construct the infinite type: a = Maybe a When generalising the type(s) for `listen' In the instance declaration for `MonadWriter w (MaybeT m)' What am I missing?

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  • how do i execute a stored procedure with vici coolstorage?

    - by lincolnk
    I'm building an app around Vici Coolstorage (asp.net version). I have my classes created and mapped to my database tables and can pull a list of all records fine. I've written a stored procedure where the query jumps across databases that aren't mapped with Coolstorage, however, the fields in the query result map directly to one of my classes. The procedure takes 1 parameter. so 2 questions here: how do i execute the stored procedure? i'm doing this CSParameterCollection collection = new CSParameterCollection(); collection.Add("@id", id); var result = Vici.CoolStorage.CSDatabase.RunQuery("procedurename", collection); and getting the exception "Incorrect syntax near 'procedurename'." (i'm guessing this is because it's trying to execute it as text rather than a procedure?) and also, since the class representing my table is defined as abstract, how do i specify that result should create a list of MyTable objects instead of generic or dynamic or whatever objects? if i try Vici.CoolStorage.CSDatabase.RunQuery<MyTable>(...) the compiler yells at me for it being an abstract class.

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  • Linker, Libraries & Directories Information

    - by m00st
    I've finished both my C++ 1/2 classes and we did not cover anything on Linking to libraries or adding additional libraries to C++ code. I've been having a hay-day trying to figure this out; I've been unable to find basic information linking to objects. Initially I thought the problem was the IDE (Netbeans; and Code::Blocks). However I've been unable to get wxWidgets and GTKMM setup. Can someone point me in the right direction on the terminology and basic information about #including files and linking files in a Cpp application? Basically I want/need to know everything in regards to this process. The difference between .dll, .lib, .o, .lib.a, .dll.a. The difference between a .h and a "library" (.dll, .lib correct?) I understand I need to read the compiler documentation I am using; however all compilers (that I know of) use linker and headers; I need to learn this information. Please point me in the right direction! :] So far on my quest I've found out: Linker links libraries already compiled to your project. .a files are static libraries (.lib in windows) .dll in windows is a shared library (.so in *nix) Thanks

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  • Binding type variables that only occur in assertions

    - by Giuseppe Maggiore
    Hi! I find it extremely difficult to describe my problem, so here goes nothing: I have a bunch of assertions on the type of a function. These assertions rely on a type variable that is not used for any parameter of the function, but is only used for internal bindings. Whenever I use this function it does not compile because, of course, the compiler has no information from which to guess what type to bind my type variable. Here is the code: {-# LANGUAGE MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances, UndecidableInstances, FlexibleContexts, EmptyDataDecls, ScopedTypeVariables, TypeOperators, TypeSynonymInstances #-} class C a a' where convert :: a -> a' class F a b where apply :: a -> b class S s a where select :: s -> a data CInt = CInt Int instance S (Int,String) Int where select (i,_) = i instance F Int CInt where apply = CInt f :: forall s a b . (S s a, F a b) => s -> b f s = let v = select s :: a y = apply v :: b in y x :: Int x = f (10,"Pippo") And here is the generated error: FunctorsProblems.hs:21:4: No instances for (F a Int, S (t, [Char]) a) arising from a use of `f' at FunctorsProblems.hs:21:4-17 Possible fix: add an instance declaration for (F a Int, S (t, [Char]) a) In the expression: f (10, "Pippo") In the definition of `x': x = f (10, "Pippo") Failed, modules loaded: none. Prelude>

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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 to use pure in D 2.0

    - by James Dean
    While playing around with D 2.0 I found the following problem: Example 1: pure string[] run1() { string[] msg; msg ~= "Test"; msg ~= "this."; return msg; } This compiles and works as expected. When I try to wrap the string array in a class I find I can not get this to work: class TestPure { string[] msg; void addMsg( string s ) { msg ~= s; } }; pure TestPure run2() { TestPure t = new TestPure(); t.addMsg("Test"); t.addMsg("this."); return t; } This code will not compile because the addMsg function is impure. I can not make that function pure since it alters the TestPure object. Am i missing something? Or is this a limitation? The following does compile: pure TestPure run3() { TestPure t = new TestPure(); t.msg ~= "Test"; t.msg ~= "this."; return t; } Would the ~= operator not been implemented as a impure function of the msg array? How come the compiler does not complain about that in the run1 function?

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  • Enforce strong type checking in C (type strictness for typedefs)

    - by quinmars
    Is there a way to enforce explicit cast for typedefs of the same type? I've to deal with utf8 and sometimes I get confused with the indices for the character count and the byte count. So it be nice to have some typedefs: typedef unsigned int char_idx_t; typedef unsigned int byte_idx_t; With the addition that you need an explicit cast between them: char_idx_t a = 0; byte_idx_t b; b = a; // compile warning b = (byte_idx_t) a; // ok I know that such a feature doesn't exist in C, but maybe you know a trick or a compiler extension (preferable gcc) that does that. EDIT: I still don't really like the Hungarian notation in general, I couldn't used it for this problem because of project coding conventions, but I used it now in another similar case, where also the types are the same and the meanings are very similar. And I have to admit: it helps. I never would go and declare every integer with a starting "i", but as in Joel's example for overlapping types, it can be life saving.

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  • C++ Unary - Operator Overload Won't Compile

    - by Brian Hooper
    I am attempting to create an overloaded unary - operator but can't get the code to compile. A cut-down version of the code is as follows:- class frag { public: frag myfunc (frag oper1, frag oper2); frag myfunc2 (frag oper1, frag oper2); friend frag operator + (frag &oper1, frag &oper2); frag operator - () { frag f; f.element = -element; return f; } private: int element; }; frag myfunc (frag oper1, frag oper2) { return oper1 + -oper2; } frag myfunc2 (frag oper1, frag oper2) { return oper1 + oper2; } frag operator+ (frag &oper1, frag &oper2) { frag innerfrag; innerfrag.element = oper1.element + oper2.element; return innerfrag; } The compiler reports... /home/brian/Desktop/frag.hpp: In function ‘frag myfunc(frag, frag)’: /home/brian/Desktop/frag.hpp:41: error: no match for ‘operator+’ in ‘oper1 + oper2.frag::operator-()’ /home/brian/Desktop/frag.hpp:16: note: candidates are: frag operator+(frag&, frag&) Could anyone suggest what I need to be doing here? Thanks.

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  • linq - how to sort a list

    - by Billy Logan
    Hello everyone, I have a linq query that populates a list of designers. since i am using the filters below my sorting is not functioning properly. My question is with the given code below how can i best sort this List after the fact or sort while querying? I have tried to sort the list after the fact using the following script but i receive a compiler error: List<TBLDESIGNER> designers = new List<TBLDESIGNER>(); designers = 'calls my procedure below and comes back with an unsorted list of designers' designers.Sort((x, y) => string.Compare(x.FIRST_NAME, y.LAST_NAME)); Query goes as follows: List<TBLDESIGNER> designer = null; using (SOAE strikeOffContext = new SOAE()) { //Invoke the query designer = AdminDelegates.selectDesignerDesigns.Invoke(strikeOffContext).ByActive(active).ByAdmin(admin).ToList(); } Delegate: public static Func<SOAE, IQueryable<TBLDESIGNER>> selectDesignerDesigns = CompiledQuery.Compile<SOAE, IQueryable<TBLDESIGNER>>( (designer) => from c in designer.TBLDESIGNER.Include("TBLDESIGN") orderby c.FIRST_NAME ascending select c); Filter ByActive: public static IQueryable<TBLDESIGNER> ByActive(this IQueryable<TBLDESIGNER> qry, bool active) { //Return the filtered IQueryable object return from c in qry where c.ACTIVE == active select c; } Filter ByAdmin: public static IQueryable<TBLDESIGNER> ByAdmin(this IQueryable<TBLDESIGNER> qry, bool admin) { //Return the filtered IQueryable object return from c in qry where c.SITE_ADMIN == admin select c; } Thanks in advance, Billy

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  • Error when compiling a WinForms project that uses SubSonic library

    - by Mike Devenney
    The code generation is working but I get the following errors when I try to build the project: Error 4 Source file '...Project Path...\Structs.cs' could not be opened ('Unspecified error ') PPSGenerator Error 5 Source file '...Project Path...\Context.cs' could not be opened ('Unspecified error ') PPSGenerator Error 6 Source file '...Project Path...\ActiveRecord.cs' could not be opened ('Unspecified error ') PPSGenerator Error 7 Source file '...Project Path...\StoredProcedures.cs' could not be opened ('Unspecified error ') PPSGenerator I'm using VS2010 on a Windows 7 64 bit machine. Project is targeting Framework 3.5... any ideas? Also noticed the following warnings, but not sure that these are as important: Warning 1 The C# 2.0 and C# 3.5 compilers are no longer supported. Templates will always be compiled with the version 4 compiler instead of 'v3.5' as specified. ...ProjectPath...\Structs.tt 1 4 Warning 2 Multiple template directives were found in the template. All but the first one will be ignored. Multiple parameters to the template directive should be specified within one template directive. ...ProjectPath...\Settings.ttinclude 1 4 Warning 3 Compiling transformation: The variable 'parameters' is assigned but its value is never used ...ProjectPath...\SQLServer.ttinclude 92 15 Thanks! Mike D

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  • actionscript-3: refactor interface inheritance to get rid of ambiguous reference error

    - by maxmc
    hi! imagine there are two interfaces arranged via composite pattern, one of them has a dispose method among other methods: interface IComponent extends ILeaf { ... function dispose() : void; } interface ILeaf { ... } some implementations have some more things in common (say an id) so there are two more interfaces: interface ICommonLeaf extends ILeaf { function get id() : String; } interface ICommonComponent extends ICommonLeaf, IComponent { } so far so good. but there is another interface which also has a dispose method: interface ISomething { ... function dispose() : void; } and ISomething is inherited by ICommonLeaf: interface ICommonLeaf extends ILeaf, ISomething { function get id() : String; } As soon as the dispose method is invoked on an instance which implements the ICommonComponent interface, the compiler fails with an ambiguous reference error because ISomething has a method called dispose and ILeaf also has a dispose method, both living in different interfaces (IComponent, ISomething) within the inheritace tree of ICommonComponent. I wonder how to deal with the situation if the IComponent, the ILeaf and the ISomething can't change. the composite structure must also work for for the ICommonLeaf & ICommonComponent implementations and the ICommonLeaf & ICommonComponent must conform to the ISomething type. this might be an actionscript-3 specific issue. i haven't tested how other languages (for instance java) handle stuff like this.

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  • How can I create an executable to run on a certain processor architecture (instead of certain OS)?

    - by CrazyJugglerDrummer
    So I take my C++ program in Visual studio, compile, and it'll spit out a nice little EXE file. But EXEs will only run on windows, and I hear a lot about how C/C++ compiles into assembly language, which is runs directly on a processor. The EXE runs with the help of windows, or I could have a program that makes an executable that runs on a mac. But aren't I compiling C++ code into assembly language, which is processor specific? My Insights: I'm guessing I'm probably not. I know there's an Intel C++ compiler, so would it make processor-specific assembly code? EXEs run on windows, so they advantage of tons of things already set up, from graphics packages to the massive .NET framework. A processor-specific executable would be literally starting from scratch, with just the instruction set of the processor. Would this executable be a file-type? We could be running windows and open it, but then would control switch to processor only? I assume this executable would be something like an operating system, in that it would have to be run before anything else was booted up, and have only the processor instruction set to "use".

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  • How to pass a Dictionary variable to another procedure

    - by salvationishere
    I am developing a C# VS2008/SQL Server website application. I've never used the Dictionary class before, but I am trying to replace my Hashtable with a Dictionary variable. Here is a portion of my aspx.cs code: ... Dictionary<string, string> openWith = new Dictionary<string, string>(); for (int col = 0; col < headers.Length; col++) { @temp = (col + 1); @tempS = @temp.ToString(); @tempT = "@col" + @temp.ToString(); ... openWith.Add(@tempT, headers[col]); } ... for (int r = 0; r < myInputFile.Rows.Count; r++) { resultLabel.Text = ADONET_methods.AppendDataCT(myInputFile, openWith); } But this is giving me a compiler error on this last line: Argument '2': cannot convert from 'System.Collections.Generic.Dictionary' to 'string' How do I pass the entire openWith variable to AppendDataCT? AppendDataCT is the method that calls my SQL stored proc. I want to pass in the whole row where each row has a unique set of values that I want to add to my database table. For example, if each row requires values for cells A, B, and C, then I want to pass these 3 values to AppendDataCT, where all of these values are strings. How do I do this with Dictionary?

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  • Static library not included in resulting LLVM executable

    - by Matthew Glubb
    Hi, I am trying to compile a c program using LLVM and I am having trouble getting some static libraries included. I have successfully compiled those static libraries using LLVM and, for example, libogg.a is present, as is ogg.l.bc. However, when I try to build the final program, it does not include the static ogg library. I've tried various compiler options with the most notable being: gcc oggvorbis.c -O3 -Wall -I$OV_DIR/include -l$OV_DIR/lib/libogg.a -l$OV_DIR/lib/libvorbis.a -o test.exe This results in the following output (directories shortened for brevity): $OV_DIR/include/vorbis/vorbisfile.h:75: warning: ‘OV_CALLBACKS_DEFAULT’ defined but not used $OV_DIR/include/vorbis/vorbisfile.h:82: warning: ‘OV_CALLBACKS_NOCLOSE’ defined but not used $OV_DIR/include/vorbis/vorbisfile.h:89: warning: ‘OV_CALLBACKS_STREAMONLY’ defined but not used $OV_DIR/include/vorbis/vorbisfile.h:96: warning: ‘OV_CALLBACKS_STREAMONLY_NOCLOSE’ defined but not used llvm-ld: warning: Cannot find library '$OV_DIR/lib/ogg.l.bc' llvm-ld: warning: Cannot find library '$OV_DIR/lib/vorbis.l.bc' WARNING: While resolving call to function 'main' arguments were dropped! I find this perplexing because $OV_DIR/lib/ogg.l.bc DOES exit, as does vorbis.l.bc and they are both readable (as are their containing directories) by everyone. Does anyone have any idea with what I am doing wrong? Thanks, Matt

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  • {DCC Warning} W1036 Variable '$frame' might not have been initialized?

    - by Gad D Lord
    Any ideas why I get this warning in Delphi XE: [DCC Warning] Form1.pas(250): W1036 Variable '$frame' might not have been initialized procedure TForm1.Action1Execute(Sender: TObject); var Thread: TThread; begin ... Thread := TThread.CreateAnonymousThread( procedure{Anonymos}() procedure ShowLoading(const Show: Boolean); begin /// <------------- WARNING IS GIVEN FOR THIS LINE (line number 250) Thread.Synchronize(Thread, procedure{Anonymous}() begin ... Button1.Enabled := not Show; ... end ); end; var i: Integer; begin ShowLoading(true); try Thread.Synchronize(Thread, procedure{Anonymous}() begin ... // some UI updates end Thread.Synchronize(Thread, procedure{Anonymous}() begin ... // some UI updates end ); finally ShowLoading(false); end; end ).NameThread('Some Thread Name'); Thread.Start; end; I do not have anywhere in my code a variable names frame nor $frame. I am even not sure how $frame with $ sign can be a valid identifier. Smells like compiler magic to me. PS: Of course the real life xosw is having other than Form1, Button1, Action1 names.

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  • What's wrong with this code

    - by javacode
    I am getting the compiler error. Can anybody debug this? import javax.mail.*; import javax.mail.internet.*; import java.util.*; public class SendMail { public static void main(String [] args) { SendMail sm=new SendMail(); sm.postMail("[email protected]","hi","hello","[email protected]"); } public void postMail( String recipients[ ], String subject, String message , String from) throws MessagingException { boolean debug = false; //Set the host smtp address Properties props = new Properties(); props.put("mail.smtp.host", "webmail.emailmyname.com"); // create some properties and get the default Session Session session = Session.getDefaultInstance(props, null); session.setDebug(debug); // create a message Message msg = new MimeMessage(session); // set the from and to address InternetAddress addressFrom = new InternetAddress(from); msg.setFrom(addressFrom); InternetAddress[] addressTo = new InternetAddress[recipients.length]; for (int i = 0; i < recipients.length; i++) { addressTo[i] = new InternetAddress(recipients[i]); } msg.setRecipients(Message.RecipientType.TO, addressTo); // Optional : You can also set your custom headers in the Email if you Want msg.addHeader("MyHeaderName", "myHeaderValue"); // Setting the Subject and Content Type msg.setSubject(subject); msg.setContent(message, "text/plain"); Transport.send(msg); } }

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  • Casting to a struct from LPVOID - C

    - by Jamie Keeling
    Hello, I am writing a simple console application which will allow me to create a number of threads from a set of parameters passed through the arguments I provide. DWORD WINAPI ThreadFunc(LPVOID threadData) { } I am packing them into a struct and passing them as a parameter into the CreateThread method and trying to unpack them by casting them to the same type as my struct from the LPVOID. I'm not sure how to cast it to the struct after getting it through so I can use it in the method itself, i've tried various combinations (Example attatched) but it won't compile. Struct: #define numThreads 1 struct Data { int threads; int delay; int messages; }; Call to method: HANDLE hThread; DWORD threadId; struct Data *tData; tData->threads = numThreads; tData->messages = 3; tData->delay = 1000; // Create child thread hThread = CreateThread( NULL, // lpThreadAttributes (default) 0, // dwStackSize (default) ThreadFunc, // lpStartAddress &tData, // lpParameter 0, // dwCreationFlags &threadId // lpThreadId (returned by function) ); My attempt: DWORD WINAPI ThreadFunc(LPVOID threadData) { struct Data tData = (struct Data)threadData; int msg; for(msg = 0; msg<5; msg++) { printf("Message %d from child\n", msg); } return 0; } Compiler error: error C2440: 'type cast' : cannot convert from 'LPVOID' to 'Data' As you can see I have implemented a way to loop through a number of messages already, I'm trying to make things slightly more advanced and add some further functionality.

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  • Compile time float packing/punning

    - by detly
    I'm writing C for the PIC32MX, compiled with Microchip's PIC32 C compiler (based on GCC 3.4). My problem is this: I have some reprogrammable numeric data that is stored either on EEPROM or in the program flash of the chip. This means that when I want to store a float, I have to do some type punning: typedef union { int intval; float floatval; } IntFloat; unsigned int float_as_int(float fval) { IntFloat intf; intf.floatval = fval; return intf.intval; } // Stores an int of data in whatever storage we're using void StoreInt(unsigned int data, unsigned int address); void StoreFPVal(float data, unsigned int address) { StoreInt(float_as_int(data), address); } I also include default values as an array of compile time constants. For (unsigned) integer values this is trivial, I just use the integer literal. For floats, though, I have to use this Python snippet to convert them to their word representation to include them in the array: import struct hex(struct.unpack("I", struct.pack("f", float_value))[0]) ...and so my array of defaults has these indecipherable values like: const unsigned int DEFAULTS[] = { 0x00000001, // Some default integer value, 1 0x3C83126F, // Some default float value, 0.005 } (These actually take the form of X macro constructs, but that doesn't make a difference here.) Commenting is nice, but is there a better way? It's be great to be able to do something like: const unsigned int DEFAULTS[] = { 0x00000001, // Some default integer value, 1 COMPILE_TIME_CONVERT(0.005), // Some default float value, 0.005 } ...but I'm completely at a loss, and I don't even know if such a thing is possible. Notes Obviously "no, it isn't possible" is an acceptable answer if true. I'm not overly concerned about portability, so implementation defined behaviour is fine, undefined behaviour is not (I have the IDB appendix sitting in front of me). As fas as I'm aware, this needs to be a compile time conversion, since DEFAULTS is in the global scope. Please correct me if I'm wrong about this.

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  • Pointer Implementation Details in C

    - by Will Bickford
    I would like to know architectures which violate the assumptions I've listed below. Also I would like to know if any of the assumptions are false for all architectures (i.e. if any of them are just completely wrong). sizeof(int *) == sizeof(char *) == sizeof(void *) == sizeof(func_ptr *) The in-memory representation of all pointers for a given architecture is the same regardless of the data type pointed to. The in-memory representation of a pointer is the same as an integer of the same bit length as the architecture. Multiplication and division of pointer data types are only forbidden by the compiler. NOTE: Yes I know this is nonsensical. What I mean is - is there hardware support to forbid this incorrect usage? All pointer values can be casted to a single integer. In other words, what architectures still make use of segments and offsets? Incrementing a pointer is equivalent to adding sizeof(the pointed data type) to the memory address stored by the pointer. If p is an int32* then p+1 is equal to the memory address 4 bytes after p. I'm most used to pointers being used in a contiguous, virtual memory space. For that usage, I can generally get by thinking of them as addresses on a number line. See (http://stackoverflow.com/questions/1350471/pointer-comparison/1350488#1350488).

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  • VB.NET switching from ADO.NET to LINQ

    - by Cj Anderson
    I'm VERY new to Linq. I have an application I wrote that is in VB.NET 2.0. Works great, but I'd like to switch this application to Linq. I use ADO.NET to load XML into a datatable. The XML file has about 90,000 records in it. I then use the Datatable.Select to perform searches against that Datatable. The search control is a free form textbox. So if the user types in terms it searches instantly. Any further terms that are typed in continue to restrict the results. So you can type in Bob, or type in Bob Barker. Or type in Bob Barker Price is Right. The more criteria typed in the more narrowed your result. I bind the results to a gridview. Moving forward what all do I need to do? From a high level, I assume I need to: 1) Go to Project Properties -- Advanced Compiler Settings and change the Target framework to 3.5 from 2.0. 2) Add the reference to System.XML.Linq, Add the Imports statement to the classes. So I'm not sure what the best approach is going forward after that. I assume I use XDocument.Load, then my search subroutine runs against the XDocument. Do I just do the standard Linq query for this sort of repeated search? Like so: var people = from phonebook in doc.Root.Elements("phonebook") where phonebook.Element("userid") = "whatever" select phonebook; Any tips on how to best implement?

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  • How do I install websocket module for Node.js on Debian VPS?

    - by Ollie Shaw
    I currently am renting a VPS from Dreamhost which runs Debian. I am still learning command line on this OS, but fast! I have successfully installed Node.js, now I want to install the websocket module found here: https://github.com/Worlize/WebSocket-Node From the root user, I have run the following command: npm install websocket The error thrown is: [websocket v1.0.7] Native code compile failed!! On Windows, native extensions require Visual Studio and Python. On Unix, native extensions require Python, make and a C++ compiler. Start npm with --websocket:verbose to show compilation output (if any). What commands should I issue to install this websocket module and its requirements? Thanks very much! Edit: When I run sudo apt-get install gcc make I get this message: Reading package lists... Done Building dependency tree Reading state information... Done gcc is already the newest version. gcc set to manually installed. make is already the newest version. 0 upgraded, 0 newly installed, 0 to remove and 44 not upgraded. And the same error when trying to install WebSocket.

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  • Potential g++ template bug?

    - by Evan Teran
    I've encountered some code which I think should compile, but doesn't. So I'm hoping some of the local standards experts here at SO can help :-). I basically have some code which resembles this: #include <iostream> template <class T = int> class A { public: class U { }; public: U f() const { return U(); } }; // test either the work around or the code I want... #ifndef USE_FIX template <class T> bool operator==(const typename A<T>::U &x, int y) { return true; } #else typedef A<int> AI; bool operator==(const AI::U &x, int y) { return true; } #endif int main() { A<int> a; std::cout << (a.f() == 1) << std::endl; } So, to describe what is going on here. I have a class template (A) which has an internal class (U) and at least one member function which can return an instance of that internal class (f()). Then I am attempting to create an operator== function which compares this internal type to some other type (in this case an int, but it doesn't seem to matter). When USE_FIX is not defined I get the following error: test.cc: In function 'int main()': test.cc:27:25: error: no match for 'operator==' in 'a.A<T>::f [with T = int]() == 1' Which seems odd, because I am clearly (I think) defining a templated operator== which should cover this, in fact if I just do a little of the work for the compiler (enable USE_FIX), then I no longer get an error. Unfortunately, the "fix" doesn't work generically, only for a specific instantiation of the template. Is this supposed to work as I expected? Or is this simply not allowed? BTW: if it matters I am using gcc 4.5.2.

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  • PDCurses TUI with C++ Win32 console application

    - by Bach
    I have downloaded pdcurses source and was able to successfully include curses.h in my project, linked the pre-compiled library and all good. After few hours of trying out the library, I saw the tuidemo.c in the demos folder, compiled it into an executable and brilliant! exactly what I needed for my project. Now the problem is that it's a C code, and I am working on a C++ project in VS c++ 2008. The files I need are tui.c and tui.h How can I include that C file in my C++ code? I saw few suggestions here but the compiler was not too happy with 100's of warnings and errors. How can I go on including/using that TUI pdcurses includes!? Thanks EDIT: I added extern "C" statement, so my test looks like this now, but I'm getting some other type of error #include <stdio.h> #include <stdlib.h> using namespace std; extern "C" { #include <tui.h> } void sub0(void) { //do nothing } void sub1(void) { //do nothing } int main (int argc, char * const argv[]) { menu MainMenu[] = { { "Asub", sub0, "Go inside first submenu" }, { "Bsub", sub1, "Go inside second submenu" }, { "", (FUNC)0, "" } /* always add this as the last item! */ }; startmenu(MainMenu, "TUI - 'textual user interface' demonstration program"); return 0; } Although it is compiling successfully, it is throwing an Error at runtime: 0xC0000005: Access violation reading location 0x021c52f9 at line startmenu(MainMenu, "TUI - 'textual user interface' demonstration program"); Not sure where to go from here. thanks again.

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  • how to templatize partial template specializations?

    - by Kyle
    I'm not even sure what title to give this question; hopefully the code will demonstrate what I'm trying to do: #include <string> #include <list> using namespace std; template<typename A> class Alpha { public: A m_alpha_a; }; template<typename B> class Bravo { public: B m_bravo_b; }; template<> class Alpha<string> { public: string m_alpha_string; }; template<typename B> template<> class Alpha<Bravo<B> > { public: Bravo<B> m_bravo_class; // Line A }; int main() { Alpha<int> alpha_int; alpha_int.m_alpha_a= 4; Alpha<string> alpha_string; alpha_string.m_alpha_string = "hi"; Alpha<Bravo<int> > alpha_bravo_int; alpha_bravo_int.m_bravo_class.m_bravo_b = 9; }; I want to write a specialization for Alpha<A> when A is of any type Bravo<B>, but the compiler says invalid explicit specialization before ‘’ token enclosing class templates are not explicitly specialized (Referring to // Line A.) What's the correct syntax to do what I want?

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