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  • Componentizing complex functionality in an MVC web app

    - by NXT
    Hi Everyone, This is question about MVC web-app architecture, and how it can be extended to handle componentizing moderately complex units of functionality. I have an MVC style web-app with a customer facing credit card charge page. I've been asked to allow the admins to enter credit card payments as well, for times when credit cards are taken over the phone. The customer facing credit card charge section of the website is currently it's own controller, with approximately 3 pages and a login. That controller is responsible for: Customer login credential authentication Credit card data collection Calling a library to do the actual charge. reporting the results to the user. I would like to extract the card data collection pages into a component of some kind so that I can easily reuse the code on the admin side of the app. Right now my components are limited to single "view" pages with PHP style embedded Perl code. This is a simple, custom MVC framework written in Perl. Right now, controllers are called directly from the framework to service web requests. My idea is to allow controllers to be called from other controllers, so that I can componentize more complex functionality. For simplicity I think I prefer composition over inheritance, even though it will require writing a bunch of pass-through methods (actions). Being Perl, I could in theory do multiple inheritance. I'm wondering if anyone with experience in other MVC web frameworks can comment on how this sort of thing is usually done. Thank you.

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  • Why aren't operator conversions implicitly called for templated functions? (C++)

    - by John Gordon
    I have the following code: template <class T> struct pointer { operator pointer<const T>() const; }; void f(pointer<const float>); template <typename U> void tf(pointer<const float>); void g() { pointer<float> ptr; f(ptr); tf(ptr); } When I compile the code with gcc 4.3.3 I get a message (aaa.cc:17: error: no matching function for call to ‘tf(pointer<float>&)’) indicating that the compiler called 'operator pointer<const T>' for the non-templated function f(), but didn't for the templated function tf(). Why and is there any workaround short of overloading tf() with a const and non-const version? Thanks in advance for any help.

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  • File IO, Handling CRLF

    - by aCuria
    Hi, i am writing a program that takes a file and splits it up into multiple small files of a user specified size, then join the multiple small files back again. 1) the code must work for c, c++ 2) i am compiling with multiple compilers. I am reading and writing to the files by using the stl functions fread() and fwrite() The problem I am having pertains to CRLF. If the file I am reading from contains CRLF, then I want to retain it when i split and join the files back together. If the file contains LF, then i want to retain LF. Unfortunately, fread() seems to store CRLF as \n (I think), and whatever is written by fwrite() is compiler-dependent. How do i approach this problem? Thanks.

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  • What should I do if a IOException is thrown?

    - by Roman
    I have the following 3 lines of the code: ServerSocket listeningSocket = new ServerSocket(earPort); Socket serverSideSocket = listeningSocket.accept(); BufferedReader in = new BufferedReader(new InputStreamReader(serverSideSocket.getInputStream())); The compiler complains about all of these 3 lines and its complain is the same for all 3 lines: unreported exception java.io.IOException; In more details, these exception are thrown by new ServerSocket, accept() and getInputStream(). I know I need to use try ... catch .... But for that I need to know what this exceptions mean in every particular case (how should I interpret them). When they happen? I mean, not in general, but in these 3 particular cases.

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  • How do I include extremely long literals in C++ source?

    - by BillyONeal
    Hello everyone :) I've got a bit of a problem. Essentially, I need to store a large list of whitelisted entries inside my program, and I'd like to include such a list directly -- I don't want to have to distribute other libraries and such, and I don't want to embed the strings into a Win32 resource, for a bunch of reasons I don't want to go into right now. I simply included my big whitelist in my .cpp file, and was presented with this error: 1>ServicesWhitelist.cpp(2807): fatal error C1091: compiler limit: string exceeds 65535 bytes in length The string itself is about twice this allowed limit by VC++. What's the best way to include such a large literal in a program?

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  • EHsc vc EHa (synchronous vs asynchronous exception handling)

    - by watson1180
    Could you give a bullet list of practical differences/implication? I read relevant MSDN article, but my understanding asynchronous exceptions is still a bit hazy. I am writing a test suite using Boost.Test and my compiler emits a warning that EHa should be enabled: warning C4535: calling _set_se_translator() requires /EHa The project itself uses only plain exceptions (from STL) and doesn't need /EHa switch. Do I have to recompile it with /EHa switch to make the test suite work properly? My feeling is that I need /EHa for the test suit only. Thank you and happy new year.

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  • NES Programming - Nametables?

    - by Jeffrey Kern
    Hello everyone, I'm wondering about how the NES displays its graphical muscle. I've researched stuff online and read through it, but I'm wondering about one last thing: Nametables. Basically, from what I've read, each 8x8 block in a NES nametable points to a location in the pattern table, which holds graphic memory. In addition, the nametable also has an attribute table which sets a certain color palette for each 16x16 block. They're linked up together like this: (assuming 16 8x8 blocks) Nametable, with A B C D = pointers to sprite data: ABBB CDCC DDDD DDDD Attribute table, with 1 2 3 = pointers to color palette data, with < referencing value to the left, ^ above, and ' to the left and above: 1<2< ^'^' 3<3< ^'^' So, in the example above, the blocks would be colored as so 1A 1B 2B 2B 1C 1D 2C 2C 3D 3D 3D 3D 3D 3D 3D 3D Now, if I have this on a fixed screen - it works great! Because the NES resolution is 256x240 pixels. Now, how do these tables get adjusted for scrolling? Because Nametable 0 can scroll into Nametable 1, and if you keep scrolling Nametable 0 will wrap around again. That I get. But what I don't get is how to scroll the attribute table wraps around as well. From what I've read online, the 16x16 blocks it assigns attributes for will cause color distortions on the edge tiles of the screen (as seen when you scroll left to right and vice-versa in SMB3). The concern I have is that I understand how to scroll the nametables, but how do you scroll the attribute table? For intsance, if I have a green block on the left side of the screen, moving the screen to right should in theory cause the tiles to the right to be green as well until they move more into frame, to which they'll revert to their normal colors.

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  • bridge methods explaination

    - by xdevel2000
    If I do an override of a clone method the compiler create a bridge method to guarantee a correct polymorphism: class Point { Point() { } protected Point clone() throws CloneNotSupportedException { return this; // not good only for example!!! } protected volatile Object clone() throws CloneNotSupportedException { return clone(); } } so when is invoked the clone method the bridge method is invoked and inside it is invoked the correct clone method. But my question is when into the bridge method is called return clone() how do the VM to say that it must invoke Point clone() and not itself again???

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  • Deduce non-type template parameter

    - by pezcode
    Is it possible to deduce a non-type template parameter from a template function parameter? Consider this simple template: template <int N> constexpr int factorial() { return N * factorial<N - 1>(); } template <> constexpr int factorial<0>() { return 1; } template <> constexpr int factorial<1>() { return 1; } I would like to be able to change factorial so that I can alternatively call it like this: factorial(5); and let the compiler figure out the value of N at compile time. Is this possible? Maybe with some fancy C++11 addition?

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  • StructureMap - Injecting a dependency into a base class?

    - by David
    In my domain I have a handful of "processor" classes which hold the bulk of the business logic. Using StructureMap with default conventions, I inject repositories into those classes for their various IO (databases, file system, etc.). For example: public interface IHelloWorldProcessor { string HelloWorld(); } public class HelloWorldProcessor : IHelloWorldProcessor { private IDBRepository _dbRepository; public HelloWorldProcessor(IDBRepository dbRepository) { _dbRepository = dbrepository; } public string HelloWorld(){ return _dbRepository.GetHelloWorld(); } } Now, there are some repositories that I'd like to be available to all processors, so I made a base class like this: public class BaseProcessor { protected ICommonRepository _commonRepository; public BaseProcessor(ICommonRepository commonRepository) { _commonRepository = commonRepository; } } But when my other processors inherit from it, I get a compiler error on each one saying that there's no constructor for BaseProcessor which takes zero arguments. Is there a way to do what I'm trying to do here? That is, to have common dependencies injected into a base class that my other classes can use without having to write the injections into each one?

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  • Bulletin board - Database optimisation

    - by andrew
    This question is a follow on from this Question The project and problem The project I am currently working on is a bulletin board for a large non-profit organisation. The bulletin board will be used to allow inter-office communication within the organisation. I am building the application and have been having trouble extracting the results that I need from my database because I don't think it is properly normalized and because of limitations in my knowledge of relational database theory and mysql. I would appreciate input into the design of the board in general and in particular, ways that the database structure can be improved to facilitate efficient queries and help me develop this application and future application faster Business Logic The bulletin board will be used in the following way Posting bulletins and responses to bulletins Employees or 'users' in offices around the country will be able to post messages to the bulletin board.Bulletins must be posted to a location and categorised- i'll call these "bulletins". Users will be able to post any number of replies to any one bulletin and users will be able to reply to their own bulletin - i'll call these 'replies'. Rating bulletins and replies Users will be able to either 'like' or 'dislike' a bulletin or a reply and the total number of likes or dislikes will be shown for each bulletin or reply. Viewing the bulletin board and responses Bulletins can be displayed chronologically. Users can sort bulletins chronologically or chronologically by the latest reply to that bulletin(let me know if you need more explanation) When a particular bulletin is selected, replies to that bulletin will be displayed chronologically @PerformanceDBA - edited 10:34 est 28/12/10I have begun implementing the data model. I assume that the 6th data model is the physical model because it contains the associative tables. I am going to post any questions that I have below. I will put up a database dump once I am done. I will then put up a list of all the queries that I need to run on the database and begin writing them. I hope you had a good Christmas. I'm in Canada and there's snow! Implementation of Physical model

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  • Are returned locals automatically xvalues

    - by mark
    Following on from a comment I made on this: passing std::vector to constructor and move semantics Is the std::move necessary in the following code, to ensure that the returned value is a xvalue? std::vector<string> buildVector() { std::vector<string> local; // .... build a vector return std::move(local); } It is my understanding that this is required. I have often seen this used when returning a std::unique_ptr from a function, however GManNickG made the following comment: It is my understanding that in a return statement all local variables are automatically xvalues (expiring values) and will be moved, but I'm unsure if that only applies to the returned object itself. So OP should go ahead and put that in there until I'm more confident it shouldn't have to be. :) Can anyone clarify if the std::move is necessary? Is the behaviour compiler dependent?

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  • Force external function to be const

    - by vanna
    Here is my problem. I made a class with a member function declared as const that uses an external function that I cannot modify (declared in someone else's code) and that is not declared const. More precisely Someone else's code class B { public: void foo(); }; My code class A : public B { public: void bar() const { this->foo(); } }; I know that for member data we can force const-correctness by using mutable or const_cast. How can I 'hack' foo such that my compiler understands that I would like to use it as if it was const even if it is not declared in someone else's code ?

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  • Do you put a super() call a the beginning of your constructors?

    - by sleske
    This is a question about coding style and recommended practices: As explained in the answers to the question unnecessary to put super() in constructor?, if you write a constructor for a class that is supposed to use the default (no-arg) constructor from the superclass, you may call super() at the beginning of your constructor: public MyClass(int parm){ super(); // leaving this out makes no difference // do stuff... } but you can also omit the call; the compiler will in both cases act as if the super() call were there. So then, do you put the call into your constructors or not? On the one hand, one might argue that including the super() makes things more explicit. OTOH, I always dislike writing redundant code, so personally I tend to leave it out; I do however regularly see it in code from others. What are your experiences? Did you have problems with one or the other approach? Do you have coding guidelines which prescribe one approach?

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  • How to 'hide' spurious "declared but never used" warnings?

    - by Roddy
    I'm using the C++Builder compiler which has a minor bug that certain static const items from system header files can cause spurious "xyzzy is declared but never used" warnings. I'm trying to get my code 100% warning free, so want a way of masking these particular warnings (note - but not by simply turning off the warning!) Also, I can't modify the header files. I need a way of 'faking' the use of the items, preferably without even knowing their type. As an example, adding this function to my .cpp modules fixes warnings for these four items, but it seems a bit 'ad-hoc'. Is there a better and preferably self-documenting way of doing this? static int fakeUse() { return OneHour + OneMinute + OneSecond + OneMillisecond; }

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  • Warning as Error - How to rid these

    - by coffeeaddict
    I cannot figure out how to get rid of errors that basically should not be halting my compile in VS 2010 and should not be show stoppers, or at least I will fix them later but I don't want the compile to just error and halt on these kinds of problems. For example I'm getting the following error: Error 1 Warning as Error: XML comment on 'ScrewTurn.Wiki.SearchEngine.Relevance.Finalize(float)' has a paramref tag for 'IsFinalized', but there is no parameter by that name C:\www\Wiki\Screwturn3_0_2_509\SearchEngine\Relevance.cs 60 70 SearchEngine for this code: /// /// Normalizes the relevance after finalization. /// /// The normalization factor. /// If is false ( was not called). public void NormalizeAfterFinalization(float factor) { if(factor < 0) throw new ArgumentOutOfRangeException("factor", "Factor must be greater than or equal to zero"); if(!isFinalized) throw new InvalidOperationException("Normalization can be performed only after finalization"); value = value * factor; } I looked in Tools | Options and I don't see where I can tweak the compiler and tell it not to worry about comment or XHTML based errors.

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  • snprintf and Visual Studio 2010

    - by Andrew
    I'm unfortunate enough to be stuck using VS 2010 for a project, and noticed the following code still doesn't build using the non-standards compliant compiler: #include <stdio.h> #include <stdlib.h> int main (void) { char buffer[512]; snprintf(buffer, sizeof(buffer), "SomeString"); return 0; } (fails compilation with the error: C3861: 'snprintf': identifier not found) I remember this being the case way back with VS 2005 and am shocked to see it still hasn't been fixed. Does any one know if Microsoft has any plans to move their standard C libraries into the year 2010?

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  • Returning NSNull from actionForLayer:forKey

    - by MrHen
    If I implement the CALayer delegate method actionForLayer:forKey I can return [NSNull null] to force the CALayer to not animate any changes. Unfortunately, [NSNull null] doesn't implement the CAAction delegate and XCode kicks out the following warning: warning: class 'NSNull' does not implement the 'CAAction' protocol Here is the method code: - (id<CAAction>)actionForLayer:(CALayer *)theLayer forKey:(NSString *)theKey { //This disables the animations when moving things around //Also, don't animate the selection box. It was doing weird things if(undoGroupStarted || theLayer == self.selectionBox) { return [NSNull null]; } else { return nil; } } Am I doing something wrong? Is returning [NSNull null] bad behavior? If so, what is another way to do what I am trying to do here? If not, how do I make the compiler happy?

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  • remote function with pthread

    - by user311130
    Hi all, I wrote some code in c, using pthread (I configured the linker and compiler in eclipse IDE first). #include <pthread.h> #include "starter.h" #include "UI.h" Page* MM; Page* Disk; PCB* all_pcb_array; void* display_prompt(void *id){ printf("Hello111\n"); return NULL; } int main(int argc, char** argv) { printf("Hello\n"); pthread_t *thread = (pthread_t*) malloc (sizeof(pthread_t)); pthread_create(thread, NULL, display_prompt, NULL); printf("Hello\n"); return 1; } that works fine. However, when I move display_prompt to UI.h no "Hello111 " output is printed. anyone know how to solve that? Elad

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  • VB.Net List.Find. Pass values to predicate

    - by Beta033
    Having a bit of trouble using the List.Find with a custom predicate i have a function that does this private function test () Dim test As Integer = keys.Find(AddressOf FindByOldKeyAndName).NewKey here's the function for the predicate Private Shared Function FindByOldKeyAndName(ByVal k As KeyObj) As Boolean If k.OldKey = currentKey.OldKey And k.KeyName = currentKey.KeyName Then Return True Else Return False End If End Function by doing it this way means i have to have a shared "currentKey" object in the class, and i know there has to be a way to pass in the values i'm interested in of CurrentKey (namely, keyname, and oldkey) ideally i'd like to call it by something like keys.Find(AddressOf FindByOldKeyAndName(Name,OldVal)) however when i do this i get compiler errors. How do i call this method and pass in the values?

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  • How to make Visual C++ 9 not emit code that is actually never called?

    - by sharptooth
    My native C++ COM component uses ATL. In DllRegisterServer() I call CComModule::RegisterServer(): STDAPI DllRegisterServer() { return _Module.RegisterServer(FALSE); // <<< notice FALSE here } FALSE is passed to indicate to not register the type library. ATL is available as sources, so I in fact compile the implementation of CComModule::RegisterServer(). Somewhere down the call stack there's an if statement: if( doRegisterTypeLibrary ) { //<< FALSE goes here // do some stuff, then call RegisterTypeLib() } The compiler sees all of the above code and so it can see that in fact the if condition is always false, yet when I inspect the linker progress messages I see that the reference to RegisterTypeLib() is still there, so the if statement is not eliminated. Can I make Visual C++ 9 perform better static analysis and actually see that some code is never called and not emit that code?

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  • Compile-time trigonometry in C

    - by lhahne
    I currently have code that looks like while (very_long_loop) { ... y1 = getSomeValue(); ... x1 = y1*cos(PI/2); x2 = y2*cos(SOME_CONSTANT); ... outputValues(x1, x2, ...); } the obvious optimization would be to compute the cosines ahead-of-time. I could do this by filling an array with the values but I was wondering would it be possible to make the compiler compute these at compile-time?

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  • Succinct code over verbose?

    - by WeNeedAnswers
    With C# becoming more and more declarative and becoming the new Swiss army knife of Programming. Is it better to be succinct thus reducing the actual code base, or long winded but verbose. Is there a performance issue with succinct or does being succinct improve performance because your putting more of your code in the hands of the compiler. (LINQ being an example when used correctly). I know that verbosity should override succinct where code would become less readable, but is this a good idea when your style could affect the performance.

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  • Should I bundle C libraries with my Python application?

    - by oceanhug
    If I have a Python package that depends on some C libraries (like say the Gnu Scientific Library (GSL) for numerical computations), is it a good idea to bundle the library with my code? I'd like to make my package as easy to install as possible for users and I don't want them to have to download C libraries by hand and supply include-paths. Also I could always ensure that the version of the library that I ship is compatible with my code. However, is it possible that there are clashes if the user has the library installed already, or ar there any other reasons why I shouldn't do this? I know that I can make it easier for users by just providing a binary distribution, but I'd like to avoid having to maintain binary distributions for all possible OSs. So, I'd like to stick to a source distribution, but for the user (who proudly owns a C compiler) installation should be as easy as python setup.py install.

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  • Custom class object in Initialization list

    - by Michael
    I have a class Bar: class Bar { public: Bar(void); ~Bar(void); }; And a class Foo that gets a reference to Bar object as a constructor parameter and needs to save it in a private member bar_ : class Foo { private: Bar& bar_; public: Foo(Bar& bar) : bar_(bar) {} ~Foo(void) {} }; This doesn't compile : overloaded member function not found in 'Parser' missing type specifier - int assumed. Note: C++ does not support default-int Now i suspect couple of things that i need to assure, the second error is for Bar& bar_; declaration in Foo. Do i need to use an explicit constructor when declaring bar_ ? I am interested in learning how the compiler works regarding this matter, so a detailed explanation would be highly appreciated. Thanks.

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