Create generic classes to be specified later?

This is a discussion on Create generic classes to be specified later? within the C++ Programming forums, part of the General Programming Boards category; Yeah, I forgot I was working with std::string, I just didn't think about it because that wasn't my main problem, ...

  1. #16
    C++ Enthusiast jmd15's Avatar
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    Yeah, I forgot I was working with std::string, I just didn't think about it because that wasn't my main problem, but I appreciate you guys reminding me. Direct comparison is much easier and less bloated than the old C-style string way; bad habits from Win32 API programming mixed with C, bleh.

    Anyways, I wrote a virtual draw function in my base Sprite class, and now it works perfectly!

    pheres:
    That looks incredibly more efficient and EXACTLY what I was looking for, I was just about to ask if there was any other more efficient way than to compare each string like that. I hate repetitive programming as there are almost always better, faster, and slimmer ways to code it. Thanks a lot everybody, I'm off to check out std::map and then continue my project! woo!
    Trinity: "Neo... nobody has ever done this before."
    Neo: "That's why it's going to work."
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  2. #17
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    one way you could create the dictionary without using function pointers (I find code using function pointers to be very C-like, so personally I prefer to avoid them if there's an easy workaround) -

    Code:
    class ISpriteCreator  //Sprite Creator interface
    {
    public:
        virtual Sprite* Create(int int) = 0;
    };
    
    template<class ConcreteSprite>
    class SpriteCreator : public ISpriteCreator
    {
    public:
        Sprite* Create(int x, int y)
        {
            return new ConcreteSprite(x, y);
        }
    };
    
    // .. dictionary mapping strings to sprite creators
    
    std::map<std::string, ISpriteCreator*> dictionary;
    dictionary.insert( std::make_pair( "LeftCloud", new SpriteCreator<LeftCloud> () )  );
    Last edited by Bench82; 08-05-2007 at 09:03 AM.

  3. #18
    C++ Enthusiast jmd15's Avatar
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    Alright yeah, that looks good. I'll give that a try.
    But one other thing, when I did this:
    Code:
    SpriteFactory* factory = new ConcreteFactory();
    Sprite* test = factory->getSprite(0);
    ...
    test->draw();
    It worked perfectly. However, when I try ANY other value than 0 here (and yes, the numbers I tried are valid numbers for the sprite index) I get a segfault.
    Here's an example of what would give me a segfault.
    Code:
    SpriteFactory* factory = new ConcreteFactory();
    Sprite* test = factory->getSprite(1);
    ...
    test->draw();
    Any ideas on why this would happen?
    Thanks again!
    Trinity: "Neo... nobody has ever done this before."
    Neo: "That's why it's going to work."
    c9915ec6c1f3b876ddf38514adbb94f0

  4. #19
    C++ Enthusiast jmd15's Avatar
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    Cancel that, I know why I got a segfault.
    I'm going to go put that std::map in to get rid of those repetitive if statements, thanks a bunch to everyone, you helped me a great deal
    Trinity: "Neo... nobody has ever done this before."
    Neo: "That's why it's going to work."
    c9915ec6c1f3b876ddf38514adbb94f0

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