functions address

This is a discussion on functions address within the C++ Programming forums, part of the General Programming Boards category; I have this: Code: bool cmpItem (Item fst, Item snd) { ... } class Item { ... }; class Character ...

  1. #1
    Registered User C_ntua's Avatar
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    functions address

    I have this:
    Code:
    bool cmpItem (Item fst, Item snd) {
        ...
    }
    
    class Item {
        ...
    };
    
    class Character {
        ...
        list<Item> items;
        void addItem(Item item) {
            ...
            items.sort(cmpItem);
        }
    };
    which works fine. But just for organizing better my code, I would like cmpItem do be inside the Item class. But then the code "items.sort(cmpItem)" doesn't compile, since cmpItem is probably at the wrong scope. Is there a way to do this?

  2. #2
    Kernel hacker
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    You either need to make CmpItem a static function (which is probabky what you want if you want to pass it to something that takes a generic function pointer), or you need to use the "class-member function pointer", as described here. http://www.parashift.com/c++-faq-lit...o-members.html

    Most fo the time when you think you need a pointer-to-member-function, it's probably better to solve the problem with deriving different variants of the class, instead of using pointers. There are exceptions to this rule, but most of the time it's true.

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  3. #3
    C++まいる!Cをこわせ!
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    Btw, addItem should probably take a reference, not by-value.
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    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

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  4. #4
    Registered User C_ntua's Avatar
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    Quote Originally Posted by Elysia View Post
    Btw, addItem should probably take a reference, not by-value.
    I don't change the item, just add it to the list. But now that you mention it, it should be const.

    I knew the static keyword was useful :P (first time using it)

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