Alias for class template

This is a discussion on Alias for class template within the C++ Programming forums, part of the General Programming Boards category; Unfortunately, it's illegal to make a typedef for an incomplete type, like: Code: typedef std::vector MyVector; // Illegal! Is there ...

  1. #1

    Join Date
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    Alias for class template

    Unfortunately, it's illegal to make a typedef for an incomplete type, like:
    Code:
    typedef std::vector MyVector; // Illegal!
    Is there any kind of workaround for this without having to use macros?

  2. #2
    The larch
    Join Date
    May 2006
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    I think this might become possible in C++0x.

    But in this particular example, why would it be useful?
    I might be wrong.

    Thank you, anon. You sure know how to recognize different types of trees from quite a long way away.
    Quoted more than 1000 times (I hope).

  3. #3

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    I have a class template with two parameters, the second of which is a template template parameter:
    Code:
    template <typename T, template <typename> class T2>
    class Object
    {
        friend class Object <T, ?>;
    };
    The second template parameter can only be one of two types, and I want any class Object <T, FirstPossibleType> to be friends with the class Object <T, SecondPossibleType> and vice versa.

    Template metaprogramming would normally allow this to be possible, except the second parameter is a template template parameter and cannot be typedef'd. (None of this would be an issue if friend class declarations could be templated...)
    Last edited by rudyman; 07-26-2008 at 05:12 PM. Reason: Typo

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