Thread: compiletime test for inheritance between classes

  1. #1
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    compiletime test for inheritance between classes

    a while back, a guy i worked with came up with a really cool bit of code; it would tell you if one class inherited from another, and this test was done at compile time.

    it was used like this:

    Inheritance<Base,Derived>::exists

    i could really use it now, but i don't have his code and i don't know how he did it. any ideas?

  2. #2
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    it probably used dynamic_cast. it could be done like this at runtime:

    Code:
    template<typename Base, typename Derived>
    bool InheritanceExists()
    {
      Derived* derived;
      return dynamic_cast<Base*>(derived);
    }

  3. #3
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    actually it didn't. it was a pure compile-time operation. i just found it. it's on p34 of alexandrescu's modern c++.

  4. #4
    C++まいる!Cをこわせ!
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    Boost has some interesting meta template stuff.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

  5. #5
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    definitely not worth pulling in boost over. the implementation is trivial, actually.

    it just so happens this is in the book preview:

    Modern C++ design: generic programming and design patterns applied - Andrei Alexandrescu - Google Books

  6. #6
    C++まいる!Cをこわせ!
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    Boost has a lot of other goodies, too. Boost is always worth having.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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