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Quickly Check whether C++ Template Instances have the Same Parameters

, 9 Feb 2012 CPOL
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This post helps to quickly check whether C++ template instances have the same parameters.

Setting up a custom type identification mechanism only makes sense if RTTI is not available or you cannot guarantee that it is consistent. That might be the case on some platforms with dynamic libraries.

A simple static_cast will not work for all possible inheritance paths. Also, your method generates a different id in each translation unit ChildClass<t> is pulled into. I have yet to see a solution for "safe" class IDs mechanism fundamentally different from that used by COM.

So if you have RTTI, you just do this:

virtual bool equals(BaseClass *other) const
{
    if (auto temp = dynamic_cast<ChildClass<T>*>(other)) {
        //...
    }
}

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This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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paul michalik
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Comments and Discussions

 
GeneralIs this faster than my method? It is surely safer, but my go... PinmemberSebastian Krysmanski7-Feb-12 22:13 
GeneralRe: Faster? Probably not, a dynamic_cast can have considerable c... Pinmemberpaul_719-Feb-12 21:34 
Faster? Probably not, a dynamic_cast can have considerable cost with complex type hierarchies. But it is the only safe way to do that.
 
I also corrected some typos, it's hard to get through all the html tags...

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