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restricting template types?

Started by VI2 Aug 23, 2006 at 12:43 AM 3 replies 400+ views

Original Post

Aug 23, 2006 at 12:43 AM

Hello, I have a question regarding templates. Is it possible to restrict the types used in tempalate classes? IE I want a function: template getMyObject() { ... return (T)myObject }; myObject is stored as a base type, and I want it to be cast to my type T. But I need to make sure that the cast won't fail... Is there a way to limit the arguments into the tempalte type or is this better to do some kind of dynamic_cast checking?

deathkrush

Aug 23, 2006 at 12:57 AM

There is no way for the compiler to know the run-time type of myObject. The only way to do this would be to use the dynamic cast operator or implement some sort of type ID system.

DaBono

Aug 23, 2006 at 1:51 AM

Have a look here:
http://www.gamedev.net/community/forums/topic.asp?topic_id=407501&whichpage=1�
It contains some ideas to do this, using boost::type_traits and compile time assertions.

MaulingMonkey

Aug 23, 2006 at 2:00 AM

It already is limited. That code will fail to compile if you try to use a type that myObject is not convertable to. Any decent compiler will tell you that this is the cause as well, in an error message.

Fruny

Aug 23, 2006 at 2:08 AM

Note though that using a C cast is a Bad Idea if you're looking for help from the compiler. Use a static_cast, for Eris's sake!

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