Re: limiting a template class to certain types ?
mast2as@yahoo.com wrote:
Is it possible to limit a template class to certain types only. I
found a few things on the net but nothing seems to apply at compile
time.
template <typename T>
class AClass
{
public:
AClass() {}
};
AClass<float> floatSomethng; // yes it's fine
AClass<int> intSomething; // no we don't want to allow the creation of
that object
The simplest way is probably hide the implementation of your template
type in a separate translation unit and use explicit instantiations
to stuff the same TU with the implementations of the class for some
specific types. A better way would be to design it so there is no
need to limit it.
Or you could do something like this (AKA "type traits"):
template<class T> class allowed { enum { yes }; };
// then specialise it for the types that you allow:
template<> class allowed<float> { public: enum { yes = 1 }; };
template<> class allowed<double> { public: enum { yes = 1 }; };
// and last, use it:
template<typename T>
class AClass
{
static const bool allowed = allowed<T>::yes;
public:
AClass() {}
};
int main() {
AClass<float> af;
AClass<int> af; // error
}
V
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