I don't know if that is feasable at all, but this is what I'd like to achieve : in a templated class I would like to be using the namespace of the template parameter.
eg.
template<class P>
class Foo
{
public:
Foo();
virtual ~Foo();
void doSomething(P&);
void doSomethingElse();
protected:
// There I'm hardcoding "namespace1" but that's what I'd like to
// be possibly dynamic
// (I'm assuming template parameter P = namespace1::Type)
void method1(namespace1::Type1&);
...
void methodN(namespace1::TypeN&);
}
// Again, supposing P == namespace1::Type then I want to be using namespace1
// everywhere in the implementation...
using namespace namespace1;
template<class P>
void Foo<P>::doSomething(P& parameter)
{
...
Type1 type1 = P.getType1(); // There namespace1::Type1 is returned !!
method1(type1);
...
}
template<class P>
void Foo<P>::doSomethingElse()
{
...
TypeN typen; // There I want to instanciate a namespace1::TypeN !!
...
}
...
Of course I don't want to specialize the template and provide a dedicated implementation for every possible P
value as well as I'd like to avoid passing all the types like Type1
and TypeN
as template parameters since I potentially have lots of them.
Is that possible ?
The project is C++3 based, any boost solution is welcome.
Update
Being the template parameter P
itself exactly like any TypeN
parameter, this could be the right approach :
template<typename NAMESPACE>
class Foo
{
typedef typename NAMESPACE::Parameter MyParameter;
typedef typename NAMESPACE::Type1 MyType1;
typedef typename NAMESPACE::Type1 MyTypeN;
...
}
Best Answer
Yes and No.
Yes it is possible to deduce secondary types from a primary one, generally using a trait system:
No, you cannot deduce a namespace, and thus cannot use it; but note how by using a local alias (
typedef ...
) within the class there is no need to.