Define template parameter or just declare?

[jim]

Hi,

I want to do something like this:

foo.h:
class FooData;
typedef MyTemplate<FooData> MyFoo;

class Foo2: public MyFoo {
// ...
};

foo.cpp:
class FooData {
// ...
};

Assume that MyTemplate only uses pointers to its template parameter and
never calls any methods on it (just passes pointers to it to other
routines/classes). I seem to remember reading that this won't work,
because you always have to define (not just declare) a class before you
use it as a template parameter. Is this right?

Cheers,
Jim

 

[Ian Collins]

Hi,

I want to do something like this:

foo.h:
class FooData;
typedef MyTemplate<FooData> MyFoo;

class Foo2: public MyFoo {
// ...
};

foo.cpp:
class FooData {
// ...
};

Assume that MyTemplate only uses pointers to its template parameter and
never calls any methods on it (just passes pointers to it to other
routines/classes). I seem to remember reading that this won't work,
because you always have to define (not just declare) a class before you
use it as a template parameter. Is this right?

I don't think so, the class has to be in scope when the template is
instantiated.