Template metaprogramming forward declaration

[steprobe]

Hi guys,
If I have a class like the following:

template<int Degree>
class MegaClass
{
.....
};

And then I have another class in a seperate header file, myheader.h:

class AnotherClass
{
private:
MegaClass<2> theClass;
};

What is the syntax to forward declare MegaClass<2> in myheader.h? I have
tried a few different ways, none of which have worked, and I couldn't
find anything on google.

Thanks,
Stephen

 

[Alf P. Steinbach]

* steprobe:

If I have a class like the following:

template<int Degree>
class MegaClass
{
.....
};

And then I have another class in a seperate header file, myheader.h:

class AnotherClass
{
private:
MegaClass<2> theClass;
};

What is the syntax to forward declare MegaClass<2> in myheader.h? I have
tried a few different ways, none of which have worked, and I couldn't
find anything on google.

Since you have a MegaClass<2> data member a forward declaration isn't enough.
For a declaration of a data member of type T, sizeof(T) must be well-defined.
So, just #include the header that defines the class template.


Cheers & hth.,

- Alf

 

[steprobe]

Since you have a MegaClass<2> data member a forward declaration isn't
enough. For a declaration of a data member of type T, sizeof(T) must be
well-defined. So, just #include the header that defines the class template.

Yes, of course. My mistake. If I change that member to a pointer how
might I forward declare it?

 

[Vladimir Jovic]

Yes, of course. My mistake. If I change that member to a pointer how
might I forward declare it?

Like this:

template< int Degree >
class MegaClass;