Template class forward declaration

Question

I am forward declaring a template outer and inner class as follows

template<class T>
class outer;

class inner;

Just after the above declaration I have a boost::serialization declaration defined as

namespace boost
{
    namespace serialization
    {
         template<class Archive> 
         void serialize(Archive &ar, outer &var, ...) { }
    }

}

Outer is a template class and thus requires specification of template arguments. If I attempt to do so as follows

...
     void serialize(... outer<T> &var ... ) { }
...

this is an error as only one template declaration is allowed. What is the proper way to define such a forward declaration?

If im not wrong you should do: template template void serialize(Archive &ar, outer &var, ...) { }. i dont remember but i think you can also put the templates in one line: template — Ariel Pinchover, May 09 '13 at 11:52
@tomislav-maric I thought I needed to separate template declarations; I thought they were unique and should not be mixed. I will do what you are suggesting. Put up an answer and I will up-vote and mark. — Mushy, May 09 '13 at 14:52

score 2 · Accepted Answer · answered May 09 '13 at 19:19

2

Try using two template parameters:

namespace boost
{
    namespace serialization
    {
         template<class Archive, class T> 
         void serialize(Archive &ar, outer<T>& var, ...) { }
    }

}

answered May 09 '13 at 19:19

tmaric

5,347
4
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score 1 · Answer 2 · answered May 09 '13 at 16:24

1

I might have misunderstood, but can you not do this:

template <class Archive, typename T>
void serialize( Archive archive, out<T> &var, ... );

answered May 09 '13 at 16:24

RandyGaul

1,915
14
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Template class forward declaration

2 Answers2