Re: Problem with deriving from stream templates

[Bernd Strieder]

Hello,

Dan Smithers wrote:

> I want to write my own class derived from the ostream class.
> 
> I have been getting errors with my templates:
> 
> First, I get an error writing a nested template. If I leave the
> function definition inside template class definition (commented out at
> //1) then it compiles and runs fine, but if I declare and define the
> function separately (at //2).
> 
> Is the following syntax supported by g++?
> template<typename charT, typename Traits>
> template<typename T>
> as I get the compiler error
> "mystream.cpp:47: error: too many template-parameter-lists"

You have to declare the function you intend to become a friend before
the template class. Since the template class itself is in the
interface of that function, you habe to forward declare the template
class.

template <typename charT, typename Traits=std::char_traits<charT> >
class CMyStream;

template <typename charT,
          typename Traits = std::char_traits<charT> ,
          typename T>
CMyStream<charT, Traits>& operator<<(CMyStream<charT, Traits>& ostr,
                                     T val);

This problem is a gcc-ism only as far as gcc started to be more
strict along the lines of the standard. You'd better ask in some
general newsgroup like comp.lang.c++(.moderated), or even their 
FAQs.

Can't help on the other problems now.

Bernd Strieder