Templated class method definition syntax

Question

Class definition:

template<class K, class V,
         unsigned hashFunc(const K&),
         int compFunc(const K&,const K&)=&_compFunc<K> > class X {};

I want to define a class method outside of the class code block. like so:

template<class K, class V,
         unsigned hashFunc(const K&),
         int compFunc(const K&,const K&)=&_compFunc<K> >
X<K, V, hashFunc, compFunc>::X() { }

g++ v.4.4.3 returns

error: default argument for template parameter for class enclosing ‘X::X()’

Why is the compiler complaining and how can i make it work?

Answer 1

You didn't declare or define a constructor for X. In addition, you had repeated the default template parameters in your attempted X::X definition.

Here's the fixed code, main-ified:

template<class K, class V,
         unsigned hashFunc(const K&),
         int compFunc(const K&,const K&)=&_compFunc<K> > 
class X 
{ 
    X();
};

template<class K, class V,
         unsigned hashFunc(const K&),
         int compFunc(const K&,const K&) >
X<K, V, hashFunc, compFunc>::X() { }

int main()
{
}