// This gives errors:// 'invalid use of template-name ... without an argument list'template <class AA::A> template <class BB::B> Three<AA::A>::Three(const Three<BB::B> & other);template <> Three<AA::A>::Three(const Three<BB::B>&);Quote:Original post by Deyja
Second, If you're trying to specialize this constructor, it would look more like
Quote:Original post by ToohrVykQuote:Original post by Taldor
Sadly, this only works in this example and not in my actual code.
Erm. You're much more familiar with your own code than I am, so could you please say what the exact problem is in adapting this example to your code? The way I see it, you merely have to define a function which calls the appropriate constructor (something which should be possible if you ever intended to call that constructor in the first place);
Quote:Original post by Taldor
I was wrong, I don't think it works in the example either, as I'm (trying to) instantiate the copy constructor you use in the convert function, so wrapping it in a function won't help, I believe.
Quote:Original post by ToohrVyk
Using [foo] in a function will always instantiate [foo] if the function itself is instantiated at a point where the definition of [foo] is visible (that's the way template instantiation works). And so, by instantiating convert, I indirectly instantiate the constructor used inside.
template <class FROM, class TO> void convert (const FROM & from){ return (void) TO (from);}template void convert <Three <BB :: B <YY :: Y> >, Three <AA :: A <XX :: X> > > (const Three <BB :: B <YY :: Y> > & from);#include <iostream>// Definition without function bodies class One {};class Two : public One {};template <class T> class Three : public Two{public : Three (); template <class U> Three (const Three <U> &);};namespace AA{ class A {};}namespace BB{ template <class T> class B : public AA::A {};}class X {};// Calls int main(){ Three< BB::B<X> > bx; Three< AA::A > a (bx);}#include <iostream>// Definitions class One {};class Two : public One {};template <class T> class Three : public Two{public : Three () {} template <class U> Three (const Three <U> &) { std::cout << "Bar\n"; }};namespace AA{ class A {};}namespace BB{ template <class T> class B : public AA::A {};}class X {};// Instanciation template Three< BB::B<X> >::Three();template<class C1, class C2>void convert(const C2& o){ return (void) C1(o);}template void convert< Three<AA::A>, Three< BB::B<X> > >(const Three< BB::B<X> > &);
