template specializiation

Thomas Neumann tneumann@users.sourceforge.net
Thu Jul 7 13:42:00 GMT 2005


Hi,

I have a question concerning template specialization where gcc behaves 
different than other compilers. (I already asked this on 
comp.lang.c++.moderated, but got no response).

Is it possible to specialize just a member variable? (example code 
below). The C++ standard is a little bit vague on this or perhaps I just 
didn't get it. Existing C++ compilers seem to be undecided, gcc and 
Microsoft accept the sample code, while icc, Comeau and Borland reject it.

struct A {
     const A* a;
};

template <const char* c> struct B {
     static const A b;
};

extern const char c[1]="";
extern const char d[1]="";

template<> const A B<c>::b = {&B<d>::b};
template<> const A B<d>::b = {&B<c>::b};


I tend to think it is at least not allowed in this form (two
specialization referencing each other), at least icc gives a somewhat
convincing error message. Does anyone have an idea how to fix it? I want
to use template specialization to plug in information in a template
class, the different specializations need to reference each other. I do
not want to specialize the whole class, as most of it would be redundant.
Also I would like to add new specialization without changing header
files, which _seems_ to work using the approach shown above, but would
not work if I had to specialize the whole class.

Thomas



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