Re: [boost] generating unique ordinal value at compile time

5 Mar 2007


      Andrey Semashev <andysem <at> mail.ru> writes:
...
Just a thought... Maybe something like this might help:
typedef [implementation defined] uint_ptr_t;
template< typename >
void foo() {}
template< typename T, uint_ptr_t TagV = (uint_ptr_t)&foo< T > >
struct ordinal : public mpl::integral_c< uint_ptr_t, TagV >
{
};
struct system1 : ordinal< system1 > {};
struct system2 : ordinal< system2 > {};
The uint_ptr_t type should be large enough to accomodate a pointer to
function. It is needed since function pointers cannot be ordered.
I suspect, not all compilers would allow this.
No compiler should allow it.  (uint_ptr_t)&foo< T >
is not a valid template argument.  The address of
foo<T> is not known until link time or later.

In Christ,
Steven Watanabe