On Sun, 10 Aug 2003 03:33:50 -0400, "Eric Friedman"
<[EMAIL PROTECTED]> wrote:
>Dave (and others):
>
>Eric Friedman wrote:
>> David Abrahams wrote:
>> >
>> > Hi,
>> >
>> > BOOST_EXPLICIT_TEMPLATE_TYPE is great!
>> >
>> > However:
>> [snip]
>> > // specialization
>> > template <>
>> > int f<void>( /*what goes here?*/ )
>> > {
>> >
>> > }
>> >
>> > we have no mechanism for handling these. Any ideas?
>>
>> Wouldn't BOOST_EXPLICIT_TEMPLATE_TYPE(void) work?
>
>Ooops, you're right. Guess I don't know the standard well enough.
>
>I've added BOOST_EXPLICIT_TEMPLATE_TYPE_SPEC (and so on) helper macros to
>address this problem (in config/suffix.hpp) since it's actually been
>creating problems with variant under gcc. Let me know if this solution
>doesn't meet your expectations.
It may help to paste here what I said to Dave in the first place (he
wrote privately too, and since I wasn't following the list I didn't
notice that a copy was also posted here):
--------------
> However:
>
> template <class T>
> int f(BOOST_EXPLICIT_TEMPLATE_TYPE(T))
> {
> ...
> }
>
> // specialization
> template <>
> int f<void>( /*what goes here?*/ )
> {
>
> }
>
> we have no mechanism for handling these. Any ideas?
Hmm... no, because then you clash with other VC6 bugs (concerning
default arguments).
Of course you can't put BOOST_EXPLICIT_TEMPLATE_TYPE(void) because it
re-defaults the dummy argument (which is illegal) but even without the
default... :-( For instance:
template <class T>
int f( boost::type<T>* = 0 )
{
return 0;
}
// specialization
template <>
int f( boost::type<void> * )
{
return 1;
}
int main()
{
std::cout << f<int>() << '\n';
std::cout << f<void>() << '\n';
return 0;
}
VC6 says "error C2660: 'f' : function does not take 0 parameters" at
the line that contains the call to f<void>.
----------------------
Genny.
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