[boost] [Pragram Options in particular]std::basic_string usage

From: Sean Huang (huangsean_at_[hidden])
Date: 2006-03-30 12:04:03

I noticed that a few boost libraries use std::basic_string differently. For 
example, boost::program_options uses it like this:
template<class T, class charT>
void validate(boost::any& v,
                    const std::vector< std::basic_string<charT> >& xs,
                    T*, long);
And string_algorithm uses the following instead:

template<
    typename SequenceT,
    typename CharT,
    typename RegexTraitsT,
    typename FormatStringTraitsT, typename FormatStringAllocatorT >
    inline void replace_all_regex(
                                                SequenceT& Input,
                                                const basic_regex<CharT, 
RegexTraitsT>& Rx,
                                                const 
std::basic_string<CharT, FormatStringTraitsT, FormatStringAllocatorT>& 
Format,
                                                match_flag_type 
Flags=match_default | format_default );
The standard says std::basic_string has 3 template parameters (two have 
defaults). Usages like std::basic_string<charT> would prevent the matching 
of non-standard traits or allocators. And in the case of program_options, my 
overload  with 3 template parameters actually caused an ambiguity with one 
defined in program_options:
My overload:
template< class CharType, class Traits, class Alloc >
void validate( boost::any& v,
                    const std::vector< std::basic_string< CharType, Traits, 
Alloc > >& xs,
                    unsigned long*, long )

Defined in program_options:
template<class T, class charT>
void validate(boost::any& v,
                    const std::vector< std::basic_string<charT> >& xs,
                    T*, long)

My question is if the differences in usage is justified or just an oversight 
and what the recommendation is?

Thanks,

Sean