Re: [boost] wrong number of template arguments for "char_regex_traits_i"

From: John Maddock (john_at_[hidden])
Date: 2007-11-30 03:42:18

Barco You wrote:
> Hello ,
> I include <boost/regex.hpp> in my program, when compiling I got
> message:
>
> boost/regex/v4/char_regex_traits.hpp:34: error: wrong number of
> template arguments (1, should be 2).

I've never seen that before: what compiler/platform are you using?

> I checked the wrong line in boost/regex/v4/char_regex_traits.hpp ..
> template <calss charT>
> class char_regex_traits_i : public regex_traits<charT>{};
>
> template<>
> class char_regex_traits_i<char> : public regex_traits<char>
> {
> public:
>   typedef char char_type;
>   typedef unsigned char uchar_type;
>   typedef unsigned int size_type;
>   typedef regex_traits<char> base_type;
>
> };
>
> and then I checked the template regex_traits defined in
> boost/regex/v4/regex_traits.hpp:
>
> template <class charT, class implementationT >
> struct regex_traits : public implementationT
> {
>   regex_traits() : implementationT() {}
> };
>
> It's really a but, do you thinks so?
>
> what should the implementationT be for char_regex_traits_i    in
> boost/regex/v4/char_regex_traits.hpp?

The second template argument to regex_traits is defaulted in regex_fwd.hpp:

#ifdef BOOST_REGEX_USE_WIN32_LOCALE
template <class charT, class implementationT = w32_regex_traits<charT> >
struct regex_traits;
#elif defined(BOOST_REGEX_USE_CPP_LOCALE)
template <class charT, class implementationT = cpp_regex_traits<charT> >
struct regex_traits;
#else
template <class charT, class implementationT = c_regex_traits<charT> >
struct regex_traits;
#endif

But you shouldn't need to know that: the second argument is an 
implementation detail.

Regards, John.