Re: [boost] [Convert] std::isspace requires unsigned #28

Subject: Re: [boost] [Convert] std::isspace requires unsigned #28
From: Vladimir Batov (Vladimir.Batov_at_[hidden])
Date: 2017-03-21 00:26:25

On 2017-03-21 11:16, Vladimir Batov via Boost wrote:
> ...
> Damn confused.
> 
> WAS: std::isspace(ch);
> THEN: std::isspace(static_cast<unsigned char>(ch));
> 
> THEN I realized I needed wchar_t support and therefore needed also
> std::iswspace(). So, for such a seemingly trivial thing I ended up
> with the following ugliness:
> 
> namespace cnv
> {
>     template<typename char_type>
>     struct char_test {};
> 
>     template<>
>     struct char_test<char>
>     {
>         static bool is_space(char ch)
>         {
>             return std::isspace(static_cast<unsigned char>(ch));
>         }
>     };
>     template<>
>     struct char_test<wchar_t>
>     {
>         static bool is_space(wchar_t ch)
>         {
>             return std::iswspace(ch);
>         }
>     };
>     template<typename char_type>
>     bool
>     is_space(char_type ch)
>     {
>         return char_test<char_type>::is_space(ch);
>     }
> }
> 
> That raises two questions.
> 
> 1) Is it really the only way to go or I went senile or fell behind
> language-wise?
> 2) What about std::iswspace? Does it also need static_cast?

OK, I guess function specifications are much shorter. Phew. Still. What 
do I do with No.2?

template<typename char_type> bool is_space(char_type);

template<> bool is_space (unsigned char c)...
template<> bool is_space (char c)...
template<> bool is_space (unsigned wchar_t c)...
template<> bool is_space (wchar_t c)...