Re: [boost] Re: Macro for using overloaded functions with templated code.

From: Jonathan Wakely (cow_at_[hidden])
Date: 2004-11-19 05:12:16

On Thu, Nov 18, 2004 at 10:35:08PM +0000, Daniel James wrote:

> Jonathan Wakely wrote:
> >Could you supply an extra arg to the macro, specifying whether to define
> >the nullary overload for the cases where it is wanted and valid ?
> 
> Yep, or maybe minimum, maximum parameter arguments. Although, if the 
> macro gets complex enough to invoke, it'll probably be better just to 
> write it out manually. For example, your tolower test becomes:
> 
>     #include <string>
>     #include <algorithm>
>     #include <cctype>
> 
>     struct {
>         template <class T>
>         T operator()(T x) { return std::tolower(x); }
>     } tolower_visitor;
> 
>     int main()
>     {
>         std::string s("FNORD");
>         std::transform(s.begin(), s.end(), s.begin(),
>             tolower_visitor);
>     }
> 
> Which is perhaps better since it has the correct return type.

Indeed. It was the chance to avoid exactly that wrapper functor that
interested me in your macro - but as you say, if the macro ends up
taking many arguments it's simpler to explicitly define the functor.

regards,

jon

-- 
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