Re: [boost] Re: in/out parameters, codingstylesandmaintenance

From: Terje Slettebø (tslettebo_at_[hidden])
Date: 2003-05-03 23:37:05

>From: "Noel Yap" <Noel.Yap_at_[hidden]>

> "Justin M. Lewis" wrote:
> > A little bit of an overly simple example.  How about something more like
> >
> > Or, how about,
> > void GetFileName(c_in_out<std::string> path, const std::string &filter)
> > {
> >     std::string fname;
> >     FindFirstFileWithFilter(out(fname), path, filter);
> >     path += "/";
> >     path += fname;
> > }
>
> void GetFileName( ref< std::string > path, std::string const& filter )
> {
>   .
>   .
>   .
> }
>
> I believe returning a string may be more optimal than passing in an out
> parameter since:
> - the compiler can optimize away constructor/destructor calls with RVO.
> For example:
>
>   std::string cwd( MyGetCWD() );

I'd love to agree with you on this, but in the case of GetFileName(), where
you're passing in a string, and returning the same string modified, it can't
optimise away the returned string with RVO. In this case, an alternative is
to just say no to a function like this. :) For example by returning the
result, instead, as Joel and others have suggested.

Regards,

Terje