Re: [boost] Re: lexical_cast "Future directions"

From: Terje Slettebø (tslettebo_at_[hidden])
Date: 2002-12-30 17:54:59

>From: "Thomas Witt" <witt_at_[hidden]>

> Kevlin Henney wrote:
> >>
> >>This is the philosophy that Kevlin and I agreed on when lexical_cast
> >>was first introduced.  However, I don't think it has stood the test of
> >>time with real users, and it would be stupid to ignore that.  I
>
> Agreed. I see the problem, I am just unsure with regard to the solution.
>
> >>suspect Kevlin feels the same way about it, which is why he has agreed
> >>to review the changes in the Files area.
> >
> > Apologies for delays. Yes, I have to review Terje's changes and am
> > guilty of not having applied myself to that task yet. In terms of the
> > philosophy of the design, I think it would be reasonable to say that
> > intuitive stream-based conversion is the aim, which is compatible with
> > fixing whitespace issues.
>
> One more argument. lexical_cast may be able to provide intuitive
> conversion for all std string types, but it will likely brake again for
> custom string types. Even if the custom type has exactly the same
> interface and semantics as std::string lexical_cast will break.

Yes. That's why the proposal is designed to be _extensible_, to allow
conversions between arbitrary types. See e.g. this posting
(http://aspn.activestate.com/ASPN/Mail/Message/1403188). The interface will
likely change, from using "boost::detail::lexical_cast_impl" to
"boost::lexical_cast_traits", which will then perform the actual conversion.
This may then be specialised for new types, which will then be handled
seamlessly by lexical_cast, as shown in the mentioned posting.

> naggingly yours

<g> No, this is good stuff. :)

Regards,

Terje