Re: [boost] Boost.Conversion - pre review request

Subject: Re: [boost] Boost.Conversion - pre review request
From: Hartmut Kaiser (hartmut.kaiser_at_[hidden])
Date: 2011-07-09 10:37:17

> > On Jul 9, 2011, at 2:52 AM, Jeroen Habraken wrote:
> >> On 9 July 2011 04:10, Gordon Woodhull <gordon_at_[hidden]>
> wrote:
> >>> (Jeroen, if you're reading this, can you convert to/from e.g.
> >>> hexadecimal with Coerce?)
> >>
> >> It isn't possible at the moment but it is to be re-added during the
> >> Google Summer of Code. The syntax will probably look something like
> >> coerce::as<int>("0x17", tag::hex());
> >
> > Aha, that's why I asked.  Not currently compatible with
> Boost.Conversion:
> > just as there's no way to supply iostream manipulators for
> > Convert-style formatting, there's no way to supply tags for Coerce-
> style.
> >
> > Vicente, do you have any thoughts on whether extra parameters could be
> > added generically?
> 
> I don't think that these kind of specific conversions could be added to
> simple type-to-type conversions. As I signaled during the Boost.Convert
> review I will use instead an auxiliary string stream and output and input
> the types we want to convert using as many manipulators as the user wants.
> 
> I have added an example here
> http://svn.boost.org/svn/boost/sandbox/conversion/libs/conversion_ext/exam
> ple/formatted.cpp
> that shows how I will apply these kind of conversions. As you can see this
> example doesn't make use of the Boost.Conversion generic functions when
> manipulators are needed. Instead it uses either a template io stream
> (extractor_stream) that is able to extract the type given as parameter
> when the extract manipulator is used or a io stream ( via_stream) that is
> able to extract any type given as parameter of the manipulator extract_to.

This might be off topic and purely esthetical (i.e. personal taste), but I
find the mix of operator>>() and operator<<() in the same expression to be
more than confusing. That's (for me) clearly not a viable solution.

Regards Hartmut
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