Re: [boost] [review] string convert

Subject: Re: [boost] [review] string convert
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2011-05-09 10:21:02

Vicente BOTET wrote:
> De : "Vladimir Batov"
> > > From: "Stewart, Robert"
> > > ...
> > >> int i = boost::convert::to(str);
> > >
> > > That's good.
> >
> > How about we simplify the API down to just:
> >
> > T convert::to(S, boost::parameter-list);
>
> As Robert said, the name of a free function must be readable
> when introducing a using namespace. Or is convert a class?

I think to<int>("FF") is readable.

> > Then we specialize it for convert::result type so that
> >
> > convert::result convert::to>(S, boost::parameter-list);
>
> I don't see any inconvenient in introducing a special overload.

I presume you mean that such an overload could be convenient for someone like Vladimir and would not cause a problem for those preferring other approaches.

> I guess a user needs to call it as follows
>
> convert::result r = convert::to>(S, boost::parameter-list);

It's hard to say as that was munged.

> > // The predictable. Throws on failure
> > int i = convert::to("FF", (format_ = std::hex))
>
> Would this overload exist only when the source parameter is
> string? Sorry, but I don't see how it could be used for type-
> to-type conversions

If it supports type-to-type conversion via an I/O stream, it would apply, wouldn't it?

> int i = convert::to(aValue, (format_ = std::hex))
>
> Would the std::hex be applied to the output or the input
> stream?
>
> ios << aValue;
> ios >> std::hex >> i;
>
> or
>
> ios << std::hex << aValue;
> ios >> i;
>
> Are these equivalent?
>
> I think the interface must state clearly when these
> manipulators are applied.

I think it should be something like this:

convert::as<int>(aValue, (in_ = std::hex, out_ = std::hex));

> Vladimir, as I said you my library doesn't pretend to take care
> of string conversions or conversions via a stream.

I presume you mean string-to-string conversions when you write "string conversions" ...

> My library will specialize the convert_to function when one of
> the  parameters is a string and call the best library providing
> it.

...because of that.

_____
Rob Stewart                           robert.stewart_at_[hidden]
Software Engineer                     using std::disclaimer;
Dev Tools & Components
Susquehanna International Group, LLP  http://www.sig.com





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