Subject: Re: [boost] Boost.Convert+Boost.Parameter
From: Hartmut Kaiser (hartmut.kaiser_at_[hidden])
Date: 2009-02-28 12:17:41
> the Boost.Range library introduce the concept of adaptor (or view). I'm
> wondering if this could be also convenient for the Boost.Convert
> Take the uuid user data type.
> uuid u;
> string res;
> u | corverted_to<string> | uppercased > res;
> The evaluation should be lazy, only when we assign throwg the >
> operator we force the evaluation.
> string str;
> int i = str | radix(10) | locale(...) | converted_to<int>;
> Could this approach work for the Boost.Convert library?
Well, in this case I really prefer:
using namespace spirit::std_locale;
spirit::qi::parse(str, spirit::int_, i);
or, if you need another radix:
typedef spirit::qi::int_parser<int, 16> hex;
spirit::qi::parse(str, hex(), i);
or, if you need exactly 4 hex digits:
typedef spirit::qi::int_parser<int, 16, 4, 4> hex4;
spirit::qi::parse(str, hex4(), i);
Which is far less convoluted.
Same/similar works for converting the other way around:
typedef spirit::karma::int_generator<int, 16> hex;
spirit::karma::generate(std::back_inserter(str), hex(), i);
I still don't get it. I agree that it might be favorable to have a simple
API for type<-->string conversions.
But as you can clearly see the requirements are piling up and it's
everything else but simple by now.
So I ask again:
What's the benefit of coming up with just another full blown
parser/generator interface in Boost?
What's the benefit of discarding/obsoleting lexical_cast<>() as the _really_
minimal, simple interface?
Guy's. You're trying to come up with a DSEL (domain specific embedded
language) for parsing and generating.
What's it exactly you don't like in Spirits DSEL? Just the fact that it
wasn't _you_ to come up with this particular syntax? Have you even looked?
Wouldn't it be better to use the experience the Spirit developers/users have
collected over _years_ (!) and try to find a simpler API on top of Spirit
directly extending from the existing one, certainly while limiting the
possibilities in favor of a reduced feature set and a simplified usage
Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk