Re: [boost] [Spirit] Using real_parser with user-definednumerictypes

From: Joel de Guzman (joel_at_[hidden])
Date: 2007-10-31 02:36:58

John Maddock wrote:
> Hartmut Kaiser wrote:
>> John,
>>
>>>> I'll look into this later tonight.
>>> Thanks Harmut: if you need a simple user-defined number type
>>> to experiment with then try
>>> boost::math::concepts::real_concept in
>>> boost/math/concepts/real_concept.hpp.
>> Ok, I tried that and fixed the pow() issue first (it's in SVN now).
>> After this change the code compiled, but as you pointed out the
>> actual parsing fails. The reason is that
>> std::numeric_limits<boost::math::concepts::real_concept>::max() always
>> returns zero, which triggers the overflow detection in the spirit
>> real_parser, making the overall parse fail.
>>
>> I didn't investigate the numeric_limits::max issue, though.
>> Do you have any ideas?
> 
> Ah, numeric_limits is deliberately not specialised for the real_concept 
> type, because I wanted to work with types that vary precision at runtime, 
> and numeric_limits just can't cope with that :-(
> 

Ok, Hartmut briefed me with this sometime this morning. It *is* indeed a
bug with Spirit that's already been addressed in Spirit2. I'll see if I
can patch Spirit1 code to follow the Spirit2 behavior. Do you need
something immediately? Will a few days wait for a patch ok?

Regards,
-- 
Joel de Guzman
http://www.boost-consulting.com
http://spirit.sf.net