On 10/18/05, Robert Kawulak <kawulak@student.agh.edu.pl> wrote:
Hi,
From: Peder Holt
The problem is double_c is not a function object type - it only defines operator value_type(). If it'd also define
value_type operator() () { return static_cast<value_type>(*this); }
The mpl numerical holder classes already define a conversion operator, converting the held number to some native type defined by value_type. Would it not be possible to modify your library to use the conversion operator in stead?
Actually, after thinking the problem over, I've came to a conclusion that it's not that bad idea :) I'll try to implement this, I think it may simplify some things.
To extract a runtime equivalent: boost::mpl::runtime_value<MinValGen::value_type>(MinValGen());
There's something I don't understand - what does the above line do? I can't see runtime_value having a constructor?
Sorry. Typo. Should be: boost::mpl::runtime_value<MinValGen::value_type>()(MinValGen());
Basically the same as: MinValGen::value_type(MinValGen()), except not all the types in mpl::math has a conversion operator (yet...)
Thanks for explanation. But could you tell what is runtime_value used for?
Some "numerical holder" classes (such as rational) have a rather complex function for extracting a runtime value. The functionality has therefore been moved to the meta-function runtime_value instead. The interface for mpl::math is still very dynamic, so it may be that this construct will disappear in the future. Regards, Peder
Best regards, Robert
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