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Subject: Re: [boost] Numeric constants
From: Phil Endecott (spam_from_boost_dev_at_[hidden])
Date: 2009-01-30 12:12:48

John Maddock wrote:
>>> template <class T> T pi();
>> I have a fixed-point class. What actually happens when I call
>> pi<fixed>() ?

> Currently with Boost.Math if you call:
> pi<my_UDT>()
> then internally it does a lexical_cast from a string containing ~100 decimal
> digits to my_UDT.

OK, I suppose that makes sense in general. My fixed class doesn't have
operator<<,>> unfortunately, since I've never needed them for anything else.

> And finally don't forget that you could add
> user-defined full specialisations of the templates for my_UDT if my_UDT
> provides its own interfaces to various constants.

Can I specialise all_constants<my_type> to cast from double without
having to write out all of the constants individually?


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