Re: [Boost-users] Determine at compile time whether type has subtraction semantics?

Subject: Re: [Boost-users] Determine at compile time whether type has subtraction semantics?
From: Raymond Burkholder (ray_at_[hidden])
Date: 2011-02-21 11:59:21

> On 19/02/11 06:51, Frédéric Bron wrote:
> >> Is it possible to determine at compile-time if a type has subtraction
> >> semantics? E.g. in struct A<T>  I would like to decide at compile-time
not
> to
> >> execute&A::subtract in the register_fns method. Then the subtract
> method is
> >> not instantiated and there is no error.
> Is there any way to do use the type traits to conditionally compile some
> code using some brief syntax? I.e. it would be nice if something like
> the following worked:
> 

I think you are looking for something along the lines of what is suggested
"An Optimized Version of std::copy" in the type_traits examples.
http://www.boost.org/doc/libs/1_45_0/libs/type_traits/doc/html/boost_typetra
its/examples/copy.html

It provides conditional compilation via a form of template
indirection/selection.

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