[boost] Re: Proposal for 'is_dereferenceable' and other templatemetafunctions

From: Alex Chovanec (achovane_at_[hidden])
Date: 2004-09-10 20:11:17

David Abrahams" <dave_at_[hidden]> wrote in message
news:ullfibawd.fsf_at_boost-consulting.com...
>
> Don't you think it's time we generalized the hack into a nice macro
> that generates the right code?
>

Agreed. That way we could have utilities like these to check for all unary
operators. In fact, I don't see any reason why the same idea couldn't be
applied to binary operators. I would think that the usage would look
something like this:

    DEFINE_UNARY_OPERATOR_TEST(is_dereferenceable, *);
    DEFINE_BINARY_OPERATOR_TEST(is_addable, +);

Then you could do

    is_dereferenceable<T>

or

    is_addable<T1, T2>

where the latter expression is true if 't1 + t2' is well-formed, where 't1'
is an instance of 'T1 &' and 't2' is an instance of 'T2 &'.

Is this what you had in mind, or close to it?

-- 
Alex Chovanec
NIF and Engineering Division
Computing Applications and Research Department
Lawrence Livermore National Laboratory