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

From: David Abrahams (dave_at_[hidden])
Date: 2004-09-12 10:40:16

Daniel Wallin <dalwan01_at_[hidden]> writes:

> David Abrahams wrote:
>> Daniel Wallin <dalwan01_at_[hidden]> writes:
>> 
>>>David Abrahams wrote:
>>>
>>>>Daniel Wallin <dalwan01_at_[hidden]> writes:
>>>>
>>>>>I have been toying with a more general solution to this problem, where
>>>>>one can do things like:
>>>>>
>>>>>  check_dereference<T, is_convertible<mpl::_, U&> >
>>>>>  check_add<T, T, is_convertible<mpl::_, T> >
>>>>>
>>>>> etc. 
>>>>
>>>>That *might* be impressive if I could tell what those expressions
>>>>were
>>>>supposed to mean ;-)
>>>
>>> The metafunction class 
>> I don't see a metafunction class here.  Don't you mean "lambda
>> expression?"
>
> Maybe. I was trying to describe the formal argument. So I guess
> something like:
>
>    template<class T, class U, class Predicate>
>    struct check_add;
>
>      Where Predicate is a unary metafunction class or a lambda
>      expression.
>
> ??

The new definition of "lambda expression" is:

    a metafunction class -or- a placeholder expression

so, you can just say "unary lambda expression."

> [snip]
>> Oh, very nice!  Now it's impressive. :-)
>
> :) So, anyone interested in this?

Yeah, sure, I'm interested.  I still hope whoever's doing this won't
overlook free functions like swap ;-).

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com