Re: [boost] [TTI] Review for The Type Traits Introspection library by Edward Diener **extended**

Subject: Re: [boost] [TTI] Review for The Type Traits Introspection library by Edward Diener **extended**
From: Jeffrey Lee Hellrung, Jr. (jeffrey.hellrung_at_[hidden])
Date: 2011-07-17 19:02:53

On Sun, Jul 17, 2011 at 3:18 PM, Edward Diener <eldiener_at_[hidden]>wrote:

> On 7/17/2011 4:15 PM, Jeffrey Lee Hellrung, Jr. wrote:
>
>> On Sun, Jul 17, 2011 at 12:35 PM, Edward Diener<eldiener_at_[hidden]
>> >wrote:
>>
>>> On 7/17/2011 2:22 PM, Jeffrey Lee Hellrung, Jr. wrote:
>>>
>>>> Looks like it would be a simple matter of dispatching on
>>>>> is_member_function_pointer, is_function, and is_member_object_pointer
>>>>> from
>>>>> Boost.TypeTraits.
>>>>>
>>>>
>>>> It is little more complicated than that. The second parameter ( the
>>>> first
>>>> is the enclosing type ) in the non-composite form is the return type. A
>>>> return type could be a member function pointer itself etc., right ?
>>>>
>>>
>>> I think you can dispatch based on
>>> (a) the first template parameter is a member function pointer (or member
>>> data pointer for MEMBER_DATA)
>>>
>>
> This means switching the first two parameters when specifying the composite
> syntax. I am not comfortable with that only because the library regularizes
> on the notion that the first template parameter is the enclosing type.
> Otherwise your idea below will work.
>

Whoops, I had understood the composite syntax to allow you to do

has_member_function_xxx< Result (T::*)( Arg0, Arg1 ) >

but I see from the documentation of HAS_COMP_MEMBER_FUNCTION that it isn't
the case.  So why not support the above syntax instead?  I don't see the
point in specifying the enclosing class type twice.  To reiterate what I had
above, I propose the following to all be equivalent:

has_member_function_xxx< Result (T::*)( Arg0, Arg1 ) >
has_member_function_xxx< T, Result ( Arg0, Arg1 ) > // my personal
preference, probably
has_member_function_xxx< T, Result, boost::mpl::vector2< Arg0, Arg1 > >

By the way, how do you check for const member functions?  I don't remember
seeing anything about this in the documentation.  I would assume something
like

has_member_function_xxx< Result (T::*)( Arg0, Arg1 ) const >
has_member_function_xxx< T const, Result ( Arg0, Arg1 ) >
has_member_function_xxx< T const, Result, boost::mpl::vector2< Arg0, Arg1 >
>

would be most natural...???

- Jeff