Re: [boost] Bind comparisons

From: Peter Dimov (pdimov_at_[hidden])
Date: 2006-02-02 18:07:18

David Abrahams wrote:
> Peter Dimov <pdimov <at> mmltd.net> writes:
>
>> David Abrahams wrote:
>>> Is it really true that I can write
>>>
>>>   bind(f, _1) > _2
>>>
>>> but can't write
>>>
>>>    _1 > _2
>>>
>>> ??
>>
>> A limitation of the current implementation. On some compilers, the
>> placeholders are function pointers and _1 > _2 can't be overloaded.
>> There's no other technical reason that prevents _1 > _2 (or _1 > 0)
>> from working; it'd fall out of the specification.
>
> Peter, is there still a good reason for this implementation detail?

The reason is still as stated above. :-)

> If people could write:
>
>
>  *_1 < *_2
>
> it would make a killer demo.

*_1 < *_2 is different, as the subexpression *_1 requires return type 
deduction. This is Lambda territory at the moment; Boost.Bind doesn't do 
deduction.