Re: [boost] boost::mem_fn suggestion/question

From: Peter Dimov (pdimov_at_[hidden])
Date: 2007-05-15 17:12:46

Piyo wrote:
> Peter Dimov wrote:
>>
>> I'm somewhat reluctant to introduce features into boost::mem_fn since
>> std::tr1::mem_fn and the upcoming std::mem_fn don't/won't have them.
>> If you start using ::argN_type, you won't be able to switch to
>> std::mem_fn once it becomes available. Of course if this is not a
>> concern for the Boost community we can easily add the typedefs and
>> the arity.
>>
>
> Hi Peter,
>
> Several questions:
> - when C++0x gets published and when compilers are fully tr1
> compliant,
> do you see boost::mem_fn (and the rest of the tr1 overlap) go away
> from boost?

Once std::mem_fn is widely available, there'll be no reason to use 
boost::mem_fn, except for old compilers. When the list of Boost-supported 
compilers no longer includes a compiler that doesn't have a std::mem_fn, 
boost/mem_fn.hpp can be reduced to:

#include <functional>
namespace boost { using std::mem_fn; }

> - I was also interested into the rationale why it was omitted also.
> I was looking at the mem_fn tr1 proposal and noticed that argN_types
> were not mentioned. Was it simply because no one so far wanted it?

Lack of demand is one reason. Another is that mem_fn has a first argument 
that cannot be expressed as a typedef. There are probably others.