Re: [boost] [config] request for BOOST_NO_FWD_STD_DECLARATION

Subject: Re: [boost] [config] request for BOOST_NO_FWD_STD_DECLARATION
From: John Maddock (boost.regex_at_[hidden])
Date: 2011-02-16 12:10:25

>>> We've already got such a thing, it's called
>>> 'boost/detail/container_fwd.hpp'. It deals with all the containers
>>> because it was originally written for the hash library, which needs
>>> them all. But IMO If you just want a single container, you might as
>>> well just include the header. They're not that expensive.
>>
>> In which case do we need to do anything - other than make the libraries 
>> that should use that header but don't, use it?
>
> This might pull in a lot more than those libraries need, particularly in 
> the case where we don't use the forward declarations, but pull in all the 
> headers. In the extreme case some places just want pair (although they 
> could just include <utility>)

Well they might... but shouldn't we doing something like:

* If you need several, use container_fwd.hpp.
* If you need one, just include the necessary header (forward declaring pair 
is just plain silly IMO).
* If you need two, then choose which is worst - including two std lib 
headers or container_fwd.hpp.

John.