Re: [boost] [config] request for BOOST_NO_FWD_STD_DECLARATION

Subject: Re: [boost] [config] request for BOOST_NO_FWD_STD_DECLARATION
From: Christopher Jefferson (chris_at_[hidden])
Date: 2011-02-16 11:59:30

On 16 Feb 2011, at 16:56, John Maddock wrote:

>>> Can't this be taken one step further, and introduce something
>>> like boost/details/stdfwd.hpp, or maybe boost/stdfwd.hpp? In
>>> the case where forwarding is not possible, stdfwd.hpp would
>>> have to include all std::containers
>> 
>> In the fallback case, you'd force inclusion of <map>, <multimap>, <set>, etc. for some context that, otherwise, would only have included, say, <vector>. That's not a good tradeoff. Instead of stdfwd.hpp, it'll have to be map_fwd.hpp, multimap_fwd.hpp, and so on.
> 
>> 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>)

Chris