Re: propagation of usage-requirements

From: David Abrahams (dave_at_[hidden])
Date: 2004-12-17 08:54:44

Toon Knapen wrote:
> David Abrahams wrote:
> 
>> 
>> Of course I agree with everything you have said. I am only arguing that
>> the author of B should be able to be explicit about which of A's
>> usage-requirements are propogated on to B's clients.
>> 
> 
> Is there a use-case for this? I can't think of a usage-requirement that 
> I do _not_ want to propagate to direct but also indirect dependents. 
> Could you give an explicit example?

Very simple: libB uses libC as an implementation detail, and so needs
libC's headers to be in its #include path. libC's headers are not
#included in any of libB's headers. libA doesn't need libC's headers in
its #include path; it only directly uses libB.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com