Re: propagation of usage-requirements

From: David Abrahams (dave_at_[hidden])
Date: 2004-12-16 22:50:29

Toon Knapen wrote:
> Vladimir Prus wrote:
> 
>> 
>> I think it's a conflict between "explicit" and "convenient". No matter what 
>> guidelines are there ("explicit is better than implicit", for example), I 
>> often find that decision is not easy. In this case, Toon did not like too 
>> explicit behaviour. 
> 
> AFAICT it's not about 'implicit' or 'explicit'. Generally I'm also for 
> 'explicit'.
> 
> But suppose library C uses library B which on its turn uses library A. I 
> don't think the developer of library C (and thus which uses library B) 
> should know that library B relies on library A. It's the developer of 
> library B that states in his jamfile that B is dependent on A. C only 
> uses B. Even more: Suppose library C is not changed but all of a sudden 
> library B decides to add some dependency to libZ. This should certainly 
> not induce a change to the build-specification (==Jamfile) of library C, 
> only to the build-specification of library B.

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.

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