Re: [Boost-build] Alias requirements?

Subject: Re: [Boost-build] Alias requirements?
From: Gevorg Voskanyan (v_gevorg_at_[hidden])
Date: 2010-11-29 04:17:38

Vladimir Prus wrote:
> On Monday, November 29, 2010 10:53:17 Gevorg Voskanyan wrote:
> > I feel I  must be missing something obvious, but are alias requirements
> > supposed  to work? Consider this simple case:
> > 
> > alias src : a.cpp b.cpp :  <define>FOO ;
> 
> This says:
> 
>     Whenever  somebody asks for 'src', take metargets a.cpp and b.cpp, and 
>         generate them with <define>FOO, then return result. 
> 
> However, given that a.cpp and b.cpp are source files, generating them  merely
> creates targets, and <define>FOO is not used in any way. 

I *think* I see what you mean, however the following variation confuses things 
for me again:

obj a : a.cpp ;
obj b : b.cpp ;
alias src : a b : <define>FOO ;

As far as I understand, this time 'a' and 'b' are proper metatargets, and 
generating them with <define>FOO should work. But I just tried it and 
<define>FOO wasn't present this time either.

> > exe e : main.cpp src ;
> > 
> > Here both a.cpp and b.cpp  get built without FOO being defined. Changing
> > 'alias' with 'lib' fixes  the things and causes FOO to be properly defined
> > for a.cpp and  b.cpp.
> 
> Yes, because in that case, <define>FOO applies to the 'lib'  target, and 'lib'
> target can make some use of it.
> 
> Does this clarifies  things?

> -- 
> Vladimir  Prus
> http://vladimir_prus.blogspot.com
> Boost.Build:  http://boost.org/boost-build2