Re: [jamboost] Re: how to kill off property-adjuster

From: Vladimir Prus (ghost_at_[hidden])
Date: 2003-08-29 03:10:54

David Abrahams wrote:
> Christopher Currie <Christopher_at_[hidden]> writes:
> >> I think the problem here is that the user doesn't have a way to say,
> >> "this thing is really just a dependency of some other main target;
> >> don't build it by default".
> >>
> >> dependency lib B : b.cpp ;
> >>
> >> or
> >>
> >> lib B : b.cpp ;
> >> don't-build B ;
> >>
> >> or some such thing.
> >
> > I believe Milestone 6 has a rule, 'explicit', that does what you want.
> >
> > http://boost.sourceforge.net/boost-build2/boost_build_v2.html#explicit_ru
> >le
>
> Great! But the contentious issue will still be: "can we *please* get
> rid of property-adjuster?"

The problem is that "explicit" provides a different solution that 
property-adjuster. Back you your example:

exe A : <library>B c.cpp : <rtti>off ;
lib B : b.cpp ;

If I run "bjam define=FOO", I expect everything to be built with -DFOO. I 
don't expect two versions of "B" to be created. If "B" is explicit and we 
have no property adjuster, only one version is created. But that version is 
not compiled with -DFOO. "explicit", therefore, eliminates build of the 
library that we want to use.

The problem, you know, if that while I find semantic of "bjam define=FOO" 
quite clear from the user POV, I don't know what users say and if they care 
at all. Maybe, this "smart" behaviour is really not needed, but I can readily 
imagine users writing emails saying that define=FOO has no effect and 
Boost.Build is buggy.

- Volodya