Re: [jamboost] Re: Free feature problem

From: Vladimir Prus (ghost_at_[hidden])
Date: 2004-07-02 10:40:13

David Abrahams wrote:

> >> Seems as though it ought to be unneccessary, doesn't it?
> >
> > Why? The problem is: you want to use <toolset>msvc in requirements.
>
> But only as a condition, right? If it were an actual requirement,
> also asking people to have "using msvc" would be no problem.

Non necessary in condition. If you want to do conditional compilation you have 
two approaches:

lib a : : <toolset>msvc:<source>msvc.cpp <toolset>gcc:<source>gcc.cpp ;

and

lib a : msvc.cpp : <toolset>msvc ;
lib a : gcc.cpp : <toolset>gcc ;

the role of <toolset> property in the second case is similiar to the role in 
the first case. And in the second case, user might well don't have msvs 
installed.

> > You don't want to "using msvc " because that would warn that msvc is
> > not installed. So you need a way to say the <toolset>msvc is OK.
>
> Why shouldn't the person who defines the <toolset> feature do that
> once instead of requiring everyone who wants to use it in a condition
> to do a use-property?

For example, I might have Jamfile which includes uses <toolset>nm in one 
place. Nobody is even has that toolset, so nobody can say "using nm ; ". If I 
want my Jamfiles to be compilable everywhere, I need a mechanism to say, 
"<toolset>nm" is ok.

- Volodya

If he's only going to work on one toolset, 'use-property' is not needed. If 
Jamfile has to be usable by other people,