Re: [jamboost] More on features

From: Vladimir Prus (ghost_at_[hidden])
Date: 2002-08-08 02:20:43

David Abrahams wrote:

> > But while we're on this topic, I have anyther suggestion. We were
>
> planning to
>
> > support things like stlport using special generators, which would just
>
> modify
>
> > build properties. I've done some initial work on generators, and they
>
> appear
>
> > to be not so simple a thing. For that reason, I'd prefer not to
>
> complicate
>
> > them more and support stlport et al in a different way.
> >
> > Let's make "active" properties and features. If build properties for a
>
> main
>
> > target contain an active property, like
> >
> > <stdlib>stlport
> >
> > then a previously registered rule will be called which will adjust
>
> properties.
>
> Hmm, "exectuted" properties anyone?

Yea, except with a somewhat different semantics and the fact that you can 
have both executed features (i.e. a rule handles every value of feature) and
executed properties (i.e. rule handles a particular feature, value pair).

> Didn't we just decide we didn't need those?

We haven't yet, IIRC.

> > Likewise, if there's feature
> >
> > python-arity
> >
> > with any value, another rule would translate it into appropriate defines.
> > Opinions?
>
> I worry that this approach won't afford us enough control... but suppose
> I'm wrong? What would we be giving up by taking this approach? Anything?

I don't think we'll give up anything. After all, properties added by executed 
features can affect generators selection, if this is desperately needed in 
some (very few, I think) cases.

> What was the motivation for shoving all of this functionality into
> generators in the first place?

You've proposed it as a way to handle stlport. I don't remember any other 
motivation.

- Volodya