Re: [jamboost] symmetric/optional features

From: Vladimir Prus (ghost_at_[hidden])
Date: 2002-07-03 11:37:55

David Abrahams wrote:
> From: "Vladimir Prus" <ghost_at_[hidden]>
>
> > David, I've noticed that neither build-request.expand or property.as-path
> > ever check for symmetric or optional properties. So, when those
>
> properties
>
> > make any difference?
>
> Symmetry should affect the definition of new variants (for which we have no
> rule yet).

Then I don't yet understand the definition of symmetric rules. Your earlier 
wrote:

In the current system, <runtime-link> is a symmetric feature. A value is
always chosen for every build, but its default value (dynamic) is not
automatically incorporated into build variants. The result is that the
corresponding subvariant directory always shows up in the subvariant
path, so that subvariant paths always include runtime-link-dynamic or
runtime-link-static.

I now realize that you probably mean that defalt value of every feature which 
is not symmentic should be included in every declared variant? Oh, then I 
understand everything!!!

> Optional features should be accounted for after build-request.expand, I
> think. Once the build-request is expanded, we then look at all non-optional
> features and stick in default values if they're not represented in the
> build.

Yes, you are right. Can you implement it? I guess it should be some new rule 
like "apply-defaults" which should be called after calling 
"build-request.expand" in build-system.jam.

- Volodya