Re: [jamboost] Some thoughts on targets

From: Rene Rivera (grafik666_at_[hidden])
Date: 2003-06-03 11:39:11

[2003-06-03] Ali Azarbayejani wrote:

>Vladimir Prus wrote:
> >
>> For example:
>> 
>> exe hello : hello.cpp @/stlport/stlport ;
>> exe hello : hello.cpp : <library>@/stlport/stlport ;
>> 
>> In both cases, everything must work if @/stlport/stlport produces
>> 1. A target for a searched-library
>> 2. A target which only conveys usage-requirements, but is not intended to
be 
>> consumed.
>> 3. No targets at all
>> 
>> Opinions?
>
>I'm thinking of this both in terms of the existing design and the new 
>Target design I'm working on. In both cases, this sounds like an 
>appropriate application of the "run-actions" functionality.
>
>There is a rule "feature.action" which registers rules to run associated 
>with either a feature or a property. The rule is run in the context of 
>processed properties and it is in the new design the very last stage of 
>property processing (in the current design it is near the end of 
>property processing). Each rule may create new properties to add to the 
>property set.
>
>So, we should always write
>
> exe hello : hello.cpp <stdlib>stlport ;
>
>and should register
>
> feature.action <stdlib>stlport : process-stlport ;
>
>and define
>
> rule process-stlport registered-property : context-properties
> {
> // return appropriate combination of
> // <library>@/stlport/stlport
> // <include>...
> // <define>...
> // etc.
> }
>
>The only problem with this approach is that it won't work (I think). 
>Because in both the existing and new designs, these rules get called 
>after dependencies are generated (so the library won't be processed 
>correctly). Of course, this rule could do that generation as well...

That sounds basically like the modifiers concept, except that modifiers work
both before and after (AFAIK/remember) generation of dependencies. And is
not limited to properties, it can modify the name, properties, sources, and
mutiple option of a target.

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