Re: [Boost-build] How to write such a feature?

Subject: Re: [Boost-build] How to write such a feature?
From: Sherwood Hu (sherwood_at_[hidden])
Date: 2009-09-22 10:27:54

Steven,

Thanks. I followed the instruction and they worked.

feature enable-unit-test : on off : composite propagated ;
feature.set-default enable-unit-test : off ;
feature.compose <enable-unit-test>on : <define>_UNIT_TEST ;

feature enable-debug-module : on off : composite propagated ;
feature.set-default enable-debug-module : off ;
feature.compose <enable-debug-module>on : <define>BK_DEBUG_MODULE ;

Now I have another question. The attribute "propagated" is quite strong
and applies on the whole dependency tree. Is there an attribute that
only applies to one target but stronger than what the "free" attribute
can provide?

Assume that my unit test exe is linked to libA, which has dependency
libB. I want the new feature <enable-debug-module> only applies to libA
not libB. That is, the test exe is linked to libA built with
<enable-debug-module>on and libB built with <enable-debug-module>off.

Is this possible?

-----Original Message-----
From: boost-build-bounces_at_[hidden]
[mailto:boost-build-bounces_at_[hidden]] On Behalf Of Steven
Watanabe
Sent: Tuesday, September 22, 2009 12:17 AM
To: Boost.Build developer's and user's list
Subject: Re: [Boost-build] How to write such a feature?

AMDG

Sherwood Hu wrote:
> The <define> property in Boost.Build does not propagate. This causes
> problems in my project, as the unit tests require a macro UNIT_TEST to
> be defined and the main library is built with this macro defined.
> Because <define> does not propagate, I have to specify
<define>UNIT_TEST
> at the command line. If the library is built first without this macro,
> the unit tests will not be built successfully. 
>
> I am considering to add a <unit-test> feature and make
<define>UNIT_TEST
> propagate. 
>
> Import feature : feature ;
>
> Feature unit-test : on off : propagated ;
>
> But how to add <define>UNIT_TEST when <unit-test>on? 
>   

Use a composite feature.  They are documented at the bottom of
http://www.boost.org/boost-build2/doc/html/bbv2/extending/features.html

In Christ,
Steven Watanabe

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