Re: [Boost-build] Specifying define on command line

From: Phillip Seaver (phil_at_[hidden])
Date: 2007-08-06 08:29:17

David Abrahams wrote:
> on Sun Aug 05 2007, Vladimir Prus <ghost-AT-cs.msu.su> wrote:
>
>   
>> I see two solutions:
>>
>> 	1. Make 'free' features like 'define' and 'cflags' propagated. This
>> 	will have undesirable effect that <define> set on some target
>> 	will propagate to all dependencies.
>> 	2. Make free features specified on the command like apply to
>> 	all targets in the project located in ".", and any child project.
>> 	The only concern I have about this approach is that it will
>> 	still be impossible to specify define that will apply to all
>> 	compilations. That is, if I have two projects A and B,
>> 	in different directories with separate Jamroots, where A uses
>> 	libraries from B, then:
>>
>> 		bjam define=FOO
>>
>> 	in A won't affect B.
>>
>> Anybody can comment on those alternative or propose better ones?
>>     
>
> 3. Free features on the command line apply globally.
>
> 3 is the simplest way to address the problem, and probably matches
> most people's expectations.  I think 1 is the wrong way.  The command
> line options are an expedient and blunt instrument for developers who
> think they know what they're doing; I think they should be treated
> altogether differently from build properties specified in Jamfiles,
> which can be carefully tuned.

I don't have a strong opinion on 2 vs. 3, but I agree that 1 is not a
good idea.  There are some libraries that need defines set for building
which are unnecessary (and maybe even incorrect) for using the library.

Phillip