Re: Alternatives and underfined feature values

From: Reece Dunn (msclrhd_at_[hidden])
Date: 2005-02-11 09:21:44

Vladimir Prus wrote:
> On Friday 04 February 2005 19:13, Pedro Ferreira wrote:
> 
>>>>>3. Allow the user to say that <toolset>msvc
>>>>>is valid, without initializing the toolset.
>>>>
>>>>I like #3. It seems to be the cleanest of your proposals. In fact I
>>>>think that all toolsets shiped with BB2 should be valid by default.
>>>
>>>This would be great. But I dont think that *automagically* scanning all
>>>toolsets would be a great idea.
>>>
>>>>The same goes for the <os> feature that has the same problem.
>>>
>>>I'm +1 for an explicit list of "configured" values for <toolset> and
>>><os>. So bjam can check for syntax errors.
>>
>>In principle, I agree but how does one implement it? Hardcoding a list
>>of supported OSs and toolsets?
>>Looks a bit awkward... but I think it's better than the other approches.
> 
> So, everybody prefers #3. Now it's time to express my opinion.
> 
> I think we absolutely need #2 to fix 
> http://zigzag.cs.msu.su:7814/scarab/issues/id/BB78
> 
> This means that the *recommended* way to declare alternatives becomes:
> 
> lib a : a_msvc.cpp : when <toolset>msvc-6.0 ;
> lib a : a_vc7.cpp : when <toolset>msvc-7.1 ;
> 
> I think it's acceptable, given that alternatives are not very common.

It also makes it easier to distinguish between the build configuration 
and alternative selection. Note that this needs to work for:

lib a : a_generic.cpp ;
lib a : a_msvc.cpp : when <toolset>msvc ;

Although I prefer something like "using" as opposed to "when":

lib a : a_msvc.cpp : using <toolset>msvc ;

Regards,
Reece