Re: [Boost-build] Toolset requirements

From: Rene Rivera (grafikrobot_at_[hidden])
Date: 2006-11-15 19:03:25

Vladimir Prus wrote:
> Attached is a patch to implement 'toolset requirements' -- a mechanism for 
> toolset to say "on msvc, with dynamic runtime, use multi-threading". The 
> approach is damn simple -- there's global list of requirements that toolset 
> modules append to. The list is appended to requirements of all main targets,
> as if that list was specified in their requirements.
> 
> With this patch, building with msvc starts using threading=multi.
> 
> If nobody has any objections to this patch, I'll commit it.

As I mentioned on IM, I tried using this to replace the GCC toolset 
logic for static vs. dynamic runtime vs. link generator logic. But it's 
not currently possible AFAICT. I tried adding:

rule check-runtime-link-static ( properties * ) ...

toolset.add-requirements
     <conditional>@gcc.check-runtime-link-static
     ;

That fails because it seems that conditional rules only work if they are 
defined in the Jamfile context for the main targets. But that was after 
trying a more specific:

toolset.add-requirements
 
<toolset>gcc,<target-os>unix,<runtime-link>static:<conditional>@gcc.check-runtime-link-static
 
<toolset>gcc,<target-os>linux,<runtime-link>static:<conditional>@gcc.check-runtime-link-static
     ;

As conditional requirements are not themselves conditional. Not a big 
problem onto itself, it's just that it make the rule itself more compact 
if the above where possible.

Now if you ask why use a conditional rule: It allows for spitting out an 
informative message as to why it's going to add the "<build>no".

I'll see how much farther I can get without using a rule.

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