Re: [Boost-build] Building Boost with multiple python versions

Subject: Re: [Boost-build] Building Boost with multiple python versions
From: Rene Rivera (grafikrobot_at_[hidden])
Date: 2017-02-15 16:41:02

On Wed, Feb 15, 2017 at 10:32 AM, Stefan Seefeld <stefan_at_[hidden]>
wrote:

> On 15.02.2017 11:25, Rene Rivera wrote:
> >
> >
> > On Wed, Feb 15, 2017 at 10:23 AM, Stefan Seefeld via Boost-build
> > <boost-build_at_[hidden] <mailto:boost-build_at_[hidden]>>
> wrote:
> >
> >     Hi Aaron,
> >
> >     On 15.02.2017 11:18, Aaron Boman via Boost-build wrote:
> >     > The "using" rule is a convenience rule:
> >     >
> >     > using MODULE_NAME : field1 : field 2 : ... : field9 ;
> >     >
> >     > The above essentially does this:
> >     >
> >     > import MODULE_NAME ;
> >     > MODULE_NAME.init field1 : field2 : ... : field9 ;
> >     >
> >     > So, if you look at the gcc.jam module, you'll notice that its
> init()
> >     > rule's signature is this:
> >     >
> >     > rule init ( version ? : command * : options * )
> >     >
> >     > Thus, the using rule would be used like this:
> >     >
> >     > using gcc : $(valid-gcc-module-version-string) :
> >     > $(optional-command-to-gcc-exe) : $(options) ;
> >     >
> >     > Where $(options) can be something like <root>root/directory or
> >     > <flavor>mingw.
> >     >
> >     > You can find the using() rule's definition in the toolset module.
> >
> >     thanks, but I don't think that answers any of the questions.
> >     Specifically, my last question was about the 'version' argument to
> the
> >     gcc.init() function. Is it used to identify a compiler by version ?
> Or
> >     can it be an arbitrary string / discriminator I use to configure
> >     compilers with different flags (e.g. `--std=c++11` vs.
> >     `--std=c++03`) ?
> >
> >
> > For gcc it can be an arbitrary string.
>
> How then does
>
> using gcc : 6.3 ;
> using gcc : 5.3 ;
>
> work in practice ? How does b2 look up the appropriate compilers, if it
> doesn't somehow match the version strings in the above snippet with the
> output of `gcc --version` ?
>
> > If I understand the python init code correctly, which is a challenge
> > even for me, for python it must be the version of the interpreter (ie
> > it checks that it matches).
>
> OK. So for Python the proposed trick of using a "labeled version" to
> name a specific Python instance unambiguously (e.g. in the presence of a
> 32-bit Python and a 64-bit Python of the same version) wouldn't work, yes ?
>

Probably not.. As in I'm still trying to decipher the python.jam code.

-- 
-- Rene Rivera
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