AMDG

On 02/09/2018 06:25 AM, Rene Rivera via Boost-build wrote:
> On Fri, Feb 9, 2018 at 7:07 AM, Fabien Chêne via Boost-build <
> boost-build@lists.boost.org> wrote:
>
>>
>> I was wondering if it were possible to extend the bjam grammar so that:
>>
>> rule lib ( name : sources * : requirements * )
>>
>> can be called either (possibly using named arguments coming from the
>> rule definition):
>> lib foo : a.C b.C : requirements <define>XXX ;
>> lib foo : sources a.C b.C : requirements <define>XXX ;
>> lib foo : requirements <define>XXX : sources a.C b.C ;
>> lib sources a.C b.C : name foo : requirements <define>XXX ;
>>
>> What do you think ?
>>
>

  I already implemented this in develop.  It is implemented
as a library extension rather than a language extension,
so rules must explicitly make use of it:

param.handle-named-params sources requirements
  default-build usage-requirements ;

I applied it to all main-target rules.

> IIRC we discussed this some long time ago.. You example usage is not "easy"
> to accomplish in a backward compatible way.

  It's true that it isn't perfectly backwards compatible,
but I didn't find any conflicts in Boost.  Also, applying
it on a per-rule basis is much safer than baking it into
the language.

> The best alternative that I
> remember was having the argument names be a special format. For example:
>
> lib foo : a.C b.C :requirements <define>XXX ;
> lib foo :sources a.C b.C :requirements <define>XXX ;
> lib foo :requirements <define>XXX :sources a.C b.C ;
> lib :sources a.C b.C :name foo :requirements <define>XXX ;
>
> That is having named arguments be ":<arg-name> arg .." (colon prefixed).
> Which would allow to distinguish them and the list value from all the other
> arguments. How does that sound to you?
>

That syntax conflicts with changing the lexer.