Re: [gentoo-dev] Re: The meaning of || ( a:= b:= ) dependencies

[Michał Górny]

Dnia 2014-08-04, o godz. 08:06:42
Ulrich Mueller <ulm@g.o> napisał(a):

> >>>>> On Mon, 4 Aug 2014, Michał Górny wrote:
> > In particular, I was thinking we could reuse this syntax:
>
> >   || ( A:= B:= )
>
> > to express any-of dependencies that do not support runtime switching
> > of providers -- since that is pretty much what := does to slots.
> > This would save us from creating a new syntax like '||= ()' [1].
>
> Please don't, because it makes things pretty much unreadable. If you
> want an operator like || ( ) but without runtime switching, then
> define one (e.g., <<= or ||= as suggested in [1]), but don't try
> to inherit properties from its children.

Reasonable. However, as I see it, we'll end up having up to four
different operators:

- || that is deprecated yet everyone will still use it (like they don't
  use :* right now),

- ||* that will be used scarcely,

- <<= that would be the preferred variant for compile-time switches yet
  many people will not use it because it has different characters than
  '||' [we could try maybe '||<' so that people will still see it as
  replacement for '||'],

- ||= that most people would use forgetting about '<<=' [or '||<'].

So, banning '|| ( A:= B:= )' in a future EAPI sounds reasonable.
However, there's still the matter of setting current Portage behavior
because I don't we should keep the non-predictable magic.

What should be the current behavior then? Should we assume that all
'||' are not well-defined and need to be compile-switchable? Or try to
invent heuristic like I suggested?

-- 
Best regards,
Michał Górny