Re: [gentoo-dev] multiple inclusion protection with eclasses

[Alec Warner]

On Thu, Dec 8, 2011 at 2:24 PM, Mike Frysinger <vapier@g.o> wrote:
> ferringb did some tests and found that doing multiple inclusion protection in
> eclasses gets us some nice speed ups.  it isn't nearly as nice as if we had a
> way of skipping the `source` altogether, but that that would require PMS/tree
> changes.  the change i'm proposing can be implemented $now and should work
> with all versions.  PMS extensions can thus be discussed in parallel.
>
> simply put, it's the same thing as doing standard #ifdef logic in headers to
> protect against multiple inclusion errors.  on to the example:
>
> --- autotools.eclass
> +++ autotools.eclass
> @@ -10,6 +10,9 @@
>  # This eclass is for safely handling autotooled software packages that need
>  # regenerate their build scripts.  All functions will abort in case of
>
> +if [[ ${___ECLASS_ONCE_AUTOTOOLS} != "recur -_+^+_- spank" ]] ; then
> +___ECLASS_ONCE_AUTOTOOLS="recur -_+^+_- spank"
> +

Not to rain on your parade; but is that the value you are sticking with?

-A

>  inherit eutils libtool
>
>  # @ECLASS-VARIABLE: WANT_AUTOCONF
> @@ -399,3 +402,5 @@
>
>        echo $include_opts
>  }
> +
> +fi
>
> this assumes that the eclass in question isn't doing something weird.  for
> example, if you had an ebuild today that did:
>        inherit eutils
>        epatch() { die erp; }
>        inherit eutils
>
> that local epatch() would get reset by the eutils inherit.  but i can't see
> any ebuild having a valid reason for doing things like this, so screw 'em.
>
> i plan on implementing this in the eclasses i generally look over.  i don't
> plan on doing it for all eclasses since i'm not familiar with them.
> -mike