[OE-core] can i use bitbake to run an arbitrary python routine in a class file?

[Robert P. J. Day]

On Mon, 2 Jul 2012, Chris Larson wrote:

> On Mon, Jul 2, 2012 at 6:40 AM, Robert P. J. Day <rpjday at crashcourse.ca> wrote:
> >   i'm not even remotely a python expert (working on that, though) so
> > there may be a trivial and documented answer to this -- can i use
> > bitbake to run an arbitrary python routine to see what the output
> > would be?
> >
> >   for example, here's qemu.bbclass:
> >
> > def qemu_target_binary(data):
> >         import bb
> >
> >         target_arch = data.getVar("TARGET_ARCH", True)
> >         if target_arch in ("i486", "i586", "i686"):
> >                 target_arch = "i386"
> >         elif target_arch == "powerpc":
> >                 target_arch = "ppc"
> >
> >         return "qemu-" + target_arch
> >
> > what if i wanted to see what that would return given a current build?
> > can i do that?  does that question even make sense?

... snip ...

> Alternatively, just do:
>
> FOO = "${@qemu_target_binary(d)}"
>
> And then: bitbake -e | grep \^FOO=

  i tried this with a "qemux86" MACHINE selection and got:

# expansion of FOO threw ExpansionError: Failure expanding variable
FOO, expression was ${@qemu_target_binary(d)} which triggered
exception NameError: name 'qemu_target_binary' is not defined

that seemed a bit weird since i was just assuming a qemu-based build
would automatically inherit that class file.  so i added:

INHERIT += "qemu"

to my local.conf and that fixed it.  i was a bit surprised that that
class file wasn't part of a qemu build.  the only class file that
inherits it:

meta/classes/libc-package.bbclass:inherit qemu

  i'm just surprised i picked what looked like a good test case, and
it turned out to not work the way i thought.

rday

-- 

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
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