Re: python function used in variable expansion called multiple times per recipe

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Thu, 2012-04-19 at 21:24 +0000, Daniel Lazzari wrote:
> >> I think immediate expansion is what I’ll need to use, thanks for the tip.
> >> That at least brings the invocation down to once per run. Unfortunately, the
> >> variable doesn’t seem to get filled in when I change to immediate
> >expansion.
> >>
> >> def testFunc(bb, d):
> >>                 print( bb.data.getVar("PN", d, True) )
> >>                 return "e1"
> >>
> >> EXTERNPV := "${@testFunc(bb, d)}"
> >>
> >> Now only prints the package name once, but using –e, I don’t see the
> >> variable EXTERNPV at all.
> >
> >Don't know what to tell you. It does work, so it's something wrong on
> >your end. Either it's returning an empty string, which will result in
> >-e only showing the commented out definition, or it's raising an
> >exception, or something else in your setup. Aside: you don't need to
> >pass 'bb' in. That namespace is always accessible, even from def'd
> >python functions.
> >--
> >Christopher Larson
> 
> Just thought I'd provide an update real quick on this. I discovered,
> to my dismay, that even doing an immediate expansion still ran the
> code before every task for that recipe. I switched to using an event
> handler, but the RecipeParsed event occurs before every task for that
> recipe. Eventually I discovered that the variable BB_WORKERCONTEXT is
> set for RecipeParsed events when they are occurring before a task, but
> not for the initial parse. Also, I discovered that setting a variable
> in the event handler would not necessarily keep it set through
> building the recipe. Thus I devised the below code to run the time
> intensive code during initial parse and cache the value in a file so
> it can be picked up again in later events. I'm leaving this here in
> case it helps someone else.

Just as a note, we have the persist_data code in bitbake which was
written for this kind of reason in relation to SRCREV and AUTOINC which
uses a sqlite backend as the storage. There isn't anything wrong with
what you're doing, I just thought I'd mention it.

Cheers,

Richard