[yocto] Using anonymous python function to define variables

[Paul Eggleton]

Hi Ulf,

On Sunday 07 December 2014 12:22:06 Ulf Winberg wrote:
> I'm struggling with trying to dynamically set a file name, to be used with
> "require". See code below:
> 
> python () {
>        TA = d.getVar('TARGET_ARCH', True)
>        if TA == "arm":
>                javaPkg = "oracle-jse-ejre-arm-vfp-hflt-client-headless"
>        elif TA == "i586":
>                javaPkg = "oracle-jse-jre-i586"
>        elif TA == "x86_64":
>                javaPkg = "oracle-jse-jre-x86-64"
>        else:
>                raise Exception("Target architecture '%s' is not supported
> by the meta-oracle-java layer" %TA)
>        d.setVar('JAVA_PKG', javaPkg)
> }
> 
> require ${JAVA_PKG}.inc
> 
> The python function executes properly (if I print javaPkg, it shows up
> correctly) but the "JAVA_PKG" variable does not become available for
> "require". From what I can read in section 3.4.4 in this link
> <http://www.yoctoproject.org/docs/1.6/bitbake-user-manual/bitbake-user-manua
> l.html>, it seems to me it should work. Could someone please explain to me
> why it doesn't?

I'm pretty sure this is because anonymous functions don't get executed until 
finalize() is called, which is towards the end of parsing; the "require" 
statement must be handled immediately. Try this instead:

---------------- snip ----------------

def get_java_package(d):
    TA = d.getVar('TARGET_ARCH', True)
    if TA == "arm":
        javaPkg = "oracle-jse-ejre-arm-vfp-hflt-client-headless"
    elif TA == "i586":
        javaPkg = "oracle-jse-jre-i586"
    elif TA == "x86_64":
        javaPkg = "oracle-jse-jre-x86-64"
    else:
        raise bb.parse.SkipPackage("Target architecture '%s' is not supported 
by the meta-oracle-java layer" % TA)
    return javaPkg

JAVA_PKG = "${@get_java_package(d)}"

require ${JAVA_PKG}.inc

---------------- snip ----------------

The question is though, do you really need a separate inc file for each 
architecture? You can use overrides for this sort of thing e.g.:

---------------- snip ----------------

SOMEVAR = "default value"
SOMEVAR_arm = "value if arm"
SOMEVAR_x86-64 = "value if x86-64"

---------------- snip ----------------

Cheers,
Paul

-- 

Paul Eggleton
Intel Open Source Technology Centre