[yocto] Undefining a variable in a recipe?

[Alex J Lennon]

On 02/05/2014 14:25, Otavio Salvador wrote:
> On Fri, May 2, 2014 at 10:23 AM, Otavio Salvador
> <otavio at ossystems.com.br> wrote:
>> On Fri, May 2, 2014 at 10:11 AM, Alex J Lennon
>> <ajlennon at dynamicdevices.co.uk> wrote:
>>> Or indeed, would be not be reasonable to modify the uboot-config.bbclass
>>> such that
>>> it tested for and discarded empty strings in UBOOT_MACHINE / UBOOT_CONFIG
>>> which would seem to be a more complete test and would eliminate the
>>> problem ?
>> Like: http://privatepaste.com/8046479967
> Fixed: http://privatepaste.com/3ffec754d4
>

Otavio, thanks for that. Python is not my métier and I had assumed that
the check on  'if ubootmachine' and so forth would check for definition
rather than be a check on a  zero length string.

However given Paul's pointer on Python I've revisited this,

"if len(x) > 0", "if len(x)",  and "if x" are all equivalent tests for empty strings in Python"

I had tried setting UBOOT_CONFIG = "" and UBOOT_MACHINE = "" as that's
what I saw used in the getVar(). This which didn't work for me, and I
wrongly assuming this was because  of the test.

If instead I set the appended machine type, e.g.
UBOOT_MACHINE_im6qsabresd = "", then that works (!) I guess it's being
copied across somewhere.

So thanks again for the advice. I think we've cracked it :)

Cheers,

Alex