Re: Bug: ob-python mangles multiline :var values [9.3.6 (release_9.3.6-397-ga089600)]

[Jack Kamm]

An update on this -- I decided to revert my fix for multiline Python
variables. I left the unit test I added for this, but marked it as
expected to fail.

I'll try to submit a proper fix for this soon. However I've been swamped
at work so I can't promise when (hopefully a couple weeks). In the
meantime, I think it better to leave the original bug in place, rather
than break any existing ob-python use cases.

When I do get to this, I'll submit it as a patch to the list first, to
make sure I don't accidentally cause a new bug.

Best,
Jack

Jack Kamm <jackkamm@gmail.com> writes:

> Hi Matt --
>
>> A heads up... I believe this changes the scope of the :var variables,
>> since they previously were local to the main() function and now they are
>> declared globally. After this change, some of my existing python source
>> blocks (i.e., ones in which I attempt to assign a new value to a
>> variable defined by :var) now generate the following error:
>>
>> Traceback (most recent call last):
>>   File "<stdin>", line 223, in <module>
>>   File "<stdin>", line 214, in main
>> UnboundLocalError: local variable 'members' referenced before assignment
>
> Thanks for noticing this and pointing it out. This was an oversight on
> my end (I don't really use ":var" or non-session blocks).
>
> Unfortunately, the fix for the original bug will have to be a bit more
> complicated to avoid this error. I'll put it on my todo list, but if
> anyone wants to have a crack at it, that would be very welcome.
>
> We should also add a unit test for this regression so it doesn't happen
> again.
>
>> I hesitate to call this a bug, since it would be fine to think of
>> everything within the source block as local and the header :var
>> declarations as global.
>
> I think it's fair to call this a bug. I think it would be inconvenient
> to be unable to assign to these variables. Also, I did not intend to
> break any existing code with this.
>
>> And I suppose it would be worthwhile to ask: Is this change consistent
>> with other org-babel modules? Is there a canonical way that org-babel
>> handles scope?
>
> IMO everything ought to be in the same scope, and the user shouldn't
> have to think about the scope of the main() function that ob-python
> wraps the body in. Especially since non-session blocks are evaluated
> independently of other blocks, we really shouldn't have to think about
> their scope.
>
> I'm not sure if the Org manual provides any guidance here, but from a
> quick check I didn't see anything about it.
>
> Ideally I think everything should just be in global scope; however
> ob-python needs to use a wrapper function for the "return" keyword.