[Orgmode] Re: [BABEL] "unset" :var definitions for subtree

[Dan Davison]

"Eric Schulte" <address@hidden> writes:

> [...]
>>> Maybe we could extend the :var header argument to support the following
>>> syntax...
>>>
>>> #+begin_src emacs-lisp :var A=1 B=3
>>>   ;; code
>>> #+end_src
>>>
>>> or
>>>
>>> ** two vars in a properties block
>>>    :PROPERTIES:
>>>    :var:      test1=7 test2=8
>>>    :END:
>>>
>>> That shouldn't be overly difficult, and should solve our requirements.
>>
>> Yes, that looks good. 
>>
>> In the following Org file
>>
>> ---------------------------------------
>> #+property: :var a=1 b=2
>>
>> * h1
>>   :PROPERTIES:
>>   :var: c=3
>>   :END:
>> ** h11
>>    :PROPERTIES:
>>    :var: d=4 e=5 b=7
>>    :END:
>>
>> #+begin_src sh :var f=6
>> # code here
>> #+end_src
>> ---------------------------------------
>>
>> if we follow programming languages by analogy then the behavior we
>> should aim for is for variables a,b,c,d,e to all be set in the src
>> block, with b having the value 7.
>>
>> I've made a start on a patch to do that -- it involves treating :var
>> differently from other header args. Whereas normal property inheritance
>> searches up the tree until the specified property is encountered, my
>> patch searches up the tree to the root, collecting all the :var
>> assignments encountered.
>>
>
> Maybe we should do this sort of exhaustive search for *all* header
> argument types.  Are there any header arguments aside from :var which
> could possibly want to take multiple values collected at different
> levels of inheritance?  I suppose :results may also take multiple values
> which could reasonably be collected across multiple levels of hierarchy.
>
>>
>> So perhaps we should go for a solution involving both the new ":var a=1
>> b=2" syntax (to allow multiple :var in the same block), and the
>> pluralistic inheritance described above (to allow :var to be collected
>> from all levels in the hierarchy).
>>
>
> That sounds good to me.  Is this code up in a repository somewhere, or
> should be send patches back and forth?

This is in branch ob-inherit at
https://github.com/dandavison/org-devel. I've given you write access to
the repo. The branch isn't ready to go yet, just a first
pass. Currently, with this file

-------------------------------------
#+property: var a=1
#+property: var b=2

* h1
  :PROPERTIES:
  :var: c=3
  :END:
** h11
   :PROPERTIES:
   :var: b=4
   :END:

#+begin_src sh :var d=5
# code here
#+end_src
-------------------------------------

C-c C-v C-v in the src block gives

---------------------------------
c=3
a=1
b=2
d=5
# code here
---------------------------------

(so b has the wrong value, but there will be more issues than just that)

Dan

>
> Best -- Eric
>
>>
>> Dan
>>
>>
>>
>>>
>>> Sound good? -- Eric
>>>
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>
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