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[Orgmode] Re: [BABEL] "unset" :var definitions for subtree
From: |
Dan Davison |
Subject: |
[Orgmode] Re: [BABEL] "unset" :var definitions for subtree |
Date: |
Sun, 13 Feb 2011 01:38:01 +0000 |
User-agent: |
Gnus/5.110011 (No Gnus v0.11) Emacs/24.0.50 (darwin) |
"Eric Schulte" <address@hidden> writes:
> [...]
>>
>> I agree, the things I was talking about don't end up being simpler in
>> terms of usage for this case. My thinking was that variable unsetting
>> might be something that would be required fairly rarely, and so it might
>> be worth appropriate to support it as part of a more general/powerful
>> mechanism tied into Org properties, or even that hook.
>>
>
> It does sound like if there were a way to disable inheritance for
> certain properties for certain sub-trees of a document, then that would
> be ideal -- although I can't imagine how such functionality would be
> implemented. Can we think of an Org-wide syntax for disinheriting
> specific properties?
I'm not sure whether or how this fits it, but it's worth noting that Org
currently documents the following
,----
| org-entry-get-with-inheritance is a Lisp function in `org.el'.
|
| (org-entry-get-with-inheritance PROPERTY &optional LITERAL-NIL)
|
| Get entry property, and search higher levels if not present.
| The search will stop at the first ancestor which has the property defined.
| If the value found is "nil", return nil to show that the property
| should be considered as undefined (this is the meaning of nil here).
| However, if LITERAL-NIL is set, return the string value "nil" instead.
`----
so that seems to suggest ":var nil" as a way of knocking out all :var
assignments, but doesn't immediately suggest how to knock out on a
per-variable basis. :var a=nil ? (Which otherwise would look for a src
block named "nil")
>> Before we proceed with the variable unsetting, could someone provide a
>> motivating example, just to convince ourselves that the extra features
>> are justified? (The conclusion of another message was that the torque
>> script example was more a motivating example for shebang/preamble
>> processing than for variable unsetting.)
>>
>
> Certainly.
>
> 1. taking Rainer's first example, lets say that you want a variable
> specified for all but one code block in a file (maybe that one code
> block is the source of the value of the variable). In this case it
> would be much simpler to specify the variable file-wide, and then
> unset the variable for that one code block.
Agreed. It's not clean, but currently in this situation one could just
set the offending variable to some other value.
> 2. say you want the same session for /nearly/ every code block in a
> file.
> 3. same for :dir, :file, or :shebang...
I'd just note that some of these already have natural values that can be
used to "unset"
:session none
:dir .
:shebang ""
:file <not sure about this one, but maybe "none" should be used...>
Dan
>
>
> So, in summary, I am all for a general org-mode wide solution for
> disinheriting specific properties, however, if we are unable to find
> such a solution then I would lean towards implementing this for Babel
> specifically.
>
> Best -- Eric
>
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- [Orgmode] Re: [BABEL] "unset" :var definitions for subtree, (continued)
- [Orgmode] Re: [BABEL] "unset" :var definitions for subtree, Dan Davison, 2011/02/11
- [Orgmode] Re: [BABEL] "unset" :var definitions for subtree, Rainer M Krug, 2011/02/11
- Re: [Orgmode] Re: [BABEL] "unset" :var definitions for subtree, Eric Schulte, 2011/02/12
- [Orgmode] Re: [BABEL] "unset" :var definitions for subtree, Dan Davison, 2011/02/12
- [Orgmode] Re: [BABEL] "unset" :var definitions for subtree, Eric Schulte, 2011/02/13
- [Orgmode] Re: [BABEL] "unset" :var definitions for subtree, Dan Davison, 2011/02/13
- [Orgmode] Re: [BABEL] "unset" :var definitions for subtree, Eric Schulte, 2011/02/14
- [Orgmode] Re: [BABEL] "unset" :var definitions for subtree, Eric Schulte, 2011/02/11
- [Orgmode] Re: [BABEL] "unset" :var definitions for subtree, Dan Davison, 2011/02/11
- [Orgmode] Re: [BABEL] "unset" :var definitions for subtree, Eric Schulte, 2011/02/12
- [Orgmode] Re: [BABEL] "unset" :var definitions for subtree,
Dan Davison <=
- [Orgmode] Re: [BABEL] "unset" :var definitions for subtree, Eric Schulte, 2011/02/13