Re: [ANN] BREAKING CHANGE -- removing #+BABEL file-wide property lines

[Rainer M Krug <r.m.krug@gmail.com>]

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On Sat, Oct 22, 2011 at 9:07 PM, Christian Moe <mail@christianmoe.com>wrote:

> Hi,
>
>
> Eric Schulte wrote:
>
>>
>>
>  I can think of three options for how to handle this situation.
>>
>> 1. If it turns out to be possible/desirable my preferred solution
>> here would be to add general property support for appending values
>> to properties when properties are over specified
>>
> (...)
>
>
>> 2. Adding a "#+PROPERTY:" line authoring helper similar to the
>> table formula helper making it more natural to edit such long
>> property lines.
>>
>> 3. It may be possible to add syntax for extending #+PROPERTY:
>> specifications across multiple lines, something like
>>
>> #+PROPERTY: var MAINVERSION=0,
>>
> > #+PROPERTY+: SVNVERSION=(vc-working-**revision (buffer-file-name)),
> (...)
>
> These are all interesting ideas, as was Darlan's alternative suggestion to
> Eric's suggestion (1), namely to use a special inherit argument.
>
> I'd like to toss out a different idea, which I think is brilliant, but
> which may go down in flames once we've had a time to think it through. (And
> sorry if it's been proposed before; I came to Org just as Org-Babel was
> being stabilized.)
>
> In short, let Babel assign to any declared variables of a src block the
> values of any properties at point with the same name. In other words:
>
> - The :var header argument / :var: property could declare variables without
> assigning values, that is, you could have
> `:var foo=1, bar, baz=3' to tell Babel that `bar' is a variable too.
>
> - When a variable is declared, but no value assigned, Babel would look for
> a property (e.g. `:bar: 2') at point with the same name as the variable.
>
> - If property inheritance is turned on, this means a variable can be
> specified at any level of the outline.
>
> - If no further changes were made (such as the property accumulation Eric
> suggested), it would still be possible to /declare/ variables only at /one/
> level of the outline besides in the code block and calls, since declarations
> all belong to the same `:var:' property. However, this approach would mean
> that declarations could be kept short and there would be a great deal of
> modularity in what values would be assigned.



This all sounds very interesting, but I have problems understanding the
advantages - possibly because I only had one coffee this morning. In
addition see further down:

SNIP


> On 10/22/11 5:52 PM, Eric Schulte wrote:
>
>>
>>> #+BABEL: :var MAINVERSION=0
>>> #+BABEL: :var SVNVERSION=(vc-working-**revision (buffer-file-name))
>>> #+BABEL: :var SVNSTATE=( symbol-name (vc-state (or (buffer-file-name)
>>> org-current-export-file)))
>>> #+BABEL: :var SVNSTATENUM=(if (eq (vc-state (or (buffer-file-name)
>>> org-current-export-file)) 'up-to-date) 0 13)
>>> #+BABEL: :var DISP_PACKAGE="seedDisp_0.4-13.**tar.gz"
>>>
>>>
> Have a buffer-level property for all the long lines (sorry if my email
> client wraps these lines):
>
> #+PROPERTY: SVNVERSION (vc-working-revision (buffer-file-name))
> #+PROPERTY: SVNSTATE ( symbol-name (vc-state (or (buffer-file-name)
> org-current-export-file)))
> #+PROPERTY: SVNSTATENUM (if (eq (vc-state (or (buffer-file-name)
> org-current-export-file)) 'up-to-date) 0 13)
> #+PROPERTY: DISP_PACKAGE "seedDisp_0.4-13.tar.gz"
>
>
I think this syntax opens the door for dangerous typos - If you type e.g:

#+PROPERTY: vat x=10

what would this be? it should have been

#+PROPERTY: var x=10

but now? One could allow this syntax in the case that the variable has been
defined before, by using the var syntax:

so

#+PROPERTY: var MAINVERSION=0, SVNVERSION, SVNSTATE, SVNSTATENUM,
DISP_PACKAGE
#+PROPERTY: SVNVERSION (vc-working-revision (buffer-file-name))
#+PROPERTY: SVNSTATE ( symbol-name (vc-state (or (buffer-file-name)
org-current-export-file)))
#+PROPERTY: SVNSTATENUM (if (eq (vc-state (or (buffer-file-name)
org-current-export-file)) 'up-to-date) 0 13)
#+PROPERTY: DISP_PACKAGE "seedDisp_0.4-13.tar.gz"

should be OK, as SVNVERSION is already defined, but

#+PROPERTY: SVNVERSION (vc-working-revision (buffer-file-name))
#+PROPERTY: SVNSTATE ( symbol-name (vc-state (or (buffer-file-name)
org-current-export-file)))
#+PROPERTY: SVNSTATENUM (if (eq (vc-state (or (buffer-file-name)
org-current-export-file)) 'up-to-date) 0 13)
#+PROPERTY: DISP_PACKAGE "seedDisp_0.4-13.tar.gz"
#+PROPERTY: var MAINVERSION=0, SVNVERSION, SVNSTATE, SVNSTATENUM,
DISP_PACKAGE

not, as the variables are only defined later.


But this would not make

#+PROPERTY+:

redundant, but rather enhance it.

Cheers,

Rainer

Cheers,

Rainer



SNIP


> Yours,
> Christian
>



-- 
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology,
UCT), Dipl. Phys. (Germany)

Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa

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