Re: About the use of PROPERTY "meta lines"...

[Torsten Wagner <torsten.wagner@gmail.com>]

Hmm...
but this point is really interesting at least worse to write down in the 
manual.
 From my understanding a
#+PROPERTY: var bar=2
sets bar globally to 2
somewhere and many lines and headers later
#+PROPERTY: var bar=5
would change this value to 5 for either the rest of the file or until a 
new assignment is given...
in that way a property line would be an tree-independent global variable

in contrast, a property-block is only valid of the given tree (and 
subtrees?).

This brings up the question if there is a need for

#+PROPERTY: const bar=2

which would behave exactly the same like var but issue an error message 
if someone tries to set it again somewhere in the file.

Torsten



On 01/06/2012 04:28 PM, Eric Schulte wrote:
> "Sebastien Vauban"<wxhgmqzgwmuf@spammotel.com>  writes:
>
>> Hi Eric and all,
>>
>> Eric Schulte wrote:
>>> "Sebastien Vauban"<wxhgmqzgwmuf@spammotel.com>  writes:
>>>
>>>> #+TITLE:     Properties
>>>> #+AUTHOR:    Seb Vauban
>>>> #+PROPERTY: var  foo=1
>>>> #+PROPERTY: var+ bar=2
>>>>
>>>> * Abstract
>>>>
>>>> IIUC, properties are set in this way:
>>>>
>>>> - on a file basis, before any heading, through the =PROPERTY= keyword,
>>>> - on a subtree basis, through the =PROPERTIES= block.
>>>>
>>>> My comprehension is that the =PROPERTY= keyword may not be used inside "trees",
>>>> and should be ignored if that would happen.
>>>
>>> While it is not normal usage, I think that it is legal for #+PROPERTY:
>>> lines (or #+Option: lines etc...) to appear inside of subtrees.
>>
>> I realize this is not especially a Babel question, but more a Org core
>> question...
>>
>> Thanks for your answer -- which generates a new one, though: what is then the
>> expected *semantics* of such a construct?
>>
>> There are at least 3 different views on such a construct: putting a PROPERTY
>> line inside a subtree...
>>
>> - ... resets some values from that point up to the end of the subtree
>> - ... resets some values from that point up to the end of the buffer
>> - ... defines some values which can have already been by the subtree
>>
>
> I agree this is murky and whatever behavior we want should be clearly
> thought out and documented in the manual.  I would argue that you missed
> another possible semantics, the simple semantics which are currently
> implemented in which a property line *anywhere* in a buffer sets a
> global property.
>
> Cheers,
>
>>
>> Best regards,
>>    Seb
>>
>>>> The following example shows that either:
>>>>
>>>> - I'm wrong to think so,
>>>> - there is a bug.
>>>>
>>>> What is the right assumption here?
>>>>
>>>> * Subtree
>>>>
>>>> Being located in a subtree, the following lines are ill-placed IMHO:
>>>>
>>>> #+PROPERTY: var  foo="Hello
>>>> #+PROPERTY: var+ world"
>>>>
>>>> Though, they're well taken into account:
>>>>
>>>> #+begin_src emacs-lisp
>>>>    foo
>>>> #+end_src
>>>>
>>>> #+results:
>>>> : Hello world
>>>>
>>>> These lines have even wiped the definition of =bar= (because of the use of =var=
>>>> without any =+=):
>>>>
>>>> #+begin_src emacs-lisp
>>>>    (+ foo bar)
>>>> #+end_src
>>>>
>>>> returns the error "Symbol's value as variable is void: bar."
>