Re: [PATCH] Allow property retrieval before first heading?

From: Dan Davison <dandavison7@gmail.com>
To: emacs-orgmode@gnu.org
Subject: Re: [PATCH] Allow property retrieval before first heading?
Date: Sat, 12 Feb 2011 16:42:49 +0000	[thread overview]
Message-ID: <m1r5bdtd9y.fsf@94.197.159.103.threembb.co.uk> (raw)
In-Reply-To: <m1tyg9qkwg.fsf@94.197.159.103.threembb.co.uk> (Dan Davison's message of "Sat, 12 Feb 2011 16:26:23 +0000")

Dan Davison <dandavison7@gmail.com> writes:

> Currently (org-entry-get) throws an error if point is before the first
> heading. Is there a reason that this must be so? Org is too essential
> for headings to be obligatory!
>
> An example of when it would be useful to get properties is in a buffer
> containing src blocks but no headings (babel takes header args from Org
> properties). 

Hmm, for the record I was confused on that point; Eric already has a
workaround for the error to the effect that babel will take header args
from a #+PROPERTY line in a buffer with no headings. But my question
stands, as this error is a gotcha, requiring code like this

  (or (condition-case nil
	  (org-entry-get (point) header-arg t)
	(error nil))
      (cdr (assoc header-arg org-file-properties))))

Dan

> I make heavy use of such buffers as a scratch pad.
>
> I'm not sure to what extent speed is essential in these functions, and
> therefore unsure whether the calls to `org-before-first-heading-p' are
> acceptable.
>
> Dan
>
>     Allow properties to be retrieved before first heading in file.
>     
>     * lisp/org.el (org-entry-get): Don't look for a property drawer if we
>     are before the first heading in the file.
>     (org-entry-get-with-inheritance): Don't attempt to move up the tree if
>     we are before the first heading in the file. Also, enclose less of the
>     function in the save-excursion.
>
> diff --git a/lisp/org.el b/lisp/org.el
> index 0104007..a676ec4 100644
> --- a/lisp/org.el
> +++ b/lisp/org.el
> @@ -13567,7 +13567,8 @@ when a \"nil\" value can supersede a non-nil value higher up the hierarchy."
>  	  ;; We need a special property.  Use `org-entry-properties' to
>  	  ;; retrieve it, but specify the wanted property
>  	  (cdr (assoc property (org-entry-properties nil 'special property)))
> -	(let ((range (org-get-property-block)))
> +	(let ((range (unless (org-before-first-heading-p)
> +		       (org-get-property-block))))
>  	  (if (and range
>  		   (goto-char (car range))
>  		   (re-search-forward
> @@ -13680,6 +13681,7 @@ should be considered as undefined (this is the meaning of nil here).
>  However, if LITERAL-NIL is set, return the string value \"nil\" instead."
>    (move-marker org-entry-property-inherited-from nil)
>    (let (tmp)
> +    (unless (org-before-first-heading-p)
>      (save-excursion
>        (save-restriction
>  	(widen)
> @@ -13690,11 +13692,12 @@ However, if LITERAL-NIL is set, return the string value \"nil\" instead."
>  	      (move-marker org-entry-property-inherited-from (point))
>  	      (throw 'ex tmp))
>  	    (or (org-up-heading-safe) (throw 'ex nil)))))
> +      ))
>        (setq tmp (or tmp
>  		    (cdr (assoc property org-file-properties))
>  		    (cdr (assoc property org-global-properties))
>  		    (cdr (assoc property org-global-properties-fixed))))
> -      (if literal-nil tmp (org-not-nil tmp)))))
> +      (if literal-nil tmp (org-not-nil tmp))))
>  
>  (defvar org-property-changed-functions nil
>    "Hook called when the value of a property has changed.
>
>
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