Re: Problems with (defvar foo) and Emacs 23

[Nick Dokos <nicholas.dokos@hp.com>]

Bernt Hansen <bernt@norang.ca> wrote:

> Hi Bastien,
> 
> I updated to master today e917477 ((org-xhtml.el): Removed, 2012-04-01)
> and am getting errors about org-clock-last-state not defined in my GNU
> Emacs 23.2.1 (i486-pc-linux-gnu, GTK+ Version 2.20.0) of 2010-12-11 on
> raven, modified by Debian
> 
> I can see the variable in the source defined as
> 
> lisp/org-clock.el:(defvar org-clock-state) ;; dynamically scoped into this function
> 
> but I don't get a variable definition with this code in emacs 23.2.1.
> 
> If I change the definition to
> 
> (defvar org-clock-state nil)
> 
> then it works for me.
> 
> There are _lots_ of these types of definitions with no value in the
> org-mode source.
> 

They are not supposed to *define* a variable. They are there to tell the
compiler not to worry. They are somewhat similar[fn:1] to extern declarations
in C code: whoever needs to use the variable says

  (defvar foo)

There is (supposed to be) *one* place somewhere that actually defines
it:

  (defvar foo 1)

Nick

Footnotes:

[fn:1] ...for some value of "similar". You have to take this with the
appropriately sized grain of salt.