Re: iCalendar support: reply to invitations, sync to org

[David Engster <deng@randomsample.de>]

Jan Tatarik writes:
> On Wed, Apr 03 2013, David Engster wrote:
>> Jan, would you be interested in that? As you probably know, this would
>> require that you assign copyright of your code to the FSF and to sign
>> papers. Also, your code would need some changes to be compatible with
>> older Emacsen.
>
> My papers for emacs and gnus are already on file.

That's great.

> As far as making the code compatible, I would appreciate some guidance
> there. Not just wrt older Emacsen, but also regarding coding
> conventions, namespace, etc.

A good first read is the Appendix D.1 (Emacs Lisp Coding Conventions) in
the Emacs Lisp reference manual.

I haven't looked at your code in detail yet. But a first few comments:

The first and for you probably most frustrating problem is the
dependence on cl-lib, which is only available since 24.3. On older
Emacsen you only have 'cl', from which you're only allowed to use
macros, though (see the mentioned coding conventions for further
details). So I'm afraid you have to forgo the functions (but not macros)
you use from cl-lib. EIEIO is OK, though; Gnus provides a fallback
library for that on older Emacsen.

Your package is a bit complicated since it involves three things:
icalendar, Gnus and Org. Still, I think it would be preferable to have
everything in a single file with a single namespace 'gnus-calendar'.
Everything should be prefixed with that; this includes methods and
macros (like your currently used `with-decoded-handle'). If you think
that some of your stuff would better fit in the icalendar package, Org,
or somewhere else in Gnus, then we should try to get this in there.

Also, M-x checkdoc is very helpful. :-)

-David