Re: timezone.el patterns in emacs 19.34

[Hrvoje Niksic <hniksic@srce.hr>]

Ken Raeburn <raeburn@cygnus.com> writes:

> > it should be written in C.  It's not that hard to write, and the
> > speedup would measure by hundreds (all those regexps would become
> > unnecessary).
> 
> I'm not so sure about converting it to straight C; I could imagine
> wanting to change the supported format list someday, and wanting to do
> so easily -- i.e., without recompiling emacs.

I think it's a small price to pay for a big speedup of Summary buffer
building.  Emacs is not a particularly fast piece of software, and I
don't think we should miss things like this.  The speedup would be
enormous, really.

The extensibility is not lost, as this subr can be overridden with
whatever you like, including the old version.

> Besides, I think you'd probably wind up doing the regexp bit
> anyways, just at the C level.  These patterns don't have to match
> the *entire* string, just some substring.

I would do no regexp matching.  If I had to resort to regexps, then I
would rather leave it in Lisp, as it is.

> Now, if we can ignore or work around that substring issue (not a
> trivial issue, Gnus isn't the only user of that code), and require a
> match against the whole string, then using getdate.y might be a win.
> I understand it's supposed to be pretty comprehensive.

NO!  I hate getdate.y.  First, because of the `.y' thingie. :-)  Then,
there are copyright problems with it.  And, I'd like to have a fast
routine that matches those 7 or so format strings.  Nothing more,
nothing less.  If someone wants more -- the doors of Lisp are wide
open.  I opt for speed in this case.

-- 
Hrvoje Niksic <hniksic@srce.hr> | Student at FER Zagreb, Croatia
--------------------------------+--------------------------------
Oh lord won't you buy me a color TV...