ram-ashwin@YALE.ARPA (Ashwin Ram) (08/20/87)
It would be nice to have a LOAD variant that loaded a file only if it was not
already loaded. E.g., if you use a particular sub-system or package in two
different places, you don't want it reloaded.
REQUIRE is pretty close, but it checks features rather than loaded files, and
most people don't include PROVIDE forms in their packages (including many
files in the standard Emacs distribution. E.g., you can't do this with
MAILALIAS since it is a file that is autoloaded by name rather than by a
required feature.)
Since many functions are autoloaded by filename rather than by
requiring/providing a feature, it makes sense to have a MAYBE-LOAD or
REQUIRE-FILE or something (or perhaps a RELOAD-P argument to LOAD).
Or maybe AUTOLOAD should be redesigned to be feature-oriented instead of
file-oriented (E.g., (autoload function feature &optional file) to autoload
"function", you need to require "feature" (which you get from "file")). Or
maybe a AUTOLOAD-FEATURE. Or something.
-- Ashwin.
ARPA: Ram-Ashwin@cs.yale.edu
UUCP: {decvax,linus,seismo}!yale!Ram-Ashwin
BITNET: Ram@yalecsram-ashwin@YALE.ARPA (Ashwin Ram) (08/20/87)
You're right, I didn't state my point clearly. What I was trying to get at
was this. Suppose my "wonderful-function" used a set of other wonderful
functions that were part of a package. For example, suppose I wrote an
rmail-like package that used a bunch of rmail functions, plus defined some
new ones. Now, it would be nice if my package could just require the
original rmail file, rather than autoloading each of these functions from
that rmail file. If the rmail file doesn't provide a feature (I know rmail
does, but many files don't), this is hard to do. You can either autoload
each individual function you need (a pain), or you have to load the file (and
have it reloaded again if you need this file for another package too).
One simple solution would be to make each file automatically provide the name
of the file itself as one of the features it provides (in addition to
explicit provides in the file). Then you can easily require the file using
existing require/provide mechanisms (which by the way I think are really
neat).
A related point: I think:
(if (not (fboundp 'wonderful-function))
(require "wonderful-feature")) ; with optional wonderful-file
is a cleaner way to do autoloads than:
(if (not (fboundp 'wonderful-function))
(load "wonderful-file"))
Since require's filename defaults to the feature name, the former is strictly
more powerful than the latter. This gives you a way to do package
dependencies in a slightly nicer way than autoload does.
-- Ashwin.
ARPA: Ram-Ashwin@cs.yale.edu
UUCP: {decvax,linus,seismo}!yale!Ram-Ashwin
BITNET: Ram@yalecs