From: Michael Ekstrand <michael@elehack.net>
To: help-gnu-emacs@gnu.org
Subject: Re: how to check if xyz-mode is on load path?
Date: Mon, 02 Mar 2009 07:12:47 -0600 [thread overview]
Message-ID: <87fxhwhxv4.fsf@jehiel.elehack.net> (raw)
In-Reply-To: bde06bf6-9a89-404d-b2d9-cd04c1730b85@k36g2000pri.googlegroups.com
Xah Lee <xahlee@gmail.com> writes:
> how can i check if a package already exists in the load path?
>
> what i want to do is to put a package into autoload, but don't do that
> if that package is already included in user's load path (e.g. either
> the package is included in the emacs version she's got, or she already
> installed it herself).
>
> e.g. pseudo code:
>
> (when
> (not (isPackageInstalledQ "ocaml-mode"))
> (autoload ocaml-mode "~/xahdir/ocaml-mode" )
> )
locate-library will tell you if the library is available on the load
path; it will return a file name or nil. featurep (on the package's
primary provided feature) or fboundp (on some relevant function's
symbol) can be used to test if it has already been loaded.
I would also pair the tests such that locate-library failing results in
the package being added to the load path, and featurep/fboundp results
in loading. The package existing in the load path does not mean it has
been loaded/autoloaded, so just testing with locate-library in your code
above can result in the package not being loaded.
- Michael
--
mouse, n: A device for pointing at the xterm in which you want to type.
Confused by the strange files? I cryptographically sign my messages.
For more information see <http://www.elehack.net/resources/gpg>.
next prev parent reply other threads:[~2009-03-02 13:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-02 4:48 how to check if xyz-mode is on load path? Xah Lee
2009-03-02 6:08 ` B. T. Raven
2009-03-02 10:03 ` Lennart Borgman
2009-03-02 13:12 ` Michael Ekstrand [this message]
2009-03-02 13:15 ` Alan Mackenzie
2009-03-02 14:25 ` Kevin Rodgers
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