From: "Drew Adams" <drew.adams@oracle.com>
To: "'Perry Smith'" <pedzsan@gmail.com>, <gebser@mousecar.com>
Cc: 'GNU Emacs List' <help-gnu-emacs@gnu.org>
Subject: RE: canonical name ending "-p"
Date: Fri, 18 Mar 2011 11:31:37 -0700 [thread overview]
Message-ID: <84CBE66E993C47F5971F92D7E71B47E0@us.oracle.com> (raw)
In-Reply-To: <E7907DCE-F47F-478C-8106-8E7A8929A2EC@gmail.com>
> > Lots of things in elisp end in "-p"... is there some
> > particular meaning in this?
>
> I was told it means "predicate" long ago by the guy who
> introduced me to lisp and emacs.
Yes. It is an old Lisp idiom, not just Emacs Lisp.
> In Ruby, they use a '?' so they have 'blank?'
> -- but '?' isn't a legal character in a
> symbol so they append "p" for predicate.
This part is incorrect. `?' is perfectly legal in a Lisp symbol.
Put your cursor on a `?' char in Emacs Lisp mode and do `C-u C-x ='. You will
see this: "syntax: _ which means: symbol". Then try it:
(defun foo? () (forward-char 1))
[Unfortunately, vanilla Emacs completion treats `?' specially, so you'll need to
quote it using `C-q ?' if you want to use `C-h f' to get help on `foo?': `C-h
foo C-q ?']
> I'm curious if I have this right or not...
Yes, except for `?'.
next prev parent reply other threads:[~2011-03-18 18:31 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-18 17:39 canonical name ending "-p" ken
2011-03-18 18:11 ` Allan Gottlieb
2011-03-18 18:18 ` Perry Smith
2011-03-18 18:31 ` Drew Adams [this message]
2011-03-18 18:20 ` Tom Rauchenwald
2011-03-18 18:31 ` Drew Adams
[not found] ` <mailman.12.1300472466.7441.help-gnu-emacs@gnu.org>
2011-03-19 1:52 ` Stefan Monnier
[not found] <mailman.8.1300470004.7441.help-gnu-emacs@gnu.org>
2011-03-18 17:56 ` Pascal J. Bourguignon
2011-03-18 20:36 ` Evans Winner
2011-03-19 4:32 ` rusi
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