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Re: elisp question

From: Vinicius Jose Latorre
Subject: Re: elisp question
Date: Fri, 11 May 2007 20:49:55 -0300
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv: Gecko/20070221 SeaMonkey/1.1.1

stan wrote:
Recently I had cause to go digging into ps-print.el (turned out to be
version problems in cygwin emacs) and I ran accross something I don't
understand. For the record I'm not by any means an elisp programmer but
I can usually at least read the code and do some simple things.

The line I don't think I understand is
(and (fboundp 'start-process) 0)

Actually that's a fragment of a larger expression. It looks to me like
this will always be nil. Is this some idiom I haven't seeen or is this
just a synonym fo nil?

No, this expression returns nil or 0 (zero).

It's evaluated as the 5th parameter (buffer) of call-process-region.

Typing  C-h f call-process-region RET, you can read:

If buffer is 0, `call-process-region' returns immediately with value nil.
     Otherwise it waits for program to terminate
     and returns a numeric exit status or a signal description string.

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