From: "Drew Adams" <drew.adams@oracle.com>
Subject: defcustom :type (file :must-match t)
Date: Tue, 20 Dec 2005 15:21:16 -0800 [thread overview]
Message-ID: <MEEKKIABFKKDFJMPIOEBAEBFCOAA.drew.adams@oracle.com> (raw)
I don't understand the customization type `(file :must-match t)'. The Elisp
manual says only this: "The value must be a file name for an existing file,
and you can do completion with `M-<TAB>'."
I don't see where/when/how this existence criterion is enforced. At what
point is it checked and an error raised if you try to use a name that
corresponds to no file?
I am able to create a defcustom with a file name (with complete path) that
does not correspond to an existing file. I am able to customize the file
name in Customize, providing a name that doesn't correspond to an existing
file. I am able to set for the current session and even save such a nonsense
value.
So, in what sense _must_ the file-name value be the name of an existing
file? What am I missing?
The last phrase is, in any case, unclear: "and you can do completion with
`M-<TAB>'"? When/where can you do this? Does this mean in Customize, when
"you" are typing a new file name? With `set-variable' also? When "you" are
typing the defcustom? The Elisp manual is for programmers, and this section
of the manual tells "you" how to define a file-name :type, so I would guess
that the "you" here is not an end user of Customize but a programmer writing
a defcustom. But trial and error shows that "you" is the Customize end user,
and only Customize is meant, not also `set-variable'. This should be cleared
up.
If the only "must" check for existence is that provided by file-name
completion (e.g. REQUIRE-MATCH arg to `completing-read'), then this whole
entry should be rewritten to say that. Currently, it gives the impression
that `:type (file :must-match t)' will somehow, somewhere, somewhen, force
users to use file names that correspond to existing files.
next reply other threads:[~2005-12-20 23:21 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-20 23:21 Drew Adams [this message]
2005-12-20 23:56 ` defcustom :type (file :must-match t) Luc Teirlinck
2005-12-21 0:12 ` Drew Adams
2005-12-21 4:08 ` Luc Teirlinck
2005-12-21 4:37 ` Luc Teirlinck
2005-12-21 5:06 ` Luc Teirlinck
2005-12-21 18:52 ` Richard M. Stallman
2005-12-22 2:07 ` Luc Teirlinck
2005-12-21 19:29 ` :must-match and set-variable (was: Re: defcustom :type (file :must-match t)) Stuart D. Herring
2005-12-24 20:12 ` :must-match and set-variable Juri Linkov
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