From: Stefan Monnier <monnier@iro.umontreal.ca>
To: emacs-devel@gnu.org
Subject: Re: On removing some obsolete code from subr and core
Date: Mon, 07 Nov 2016 15:31:08 -0500 [thread overview]
Message-ID: <jwvy40vqbw7.fsf-monnier+gmane.emacs.devel@gnu.org> (raw)
In-Reply-To: 20161107200828.GA866@holos.localdomain
> you or someone else know better why the default-FOO variables might be
> needed again,
The only reason would be backward compatibility.
> or why they were implemented in the first place.
I'm pretty sure it's for historical reasons. I don't know those
reasons, tho. My guess goes as follows:
- First there were normal vars, and buffer-local vars
(e.g. buffer-file-name, major-mode).
- The two sets were disjoint.
- There was no `default-value' nor `set-default'.
- For those buffer-local vars where a default value was needed/made
sense, a separate variable was introduced with the convention to name
it `default-FOO'.
Later on appeared `default-value`, `make-local-variable`,
`make-variable-buffer-local`, ... which blurred the line between those
two disjoint sets of variables, at which point the `default-FOO' vars
became redundant but they were kept for backward compatibility reasons
(also it's occasionally handy to let-bind `default-FOO', while doing the
same for (default-value 'FOO) requires something like `cl-letf').
Stefan
next prev parent reply other threads:[~2016-11-07 20:31 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-04 16:59 On removing some obsolete code from subr and core Mark Oteiza
2016-11-05 8:24 ` John Wiegley
2016-11-05 8:34 ` Eli Zaretskii
2016-11-05 13:50 ` Mark Oteiza
2016-11-05 17:59 ` Eli Zaretskii
2016-11-06 16:58 ` Mark Oteiza
2016-11-05 17:50 ` Stefan Monnier
2016-11-06 17:05 ` Mark Oteiza
2016-11-06 22:32 ` Stefan Monnier
2016-11-07 0:32 ` Mark Oteiza
2016-11-07 3:35 ` Eli Zaretskii
2016-11-07 4:24 ` Mark Oteiza
2016-11-07 15:11 ` Eli Zaretskii
2016-11-07 20:08 ` Mark Oteiza
2016-11-07 20:13 ` Eli Zaretskii
2016-11-07 20:25 ` Mark Oteiza
2016-11-08 6:51 ` Noam Postavsky
2016-11-07 20:31 ` Stefan Monnier [this message]
2016-11-07 21:32 ` Johan Bockgård
2016-11-08 13:00 ` Stefan Monnier
2016-11-08 19:49 ` John Wiegley
2016-11-05 15:51 ` Clément Pit--Claudel
2016-11-05 15:52 ` Clément Pit--Claudel
2016-11-05 16:42 ` Dmitry Gutov
2016-11-05 17:23 ` Clément Pit--Claudel
2016-11-05 17:31 ` Dmitry Gutov
2016-11-05 18:03 ` Clément Pit--Claudel
2016-11-05 15:57 ` Clément Pit--Claudel
2016-11-05 17:56 ` Stefan Monnier
2016-11-05 19:14 ` Clément Pit--Claudel
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