* bug#5371: Priority of different kind of local variable bindings
@ 2010-01-13 9:20 Lennart Borgman
2010-01-13 14:41 ` Stefan Monnier
0 siblings, 1 reply; 5+ messages in thread
From: Lennart Borgman @ 2010-01-13 9:20 UTC (permalink / raw)
To: emacs-pretest-bug
I can't find a description in the manual of the priority of different
kind of local variables. Can that please be added to the manual?
^ permalink raw reply [flat|nested] 5+ messages in thread
* bug#5371: Priority of different kind of local variable bindings
2010-01-13 9:20 bug#5371: Priority of different kind of local variable bindings Lennart Borgman
@ 2010-01-13 14:41 ` Stefan Monnier
2010-01-13 15:50 ` Lennart Borgman
0 siblings, 1 reply; 5+ messages in thread
From: Stefan Monnier @ 2010-01-13 14:41 UTC (permalink / raw)
To: Lennart Borgman; +Cc: 5371
> I can't find a description in the manual of the priority of different
> kind of local variables. Can that please be added to the manual?
What do you mean by "priority of different kind of local variables"?
Stefan
^ permalink raw reply [flat|nested] 5+ messages in thread* bug#5371: Priority of different kind of local variable bindings
2010-01-13 14:41 ` Stefan Monnier
@ 2010-01-13 15:50 ` Lennart Borgman
2010-01-13 18:45 ` Stefan Monnier
0 siblings, 1 reply; 5+ messages in thread
From: Lennart Borgman @ 2010-01-13 15:50 UTC (permalink / raw)
To: Stefan Monnier; +Cc: 5371
On Wed, Jan 13, 2010 at 3:41 PM, Stefan Monnier
<monnier@iro.umontreal.ca> wrote:
>> I can't find a description in the manual of the priority of different
>> kind of local variables. Can that please be added to the manual?
>
> What do you mean by "priority of different kind of local variables"?
I just meant which value is active at a certain point.
I saw a strange thing working with mumamo and the js.el problem, but I
have not understod yet. I have kind of solved it, but I don't know
why. Here is some code that perhaps is related. Look at the value at
"ff". Is not that a bit surprising?
(defun temp-var-display (where)
(message "%s temp-var: u=%s, b=%s d=%s" where
temp-var
(buffer-local-value 'temp-var (current-buffer))
(default-value 'temp-var)))
(defvar temp-var "global")
(set (make-local-variable 'temp-var) "buffer-1")
(temp-var-display "bb")
(with-temp-buffer
(set (make-local-variable 'temp-var) "buffer-2")
(temp-var-display "cc")
(let ((temp-var "let"))
(temp-var-display "dd")
(kill-local-variable 'temp-var)
(temp-var-display "ff"))
(temp-var-display "gg"))
(temp-var-display "hh")
(kill-local-variable 'temp-var)
(temp-var-display "ii")
bb temp-var: u=buffer-1, b=buffer-1 d=global
cc temp-var: u=buffer-2, b=buffer-2 d=global
dd temp-var: u=let, b=let d=global
ff temp-var: u=global, b=global d=global
gg temp-var: u=global, b=global d=global
hh temp-var: u=buffer-1, b=buffer-1 d=global
ii temp-var: u=global, b=global d=global
^ permalink raw reply [flat|nested] 5+ messages in thread* bug#5371: Priority of different kind of local variable bindings
2010-01-13 15:50 ` Lennart Borgman
@ 2010-01-13 18:45 ` Stefan Monnier
2010-01-13 18:50 ` Lennart Borgman
0 siblings, 1 reply; 5+ messages in thread
From: Stefan Monnier @ 2010-01-13 18:45 UTC (permalink / raw)
To: Lennart Borgman; +Cc: 5371
>> What do you mean by "priority of different kind of local variables"?
> I just meant which value is active at a certain point.
It's not based on priorities.
> (with-temp-buffer
> (set (make-local-variable 'temp-var) "buffer-2")
> (temp-var-display "cc")
> (let ((temp-var "let"))
> (temp-var-display "dd")
> (kill-local-variable 'temp-var)
> (temp-var-display "ff"))
The `let' binding affects the currently "active" slot, so in this case
it affects the buffer-local slot. So after kill-local-variable, this
binding is lost.
Note that mixing let-binding and buffer-local bindings is generally
discouraged. The only known reasonably sane semantics for such a mix is
when the variable is always buffer-local. If you mix `let' with
make-local-variable and kill-local-variable you're really asking
for trouble.
Stefan
^ permalink raw reply [flat|nested] 5+ messages in thread* bug#5371: Priority of different kind of local variable bindings
2010-01-13 18:45 ` Stefan Monnier
@ 2010-01-13 18:50 ` Lennart Borgman
0 siblings, 0 replies; 5+ messages in thread
From: Lennart Borgman @ 2010-01-13 18:50 UTC (permalink / raw)
To: Stefan Monnier; +Cc: 5371
On Wed, Jan 13, 2010 at 7:45 PM, Stefan Monnier
<monnier@iro.umontreal.ca> wrote:
>>> What do you mean by "priority of different kind of local variables"?
>> I just meant which value is active at a certain point.
>
> It's not based on priorities.
>
>> (with-temp-buffer
>> (set (make-local-variable 'temp-var) "buffer-2")
>> (temp-var-display "cc")
>
>> (let ((temp-var "let"))
>> (temp-var-display "dd")
>
>> (kill-local-variable 'temp-var)
>> (temp-var-display "ff"))
>
> The `let' binding affects the currently "active" slot, so in this case
> it affects the buffer-local slot. So after kill-local-variable, this
> binding is lost.
Ok, I see.
> Note that mixing let-binding and buffer-local bindings is generally
> discouraged. The only known reasonably sane semantics for such a mix is
> when the variable is always buffer-local. If you mix `let' with
> make-local-variable and kill-local-variable you're really asking
> for trouble.
I know ;-)
Is this explained somewhere (except for the code)?
^ permalink raw reply [flat|nested] 5+ messages in thread
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2010-01-13 9:20 bug#5371: Priority of different kind of local variable bindings Lennart Borgman
2010-01-13 14:41 ` Stefan Monnier
2010-01-13 15:50 ` Lennart Borgman
2010-01-13 18:45 ` Stefan Monnier
2010-01-13 18:50 ` Lennart Borgman
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