The buffer-local value of variable starts out as the same value variable previously had. If variable was void, it remains void.
;; In buffer `b1': (setq foo 5) ; Affects all buffers. => 5 (make-local-variable 'foo) ; Now it is local in `b1'. => foo foo ; That did not change => 5 ; the value. (setq foo 6) ; Change the value => 6 ; in `b1'. foo => 6 ;; In buffer `b2', the value hasn't changed. (save-excursion (set-buffer "b2") foo) => 5
Making a variable buffer-local within a let
-binding for that
variable does not work. This is because let
does not distinguish
between different kinds of bindings; it knows only which variable the
binding was made for.
If the variable is terminal-local, this function signals an error. Such variables cannot have buffer-local bindings as well. See section Multiple Displays.
Note: do not use make-local-variable
for a hook
variable. Instead, use make-local-hook
. See section Hooks.
The value returned is variable.
Note: It is a mistake to use make-variable-buffer-local
for user-option variables, simply because users might want to
customize them differently in different buffers. Users can make any
variable local, when they wish to.
The main use of make-variable-buffer-local
is when a variable is
used for internal purposes, and the Lisp program depends on having
separate values in separate buffers.
t
if variable is buffer-local in buffer
buffer (which defaults to the current buffer); otherwise,
nil
.
(make-local-variable 'foobar) (makunbound 'foobar) (make-local-variable 'bind-me) (setq bind-me 69) (setq lcl (buffer-local-variables)) ;; First, built-in variables local in all buffers: => ((mark-active . nil) (buffer-undo-list nil) (mode-name . "Fundamental") ... ;; Next, non-built-in local variables. ;; This one is local and void: foobar ;; This one is local and nonvoid: (bind-me . 69))
Note that storing new values into the CDRs of cons cells in this list does not change the local values of the variables.
If you kill the local binding of a variable that automatically becomes local when set, this makes the global value visible in the current buffer. However, if you set the variable again, that will once again create a local binding for it.
kill-local-variable
returns variable.
This function is a command because it is sometimes useful to kill one buffer-local variable interactively, just as it is useful to create buffer-local variables interactively.
This function also resets certain other information pertaining to the
buffer: it sets the local keymap to nil
, the syntax table to the
value of standard-syntax-table
, and the abbrev table to the value
of fundamental-mode-abbrev-table
.
Every major mode command begins by calling this function, which has the effect of switching to Fundamental mode and erasing most of the effects of the previous major mode. To ensure that this does its job, the variables that major modes set should not be marked permanent.
kill-all-local-variables
returns nil
.
A local variable is permanent if the variable name (a symbol) has a
permanent-local
property that is non-nil
. Permanent
locals are appropriate for data pertaining to where the file came from
or how to save it, rather than with how to edit the contents.
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