@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990-1995, 1998-2014 Free Software Foundation, Inc.
+@c Copyright (C) 1990-1995, 1998-2016 Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@node Variables
@chapter Variables
@menu
* Global Variables:: Variable values that exist permanently, everywhere.
-* Constant Variables:: Certain "variables" have values that never change.
+* Constant Variables:: Variables that never change.
* Local Variables:: Variable values that exist only temporarily.
* Void Variables:: Symbols that lack values.
* Defining Variables:: A definition says a symbol is used as a variable.
@code{nil} otherwise.
@end defun
-These constants are fundamentally different from the ``constants''
+These constants are fundamentally different from the constants
defined using the @code{defconst} special form (@pxref{Defining
Variables}). A @code{defconst} form serves to inform human readers
that you do not intend to change the value of a variable, but Emacs
and it is the binding acted on by @code{setq}.
For most purposes, you can think of the current binding as the
-``innermost'' local binding, or the global binding if there is no
+innermost local binding, or the global binding if there is no
local binding. To be more precise, a rule called the @dfn{scoping
rule} determines where in a program a local binding takes effect. The
default scoping rule in Emacs Lisp is called @dfn{dynamic scoping},
Variables}); a few variables have terminal-local bindings
(@pxref{Multiple Terminals}). These kinds of bindings work somewhat
like ordinary local bindings, but they are localized depending on
-``where'' you are in Emacs.
+where you are in Emacs.
@defopt max-specpdl-size
@anchor{Definition of max-specpdl-size}
@end defopt
@node Void Variables
-@section When a Variable is ``Void''
+@section When a Variable is Void
@cindex @code{void-variable} error
@cindex void variable
@item @dots{}-predicate
The value is a predicate---a function of one argument that returns
-non-@code{nil} for ``good'' arguments and @code{nil} for ``bad''
-arguments.
+non-@code{nil} for success and @code{nil} for failure.
@item @dots{}-flag
The value is significant only as to whether it is @code{nil} or not.
@end table
When you define a variable, always consider whether you should mark
-it as ``safe'' or ``risky''; see @ref{File Local Variables}.
+it as safe or risky; see @ref{File Local Variables}.
When defining and initializing a variable that holds a complicated
value (such as a keymap with bindings in it), it's best to put the
(defvar x -99) ; @r{@code{x} receives an initial value of @minus{}99.}
(defun getx ()
- x) ; @r{@code{x} is used ``free'' in this function.}
+ x) ; @r{@code{x} is used free in this function.}
(let ((x 1)) ; @r{@code{x} is dynamically bound.}
(getx))
@end example
@noindent
-The function @code{getx} refers to @code{x}. This is a ``free''
+The function @code{getx} refers to @code{x}. This is a @dfn{free}
reference, in the sense that there is no binding for @code{x} within
that @code{defun} construct itself. When we call @code{getx} from
within a @code{let} form in which @code{x} is (dynamically) bound, it
@result{} 4
(defun getx ()
- x) ; @r{@code{x} is used ``free'' in this function.}
+ x) ; @r{@code{x} is used free in this function.}
(let ((x 1)) ; @r{@code{x} is lexically bound.}
(getx))
A simple way to find out which variables need a variable definition
is to byte-compile the source file. @xref{Byte Compilation}. If a
non-special variable is used outside of a @code{let} form, the
-byte-compiler will warn about reference or assignment to a ``free
-variable''. If a non-special variable is bound but not used within a
-@code{let} form, the byte-compiler will warn about an ``unused lexical
-variable''. The byte-compiler will also issue a warning if you use a
+byte-compiler will warn about reference or assignment to a free
+variable. If a non-special variable is bound but not used within a
+@code{let} form, the byte-compiler will warn about an unused lexical
+variable. The byte-compiler will also issue a warning if you use a
special variable as a function argument.
(To silence byte-compiler warnings about unused variables, just use
buffer-local variables interactively.
@end deffn
+@cindex local variables, killed by major mode
@defun kill-all-local-variables
This function eliminates all the buffer-local variable bindings of the
-current buffer except for variables marked as ``permanent'' and local
+current buffer except for variables marked as permanent and local
hook functions that have a non-@code{nil} @code{permanent-local-hook}
property (@pxref{Setting Hooks}). As a result, the buffer will see
the default values of most variables.
to use this, @pxref{Auto Major Mode}.
@end defvar
-@defun hack-local-variables &optional mode-only
+@defun hack-local-variables &optional handle-mode
This function parses, and binds or evaluates as appropriate, any local
variables specified by the contents of the current buffer. The variable
@code{enable-local-variables} has its effect here. However, this
function ignores a @samp{mode} element if it specifies the same major
mode as the buffer already has.
-If the optional argument @var{mode-only} is non-@code{nil}, then all
-this function does is return a symbol specifying the major mode,
-if the @w{@samp{-*-}} line or the local variables list specifies one,
-and @code{nil} otherwise. It does not set the mode nor any other
-file-local variable.
+If the optional argument @var{handle-mode} is @code{t}, then all this
+function does is return a symbol specifying the major mode, if the
+@w{@samp{-*-}} line or the local variables list specifies one, and
+@code{nil} otherwise. It does not set the mode or any other
+file-local variable. If @var{handle-mode} has any value other than
+@code{nil} or @code{t}, any settings of @samp{mode} in the
+@w{@samp{-*-}} line or the local variables list are ignored, and the
+other settings are applied. If @var{handle-mode} is @code{nil}, all
+the file local variables are set.
@end defun
@defvar file-local-variables-alist
string).
The optional argument @var{access-type}, if non-@code{nil}, should
-should specify the kind of access that will trigger obsolescence
-warnings; it can be either @code{get} or @code{set}.
+specify the kind of access that will trigger obsolescence warnings; it
+can be either @code{get} or @code{set}.
@end defun
You can make two variables synonyms and declare one obsolete at the
of arrays, properties of symbols, and many other locations are also
places where Lisp values are stored.
-Generalized variables are analogous to ``lvalues'' in the C
+Generalized variables are analogous to lvalues in the C
language, where @samp{x = a[i]} gets an element from an array
and @samp{a[i] = x} stores an element using the same notation.
Just as certain forms like @code{a[i]} can be lvalues in C, there
A call to any of the following Emacs-specific functions:
@smallexample
-default-value process-get
+alist-get process-get
frame-parameter process-sentinel
terminal-parameter window-buffer
keymap-parent window-display-table
overlay-start window-parameter
overlay-end window-point
process-buffer window-start
-process-filter
+process-filter default-value
@end smallexample
@end itemize
@cindex CL note---no @code{setf} functions
@quotation
@b{Common Lisp note:} Common Lisp defines another way to specify the
-@code{setf} behavior of a function, namely ``@code{setf} functions'',
+@code{setf} behavior of a function, namely @code{setf} functions,
whose names are lists @code{(setf @var{name})} rather than symbols.
For example, @code{(defun (setf foo) @dots{})} defines the function
that is used when @code{setf} is applied to @code{foo}. Emacs does