(Searching and Matching): Move node.

[gnu-emacs] / lispref / variables.texi

diff --git a/lispref/variables.texi b/lispref/variables.texi
index ab5e99e506c86cbfbeb2e68dbe9dcb6f945af4f0..1f26b56db8f6d78f14abb632da93f06d02efb5ce 100644 (file)
--- a/lispref/variables.texi
+++ b/lispref/variables.texi
@@ -1,7 +1,7 @@
 @c -*-texinfo-*-
 @c This is part of the GNU Emacs Lisp Reference Manual.
 @c -*-texinfo-*-
 @c This is part of the GNU Emacs Lisp Reference Manual.

-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2000
-@c   Free Software Foundation, Inc.
+@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2000, 2002,
+@c   2003, 2004, 2005 Free Software Foundation, Inc.

 @c See the file elisp.texi for copying conditions.
 @setfilename ../info/variables
 @node Variables, Functions, Control Structures, Top
 @c See the file elisp.texi for copying conditions.
 @setfilename ../info/variables
 @node Variables, Functions, Control Structures, Top


@@ -41,8 +41,10 @@ variable.
 * Buffer-Local Variables::  Variable values in effect only in one buffer.
 * Frame-Local Variables::   Variable values in effect only in one frame.
 * Future Local Variables::  New kinds of local values we might add some day.
 * Buffer-Local Variables::  Variable values in effect only in one buffer.
 * Frame-Local Variables::   Variable values in effect only in one frame.
 * Future Local Variables::  New kinds of local values we might add some day.

-* Variable Aliases::      Variables that are aliases for other variables.

 * File Local Variables::  Handling local variable lists in files.
 * File Local Variables::  Handling local variable lists in files.

+* Variable Aliases::      Variables that are aliases for other variables.
+* Variables with Restricted Values::  Non-constant variables whose value can
+                                        @emph{not} be an arbitrary Lisp object.

 @end menu
 
 @node Global Variables
 @end menu
 
 @node Global Variables


@@ -259,18 +261,20 @@ they are localized depending on ``where'' you are in Emacs, rather than
 localized in time.
 
 @defvar max-specpdl-size
 localized in time.
 
 @defvar max-specpdl-size

+@anchor{Definition of max-specpdl-size}

 @cindex variable limit error
 @cindex evaluation error
 @cindex infinite recursion
 This variable defines the limit on the total number of local variable
 @cindex variable limit error
 @cindex evaluation error
 @cindex infinite recursion
 This variable defines the limit on the total number of local variable

-bindings and @code{unwind-protect} cleanups (@pxref{Nonlocal Exits})
-that are allowed before signaling an error (with data @code{"Variable
-binding depth exceeds max-specpdl-size"}).
+bindings and @code{unwind-protect} cleanups (@pxref{Cleanups,,
+Cleaning Up from Nonlocal Exits}) that are allowed before signaling an
+error (with data @code{"Variable binding depth exceeds
+max-specpdl-size"}).

 
 This limit, with the associated error when it is exceeded, is one way
 that Lisp avoids infinite recursion on an ill-defined function.
 @code{max-lisp-eval-depth} provides another limit on depth of nesting.
 
 This limit, with the associated error when it is exceeded, is one way
 that Lisp avoids infinite recursion on an ill-defined function.
 @code{max-lisp-eval-depth} provides another limit on depth of nesting.

-@xref{Eval}.
+@xref{Definition of max-lisp-eval-depth,, Eval}.

 
 The default value is 600.  Entry to the Lisp debugger increases the
 value, if there is little room left, to make sure the debugger itself
 
 The default value is 600.  Entry to the Lisp debugger increases the
 value, if there is little room left, to make sure the debugger itself


@@ -518,7 +522,7 @@ The @code{defvar} form returns @var{symbol}, but it is normally used
 at top level in a file where its value does not matter.
 @end defspec
 
 at top level in a file where its value does not matter.
 @end defspec
 

-@defspec defconst symbol [value [doc-string]]
+@defspec defconst symbol value [doc-string]

 This special form defines @var{symbol} as a value and initializes it.
 It informs a person reading your code that @var{symbol} has a standard
 global value, established here, that should not be changed by the user
 This special form defines @var{symbol} as a value and initializes it.
 It informs a person reading your code that @var{symbol} has a standard
 global value, established here, that should not be changed by the user


@@ -526,10 +530,10 @@ or by other programs.  Note that @var{symbol} is not evaluated; the
 symbol to be defined must appear explicitly in the @code{defconst}.
 
 @code{defconst} always evaluates @var{value}, and sets the value of
 symbol to be defined must appear explicitly in the @code{defconst}.
 
 @code{defconst} always evaluates @var{value}, and sets the value of

-@var{symbol} to the result if @var{value} is given.  If @var{symbol}
-does have a buffer-local binding in the current buffer, @code{defconst}
-sets the default value, not the buffer-local value.  (But you should not
-be making buffer-local bindings for a symbol that is defined with
+@var{symbol} to the result.  If @var{symbol} does have a buffer-local
+binding in the current buffer, @code{defconst} sets the default value,
+not the buffer-local value.  (But you should not be making
+buffer-local bindings for a symbol that is defined with

 @code{defconst}.)
 
 Here, @code{pi} is a constant that presumably ought not to be changed
 @code{defconst}.)
 
 Here, @code{pi} is a constant that presumably ought not to be changed


@@ -564,7 +568,7 @@ though being declared using @code{defcustom}@footnote{They may also be
 declared equivalently in @file{cus-start.el}.} or by the first character
 of their @code{variable-documentation} property.  If the property exists
 and is a string, and its first character is @samp{*}, then the variable
 declared equivalently in @file{cus-start.el}.} or by the first character
 of their @code{variable-documentation} property.  If the property exists
 and is a string, and its first character is @samp{*}, then the variable

-is a user option.
+is a user option.  Aliases of user options are also user options.

 @end defun
 
 @kindex variable-interactive
 @end defun
 
 @kindex variable-interactive


@@ -858,11 +862,16 @@ always affects the most local existing binding.
   One other function for setting a variable is designed to add
 an element to a list if it is not already present in the list.
 
   One other function for setting a variable is designed to add
 an element to a list if it is not already present in the list.
 

-@defun add-to-list symbol element
+@defun add-to-list symbol element &optional append

 This function sets the variable @var{symbol} by consing @var{element}
 onto the old value, if @var{element} is not already a member of that
 value.  It returns the resulting list, whether updated or not.  The
 value of @var{symbol} had better be a list already before the call.
 This function sets the variable @var{symbol} by consing @var{element}
 onto the old value, if @var{element} is not already a member of that
 value.  It returns the resulting list, whether updated or not.  The
 value of @var{symbol} had better be a list already before the call.

+Membership is tested using @code{equal}.
+
+Normally, if @var{element} is added, it is added to the front of
+@var{symbol}, but if the optional argument @var{append} is
+non-@code{nil}, it is added at the end.

 
 The argument @var{symbol} is not implicitly quoted; @code{add-to-list}
 is an ordinary function, like @code{set} and unlike @code{setq}.  Quote
 
 The argument @var{symbol} is not implicitly quoted; @code{add-to-list}
 is an ordinary function, like @code{set} and unlike @code{setq}.  Quote


@@ -893,6 +902,62 @@ foo                       ;; @r{@code{foo} was changed.}
     (setq @var{var} (cons @var{value} @var{var})))
 @end example
 
     (setq @var{var} (cons @var{value} @var{var})))
 @end example
 

+@defun add-to-ordered-list symbol element &optional order
+This function sets the variable @var{symbol} by inserting
+@var{element} into the old value, which must be a list, at the
+position specified by @var{order}.  If @var{element} is already a
+member of the list, its position in the list is adjusted according
+to @var{order}.  Membership is tested using @code{eq}.
+This function returns the resulting list, whether updated or not.
+
+The @var{order} is typically a number (integer or float), and the
+elements of the list are sorted in non-decreasing numerical order.
+
+@var{order} may also be omitted or @code{nil}.  Then the numeric order
+of @var{element} stays unchanged if it already has one; otherwise,
+@var{element} has no numeric order.  Elements without a numeric list
+order are placed at the end of the list, in no particular order.
+
+Any other value for @var{order} removes the numeric order of @var{element}
+if it already has one; otherwise, it is equivalent to @code{nil}.
+
+The argument @var{symbol} is not implicitly quoted;
+@code{add-to-ordered-list} is an ordinary function, like @code{set}
+and unlike @code{setq}.  Quote the argument yourself if that is what
+you want.
+
+The ordering information is stored in a hash table on @var{symbol}'s
+@code{list-order} property.
+@end defun
+
+Here's a scenario showing how to use @code{add-to-ordered-list}:
+
+@example
+(setq foo '())
+     @result{} nil
+
+(add-to-ordered-list 'foo 'a 1)     ;; @r{Add @code{a}.}
+     @result{} (a)
+
+(add-to-ordered-list 'foo 'c 3)     ;; @r{Add @code{c}.}
+     @result{} (a c)
+
+(add-to-ordered-list 'foo 'b 2)     ;; @r{Add @code{b}.}
+     @result{} (a b c)
+
+(add-to-ordered-list 'foo 'b 4)     ;; @r{Move @code{b}.}
+     @result{} (a c b)
+
+(add-to-ordered-list 'foo 'd)       ;; @r{Append @code{d}.}
+     @result{} (a c b d)
+
+(add-to-ordered-list 'foo 'e)       ;; @r{Add @code{e}}.
+     @result{} (a c b e d)
+
+foo                       ;; @r{@code{foo} was changed.}
+     @result{} (a c b e d)
+@end example
+

 @node Variable Scoping
 @section Scoping Rules for Variable Bindings
 
 @node Variable Scoping
 @section Scoping Rules for Variable Bindings
 


@@ -904,6 +969,7 @@ the others.
 @cindex scope
 @cindex extent
 @cindex dynamic scoping
 @cindex scope
 @cindex extent
 @cindex dynamic scoping

+@cindex lexical scoping

   Local bindings in Emacs Lisp have @dfn{indefinite scope} and
 @dfn{dynamic extent}.  @dfn{Scope} refers to @emph{where} textually in
 the source code the binding can be accessed.  ``Indefinite scope'' means
   Local bindings in Emacs Lisp have @dfn{indefinite scope} and
 @dfn{dynamic extent}.  @dfn{Scope} refers to @emph{where} textually in
 the source code the binding can be accessed.  ``Indefinite scope'' means


@@ -1295,7 +1361,14 @@ local to the current buffer at the time.
 A peculiar wrinkle of this feature is that binding the variable (with
 @code{let} or other binding constructs) does not create a buffer-local
 binding for it.  Only setting the variable (with @code{set} or
 A peculiar wrinkle of this feature is that binding the variable (with
 @code{let} or other binding constructs) does not create a buffer-local
 binding for it.  Only setting the variable (with @code{set} or

-@code{setq}) does so.
+@code{setq}), while the variable does not have a @code{let}-style
+binding that was made in the current buffer, does so.
+
+If @var{variable} does not have a default value, then calling this
+command will give it a default value of @code{nil}.  If @var{variable}
+already has a default value, that value remains unchanged.
+Subsequently calling @code{makunbound} on @var{variable} will result
+in a void buffer-local value and leave the default value unaffected.

 
 The value returned is @var{variable}.
 
 
 The value returned is @var{variable}.
 


@@ -1318,6 +1391,12 @@ This returns @code{t} if @var{variable} is buffer-local in buffer
 @code{nil}.
 @end defun
 
 @code{nil}.
 @end defun
 

+@defun local-variable-if-set-p variable &optional buffer
+This returns @code{t} if @var{variable} will become buffer-local in
+buffer @var{buffer} (which defaults to the current buffer) if it is
+set there.
+@end defun
+

 @defun buffer-local-value variable buffer
 This function returns the buffer-local binding of @var{variable} (a
 symbol) in buffer @var{buffer}.  If @var{variable} does not have a
 @defun buffer-local-value variable buffer
 This function returns the buffer-local binding of @var{variable} (a
 symbol) in buffer @var{buffer}.  If @var{variable} does not have a


@@ -1405,8 +1484,11 @@ variables that major modes set should not be marked permanent.
 The function @code{kill-all-local-variables} runs this normal hook
 before it does anything else.  This gives major modes a way to arrange
 for something special to be done if the user switches to a different
 The function @code{kill-all-local-variables} runs this normal hook
 before it does anything else.  This gives major modes a way to arrange
 for something special to be done if the user switches to a different

-major mode.  For best results, make this variable buffer-local, so that
-it will disappear after doing its job and will not interfere with the
+major mode.  It is also useful for buffer-specific minor modes
+that should be forgotten if the user changes the major mode.
+
+For best results, make this variable buffer-local, so that it will
+disappear after doing its job and will not interfere with the

 subsequent major mode.  @xref{Hooks}.
 @end defvar
 
 subsequent major mode.  @xref{Hooks}.
 @end defvar
 


@@ -1555,11 +1637,17 @@ not in itself create any frame-local bindings for the variable; however,
 if some frame already has a value for @var{variable} as a frame
 parameter, that value automatically becomes a frame-local binding.
 
 if some frame already has a value for @var{variable} as a frame
 parameter, that value automatically becomes a frame-local binding.
 

+If @var{variable} does not have a default value, then calling this
+command will give it a default value of @code{nil}.  If @var{variable}
+already has a default value, that value remains unchanged.
+

 If the variable is terminal-local, this function signals an error,
 because such variables cannot have frame-local bindings as well.
 @xref{Multiple Displays}.  A few variables that are implemented
 specially in Emacs can be (and usually are) buffer-local, but can never
 be frame-local.
 If the variable is terminal-local, this function signals an error,
 because such variables cannot have frame-local bindings as well.
 @xref{Multiple Displays}.  A few variables that are implemented
 specially in Emacs can be (and usually are) buffer-local, but can never
 be frame-local.

+
+This command returns @var{variable}.

 @end deffn
 
   Buffer-local bindings take precedence over frame-local bindings.  Thus,
 @end deffn
 
   Buffer-local bindings take precedence over frame-local bindings.  Thus,


@@ -1655,6 +1743,92 @@ bindings offer a way to handle these situations more robustly.
   If sufficient application is found for either of these two kinds of
 local bindings, we will provide it in a subsequent Emacs version.
 
   If sufficient application is found for either of these two kinds of
 local bindings, we will provide it in a subsequent Emacs version.
 

+@node File Local Variables
+@section File Local Variables
+
+  This section describes the functions and variables that affect
+processing of file local variables.  @xref{File variables, ,
+Local Variables in Files, emacs, The GNU Emacs Manual}, for basic
+information about file local variables.
+
+@defopt enable-local-variables
+This variable controls whether to process file local variables.  A
+value of @code{t} means process them unconditionally; @code{nil} means
+ignore them; anything else means ask the user what to do for each
+file.  The default value is @code{t}.
+@end defopt
+
+@defun hack-local-variables &optional mode-only
+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 does not look for the @samp{mode:} local variable in the
+@w{@samp{-*-}} line.  @code{set-auto-mode} does that, also taking
+@code{enable-local-variables} into account (@pxref{Auto Major Mode}).
+
+If the optional argument @var{mode-only} is non-@code{nil}, then all
+this function does is return @code{t} if the @w{@samp{-*-}} line or
+the local variables list specifies a mode and @code{nil} otherwise.
+It does not set the mode nor any other file local variable.
+@end defun
+
+  If a file local variable could specify a function that would
+be called later, or an expression that would be executed later, simply
+visiting a file could take over your Emacs.  To prevent this, Emacs
+takes care not to allow to set such file local variables.
+
+  For one thing, any variable whose name ends in any of
+@samp{-command}, @samp{-frame-alist}, @samp{-function},
+@samp{-functions}, @samp{-hook}, @samp{-hooks}, @samp{-form},
+@samp{-forms}, @samp{-map}, @samp{-map-alist}, @samp{-mode-alist},
+@samp{-program}, or @samp{-predicate} cannot be given a file local
+value.  In general, you should use such a name whenever it is
+appropriate for the variable's meaning.  The variables
+@samp{font-lock-keywords}, @samp{font-lock-keywords} followed by a
+digit, and @samp{font-lock-syntactic-keywords} cannot be given file
+local values either.  These rules can be overridden by giving the
+variable's name a non-@code{nil} @code{safe-local-variable} property.
+If one gives it a @code{safe-local-variable} property of @code{t},
+then one can give the variable any file local value.  One can also
+give any symbol, including the above, a @code{safe-local-variable}
+property that is a function taking exactly one argument.  In that
+case, giving a variable with that name a file local value is only
+allowed if the function returns non-@code{nil} when called with that
+value as argument.
+
+  In addition, any variable whose name has a non-@code{nil}
+@code{risky-local-variable} property is also ignored.  So are all
+variables listed in @code{ignored-local-variables}:
+
+@defvar ignored-local-variables
+This variable holds a list of variables that should not be given local
+values by files.  Any value specified for one of these variables is
+ignored.
+@end defvar
+
+@defun risky-local-variable-p sym &optional val
+If @var{val} is non-@code{nil}, returns non-@code{nil} if giving
+@var{sym} a file local value of @var{val} would be risky, for any of
+the reasons stated above.  If @var{val} is @code{nil} or omitted, only
+returns @code{nil} if @var{sym} can be safely assigned any file local
+value whatsoever.
+@end defun
+
+  The @samp{Eval:} ``variable'' is also a potential loophole, so Emacs
+normally asks for confirmation before handling it.
+
+@defopt enable-local-eval
+This variable controls processing of @samp{Eval:} in @samp{-*-} lines
+or local variables
+lists in files being visited.  A value of @code{t} means process them
+unconditionally; @code{nil} means ignore them; anything else means ask
+the user what to do for each file.  The default value is @code{maybe}.
+@end defopt
+
+  Text properties are also potential loopholes, since their values
+could include functions to call.  So Emacs discards all text
+properties from string values specified for file local variables.
+

 @node Variable Aliases
 @section Variable Aliases
 
 @node Variable Aliases
 @section Variable Aliases
 


@@ -1666,21 +1840,59 @@ chosen, or because its meaning has partly changed---it can be useful
 to keep the old name as an @emph{alias} of the new one for
 compatibility.  You can do this with @code{defvaralias}.
 
 to keep the old name as an @emph{alias} of the new one for
 compatibility.  You can do this with @code{defvaralias}.
 

-@defun defvaralias alias-var base-var &optional docstring
-This function defines the symbol @var{alias-var} as a variable alias
-for symbol @var{base-var}. This means that retrieving the value of
-@var{alias-var} returns the value of @var{base-var}, and changing the
-value of @var{alias-var} changes the value of @var{base-var}.
+@defun defvaralias new-alias base-variable &optional docstring
+This function defines the symbol @var{new-alias} as a variable alias
+for symbol @var{base-variable}. This means that retrieving the value of
+@var{new-alias} returns the value of @var{base-variable}, and changing the
+value of @var{new-alias} changes the value of @var{base-variable}.

 
 If the @var{docstring} argument is non-@code{nil}, it specifies the
 
 If the @var{docstring} argument is non-@code{nil}, it specifies the

-documentation for @var{alias-var}; otherwise, the alias gets the same
-documentation as @var{base-var} has, if any.
+documentation for @var{new-alias}; otherwise, the alias gets the same
+documentation as @var{base-variable} has, if any, unless
+@var{base-variable} is itself an alias, in which case @var{new-alias} gets
+the documentation of the variable at the end of the chain of aliases.
+
+This function returns @var{base-variable}.

 @end defun
 
 @end defun
 

+  Variable aliases are convenient for replacing an old name for a
+variable with a new name.  @code{make-obsolete-variable} declares that
+the old name is obsolete and therefore that it may be removed at some
+stage in the future.
+
+@defun make-obsolete-variable obsolete-name current-name &optional when
+This function makes the byte-compiler warn that the variable
+@var{obsolete-name} is obsolete.  If @var{current-name} is a symbol, it is
+the variable's new name; then the warning message says to use
+@var{current-name} instead of @var{obsolete-name}.  If @var{current-name}
+is a string, this is the message and there is no replacement variable.
+
+If provided, @var{when} should be a string indicating when the
+variable was first made obsolete---for example, a date or a release
+number.
+@end defun
+
+  You can make two variables synonyms and declare one obsolete at the
+same time using the macro @code{define-obsolete-variable-alias}.
+
+@defmac define-obsolete-variable-alias obsolete-name current-name &optional when docstring
+This macro marks the variable @var{obsolete-name} as obsolete and also
+makes it an alias for the variable @var{current-name}.  It is
+equivalent to the following:
+
+@example
+(defvaralias @var{obsolete-name} @var{current-name} @var{docstring})
+(make-obsolete-variable @var{obsolete-name} @var{current-name} @var{when})
+@end example
+@end defmac
+

 @defun indirect-variable variable
 This function returns the variable at the end of the chain of aliases
 of @var{variable}.  If @var{variable} is not a symbol, or if @var{variable} is
 not defined as an alias, the function returns @var{variable}.
 @defun indirect-variable variable
 This function returns the variable at the end of the chain of aliases
 of @var{variable}.  If @var{variable} is not a symbol, or if @var{variable} is
 not defined as an alias, the function returns @var{variable}.

+
+This function signals a @code{cyclic-variable-indirection} error if
+there is a loop in the chain of symbols.

 @end defun
 
 @example
 @end defun
 
 @example


@@ -1692,8 +1904,10 @@ not defined as an alias, the function returns @var{variable}.
 (setq bar 2)
 bar
      @result{} 2
 (setq bar 2)
 bar
      @result{} 2

+@group

 foo
      @result{} 2
 foo
      @result{} 2

+@end group

 (setq foo 0)
 bar
      @result{} 0
 (setq foo 0)
 bar
      @result{} 0


@@ -1701,73 +1915,40 @@ foo
      @result{} 0
 @end example
 
      @result{} 0
 @end example
 

-@node File Local Variables
-@section File Local Variables
-
-  This section describes the functions and variables that affect
-processing of local variables lists in files.
-
-@defopt enable-local-variables
-This variable controls whether to process file local variables lists.  A
-value of @code{t} means process the local variables lists
-unconditionally; @code{nil} means ignore them; anything else means ask
-the user what to do for each file.  The default value is @code{t}.
-@end defopt
-
-@defun hack-local-variables &optional force
-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.
+@node Variables with Restricted Values
+@section Variables with Restricted Values

 
 

-The argument @var{force} usually comes from the argument @var{find-file}
-given to @code{normal-mode}.
-@end defun
+  Ordinary Lisp variables can be assigned any value that is a valid
+Lisp object.  However, certain Lisp variables are not defined in Lisp,
+but in C.  Most of these variables are defined in the C code using
+@code{DEFVAR_LISP}.  Like variables defined in Lisp, these can take on
+any value.  However, some variables are defined using
+@code{DEFVAR_INT} or @code{DEFVAR_BOOL}.  @xref{Defining Lisp
+variables in C,, Writing Emacs Primitives}, in particular the
+description of functions of the type @code{syms_of_@var{filename}},
+for a brief discussion of the C implementation.

 
 

-  If a file local variable list could specify a function that will
-be called later, or an expression that will be executed later, simply
-visiting a file could take over your Emacs.  To prevent this, Emacs
-takes care not to allow local variable lists to set such variables.
-
-  For one thing, any variable whose name ends in @samp{-command},
-@samp{-frame-alist}, @samp{-function}, @samp{-functions},
-@samp{-hook}, @samp{-hooks}, @samp{-form}, @samp{-forms}, @samp{-map},
-@samp{-map-alist}, @samp{-mode-alist}, @samp{-program}, or
-@samp{-predicate} cannot be set in a local variable list.  In general,
-you should use such a name whenever it is appropriate for the
-variable's meaning.  The variables @samp{font-lock-keywords},
-@samp{font-lock-keywords-[0-9]}, and
-@samp{font-lock-syntactic-keywords} cannot be set in a local variable
-list, either.
+  Variables of type @code{DEFVAR_BOOL} can only take on the values
+@code{nil} or @code{t}.  Attempting to assign them any other value
+will set them to @code{t}:

 
 

-  In addition, any variable whose name has a non-@code{nil}
-@code{risky-local-variable} property is also ignored.  So are all
-variables listed in @code{ignored-local-variables}:
+@example
+(let ((display-hourglass 5))
+  display-hourglass)
+     @result{} t
+@end example

 
 

-@defvar ignored-local-variables
-This variable holds a list of variables that should not be
-set by a file's local variables list.  Any value specified
-for one of these variables is ignored.
+@defvar byte-boolean-vars
+This variable holds a list of all variables of type @code{DEFVAR_BOOL}.

 @end defvar
 
 @end defvar
 

-@defun risky-local-variable-p sym
-Returns non-@code{nil} if @var{sym} is risky for any of the reasons
-stated above.
-@end defun
+  Variables of type @code{DEFVAR_INT} can only take on integer values.
+Attempting to assign them any other value will result in an error:

 
 

-  The @samp{Eval:} ``variable'' is also a potential loophole, so Emacs
-normally asks for confirmation before handling it.
-
-@defopt enable-local-eval
-This variable controls processing of @samp{Eval:} in local variables
-lists in files being visited.  A value of @code{t} means process them
-unconditionally; @code{nil} means ignore them; anything else means ask
-the user what to do for each file.  The default value is @code{maybe}.
-@end defopt
-
-  Text properties are also potential loopholes, since their values
-could include functions to call.  So Emacs discards all text
-properties from string values specified in a file's local variables
-list.
+@example
+(setq window-min-height 5.0)
+@error{} Wrong type argument: integerp, 5.0
+@end example

 
 @ignore
    arch-tag: 5ff62c44-2b51-47bb-99d4-fea5aeec5d3e
 
 @ignore
    arch-tag: 5ff62c44-2b51-47bb-99d4-fea5aeec5d3e