@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2002, 2003,
-@c 2004, 2005 Free Software Foundation, Inc.
+@c 2004, 2005, 2006 Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../info/commands
@node Command Loop, Keymaps, Minibuffers, Top
arguments. This leads quickly to an error if the command requires one
or more arguments.
-@item
-It may be a Lisp expression that is not a string; then it should be a
-form that is evaluated to get a list of arguments to pass to the
-command.
-@cindex argument evaluation form
-
-If this expression reads keyboard input (this includes using the
-minibuffer), keep in mind that the integer value of point or the mark
-before reading input may be incorrect after reading input. This is
-because the current buffer may be receiving subprocess output;
-if subprocess output arrives while the command is waiting for input,
-it could relocate point and the mark.
-
-Here's an example of what @emph{not} to do:
-
-@smallexample
-(interactive
- (list (region-beginning) (region-end)
- (read-string "Foo: " nil 'my-history)))
-@end smallexample
-
-@noindent
-Here's how to avoid the problem, by examining point and the mark only
-after reading the keyboard input:
-
-@smallexample
-(interactive
- (let ((string (read-string "Foo: " nil 'my-history)))
- (list (region-beginning) (region-end) string)))
-@end smallexample
-
@item
@cindex argument prompt
It may be a string; then its contents should consist of a code character
Actual reading of arguments is controlled by the rest of the prompt
string (starting with the first character that is not @samp{*} or
@samp{@@}).
+
+@item
+It may be a Lisp expression that is not a string; then it should be a
+form that is evaluated to get a list of arguments to pass to the
+command. Usually this form will call various functions to read input
+from the user, most often through the minibuffer (@pxref{Minibuffers})
+or directly from the keyboard (@pxref{Reading Input}).
+@cindex argument evaluation form
+
+Providing point or the mark as an argument value is also common, but
+if you do this @emph{and} read input (whether using the minibuffer or
+not), be sure to get the integer values of point or the mark after
+reading. The current buffer may be receiving subprocess output; if
+subprocess output arrives while the command is waiting for input, it
+could relocate point and the mark.
+
+Here's an example of what @emph{not} to do:
+
+@smallexample
+(interactive
+ (list (region-beginning) (region-end)
+ (read-string "Foo: " nil 'my-history)))
+@end smallexample
+
+@noindent
+Here's how to avoid the problem, by examining point and the mark after
+reading the keyboard input:
+
+@smallexample
+(interactive
+ (let ((string (read-string "Foo: " nil 'my-history)))
+ (list (region-beginning) (region-end) string)))
+@end smallexample
@end itemize
@cindex examining the @code{interactive} form
commands.
Normally, commands specify which representation to use for the prefix
-argument, either numeric or raw, in the @code{interactive} declaration.
+argument, either numeric or raw, in the @code{interactive} specification.
(@xref{Using Interactive}.) Alternatively, functions may look at the
value of the prefix argument directly in the variable
@code{current-prefix-arg}, but this is less clean.