@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999
+@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2003
@c Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../info/objects
You can use the same syntax for punctuation characters, but it is
often a good idea to add a @samp{\} so that the Emacs commands for
-editing Lisp code don't get confused. For example, @samp{?\ } is the
-way to write the space character. If the character is @samp{\}, you
-@emph{must} use a second @samp{\} to quote it: @samp{?\\}.
+editing Lisp code don't get confused. For example, @samp{?\(} is the
+way to write the open-paren character. If the character is @samp{\},
+you @emph{must} use a second @samp{\} to quote it: @samp{?\\}.
@cindex whitespace
@cindex bell character
@cindex @samp{\r}
@cindex escape
@cindex @samp{\e}
- You can express the characters Control-g, backspace, tab, newline,
-vertical tab, formfeed, return, del, and escape as @samp{?\a},
+@cindex space
+@cindex @samp{\s}
+ You can express the characters control-g, backspace, tab, newline,
+vertical tab, formfeed, space, return, del, and escape as @samp{?\a},
@samp{?\b}, @samp{?\t}, @samp{?\n}, @samp{?\v}, @samp{?\f},
-@samp{?\r}, @samp{?\d}, and @samp{?\e}, respectively. Thus,
+@samp{?\s}, @samp{?\r}, @samp{?\d}, and @samp{?\e}, respectively.
+Thus,
@example
-?\a @result{} 7 ; @r{@kbd{C-g}}
+?\a @result{} 7 ; @r{control-g, @kbd{C-g}}
?\b @result{} 8 ; @r{backspace, @key{BS}, @kbd{C-h}}
?\t @result{} 9 ; @r{tab, @key{TAB}, @kbd{C-i}}
?\n @result{} 10 ; @r{newline, @kbd{C-j}}
?\f @result{} 12 ; @r{formfeed character, @kbd{C-l}}
?\r @result{} 13 ; @r{carriage return, @key{RET}, @kbd{C-m}}
?\e @result{} 27 ; @r{escape character, @key{ESC}, @kbd{C-[}}
+?\s @result{} 32 ; @r{space character, @key{SPC}}
?\\ @result{} 92 ; @r{backslash character, @kbd{\}}
?\d @result{} 127 ; @r{delete character, @key{DEL}}
@end example
@cindex escape sequence
These sequences which start with backslash are also known as
-@dfn{escape sequences}, because backslash plays the role of an escape
-character; this usage has nothing to do with the character @key{ESC}.
+@dfn{escape sequences}, because backslash plays the role of an
+``escape character''; this terminology has nothing to do with the
+character @key{ESC}. @samp{\s} is meant for use only in character
+constants; in string constants, just write the space.
@cindex control characters
Control characters may be represented using yet another read syntax.
@cindex hyper characters
@cindex super characters
@cindex alt characters
- The X Window System defines three other modifier bits that can be set
+ The X Window System defines three other @anchor{modifier bits}
+modifier bits that can be set
in a character: @dfn{hyper}, @dfn{super} and @dfn{alt}. The syntaxes
for these bits are @samp{\H-}, @samp{\s-} and @samp{\A-}. (Case is
significant in these prefixes.) Thus, @samp{?\H-\M-\A-x} represents
-@kbd{Alt-Hyper-Meta-x}.
+@kbd{Alt-Hyper-Meta-x}. (Note that @samp{\s} with no following @samp{-}
+represents the space character.)
@tex
Numerically, the
bit values are @math{2^{22}} for alt, @math{2^{23}} for super and @math{2^{24}} for hyper.
There is no reason to add a backslash before most characters. However,
you should add a backslash before any of the characters
@samp{()\|;'`"#.,} to avoid confusing the Emacs commands for editing
-Lisp code. Also add a backslash before whitespace characters such as
+Lisp code. You can also add a backslash before whitespace characters such as
space, tab, newline and formfeed. However, it is cleaner to use one of
-the easily readable escape sequences, such as @samp{\t}, instead of an
-actual whitespace character such as a tab.
+the easily readable escape sequences, such as @samp{\t} or @samp{\s},
+instead of an actual whitespace character such as a tab or a space.
+(If you do write backslash followed by a space, you should write
+an extra space after the character constant to separate it from the
+following text.)
@node Symbol Type
@subsection Symbol Type
Here are several examples of symbol names. Note that the @samp{+} in
the fifth example is escaped to prevent it from being read as a number.
-This is not necessary in the sixth example because the rest of the name
+This is not necessary in the seventh example because the rest of the name
makes it invalid as a number.
@example
HCoop / bpt / emacs.git / blobdiff