From 2aed279be18ddd1e2c2b6a8102b94127fe41906c Mon Sep 17 00:00:00 2001 From: Eli Zaretskii Date: Sat, 22 Feb 2020 11:07:42 +0200 Subject: [PATCH] Warn about the likes of "[:alnum:]" in regexps * doc/lispref/searching.texi (Char Classes): Warn about erroneous usage of named character classes. Suggested by Stephen Leake . --- doc/lispref/searching.texi | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/doc/lispref/searching.texi b/doc/lispref/searching.texi index 1f6db0643e8..a4d5a27203f 100644 --- a/doc/lispref/searching.texi +++ b/doc/lispref/searching.texi @@ -582,8 +582,13 @@ an unquoted @samp{[} is special again and a @samp{]} not. @cindex alpha character class, regexp @cindex xdigit character class, regexp - Here is a table of the classes you can use in a character alternative, -and what they mean: + Below is a table of the classes you can use in a character +alternative, and what they mean. Note that the @samp{[} and @samp{]} +characters that enclose the class name are part of the name, so a +regular expression using these classes needs one more pair of +brackets. For example, a regular expression matching a sequence of +one or more letters and digits would be @samp{[[:alnum:]]+}, not +@samp{[:alnum:]+}. @table @samp @item [:ascii:] -- 2.39.2