From e8239b8e8199b76ef647ff3bf080ce2eb7733e04 Mon Sep 17 00:00:00 2001 From: Pablo Galindo Date: Sun, 20 Jan 2019 18:57:56 +0000 Subject: [PATCH] Add information about DeprecationWarning for invalid escaped characters in the re module (GH-5255) --- Doc/library/re.rst | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/Doc/library/re.rst b/Doc/library/re.rst index 2f829559ff1..ac6455a2207 100644 --- a/Doc/library/re.rst +++ b/Doc/library/re.rst @@ -28,7 +28,10 @@ character for the same purpose in string literals; for example, to match a literal backslash, one might have to write ``'\\\\'`` as the pattern string, because the regular expression must be ``\\``, and each backslash must be expressed as ``\\`` inside a regular Python string -literal. +literal. Also, please note that any invalid escape sequences in Python's +usage of the backslash in string literals now generate a :exc:`DeprecationWarning` +and in the future this will become a :exc:`SyntaxError`. This behaviour +will happen even if it is a valid escape sequence for a regular expression. The solution is to use Python's raw string notation for regular expression patterns; backslashes are not handled in any special way in a string literal