Backspace escape in regular expression¶
ID: py/regex/backspace-escape Kind: problem Severity: recommendation Precision: very-high Tags: - maintainability Query suites: - python-security-and-quality.qls
The meaning of the
\b escape sequence inside a regular expression depends on its syntactic context: inside a character class, it matches the backspace character; outside of a character class, it matches a word boundary. This context dependency makes regular expressions hard to read, so the
\b escape sequence should not be used inside character classes.
\b in character classes with the semantically identical escape sequence
In the following example, the regular expression contains two uses of
\b: in the first case, it matches a word boundary, in the second case it matches a backspace character.
import re matcher = re.compile(r"\b[\t\b]") def match_data(data): return bool(matcher.match(data))
You can make the regular expression easier for other developers to interpret, by rewriting it as
Python Standard Library: Regular expression operations.