Mercurial > hg-stable
changeset 13026:53391819f195
check-code: catch Python 'is' comparing number or string literals
The Python 'is' operator compares object identity, so it should
definitely not be applied to string or number literals, which Python
implementations are free to represent with a temporary object.
This should catch the following kinds of bogus expressions (examples):
x is 'foo' x is not 'foo'
x is "bar" x is not "bar"
x is 42 x is not 42
x is -36 x is not -36
As originally proposed by Martin Geisler, amended with catching
negative numbers.
| author | Adrian Buehlmann <adrian@cadifra.com> |
|---|---|
| date | Sun, 21 Nov 2010 11:52:27 +0100 |
| parents | da69a1597285 |
| children | 7f2ecb64140d |
| files | contrib/check-code.py tests/test-check-code.t |
| diffstat | 2 files changed, 42 insertions(+), 0 deletions(-) [+] |
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--- a/contrib/check-code.py Sun Nov 21 13:16:59 2010 +0100 +++ b/contrib/check-code.py Sun Nov 21 11:52:27 2010 +0100 @@ -149,6 +149,7 @@ (r'raise Exception', "don't raise generic exceptions"), (r'ui\.(status|progress|write|note|warn)\([\'\"]x', "warning: unwrapped ui message"), + (r' is\s+(not\s+)?["\'0-9-]', "object comparison with literal"), ] pyfilters = [
--- a/tests/test-check-code.t Sun Nov 21 13:16:59 2010 +0100 +++ b/tests/test-check-code.t Sun Nov 21 11:52:27 2010 +0100 @@ -52,3 +52,44 @@ > y = format(x) any/all/format not available in Python 2.4 [1] + + $ cat > is-op.py <<EOF + > # is-operator comparing number or string literal + > x = None + > y = x is 'foo' + > y = x is "foo" + > y = x is 5346 + > y = x is -6 + > y = x is not 'foo' + > y = x is not "foo" + > y = x is not 5346 + > y = x is not -6 + > EOF + + $ "$check_code" ./is-op.py + ./is-op.py:3: + > y = x is 'foo' + object comparison with literal + ./is-op.py:4: + > y = x is "foo" + object comparison with literal + ./is-op.py:5: + > y = x is 5346 + object comparison with literal + ./is-op.py:6: + > y = x is -6 + object comparison with literal + ./is-op.py:7: + > y = x is not 'foo' + object comparison with literal + ./is-op.py:8: + > y = x is not "foo" + object comparison with literal + ./is-op.py:9: + > y = x is not 5346 + object comparison with literal + ./is-op.py:10: + > y = x is not -6 + object comparison with literal + [1] +