Finding x is 1, and x is 'foo' comparisons in a code base

Thomas Heller theller at
Tue Jan 17 13:47:53 EST 2012

Am 17.01.2012 18:10, schrieb Alex Willmer:
> Hello,
> I'm looking for a way to find the occurrences of x is y comparisons in
> an existing code base. Except for a few special cases (e.g. x is [not]
> None) they're a usually mistakes, the correct test being x == y.
> However they happen to work most of the time on CPython (e.g. when y
> is a small integer or string) so they slip into production code
> unnoticed.
> PyLint and PyFlakes don't check this AFAICT. Any suggestions for such
> a tool, or a pointer how to add the check to an existing tool would be
> most welcome.

Pychecker contains a check for this mistake.

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