Guido van Rossum wrote:
On Tue, Jul 27, 2010 at 3:29 PM, Mathias Panzenböck
So it doesn't help that 'in' may return something else than a bool because the method is called on the wrong object for your purposes.
Well that pretty much kills the proposal. I can't believe nobody (including myself) figured this out earlier in the thread. :-(
Alternatively, it could be taken as a sign that there is a special method missing -- there should be an __in__ method that is tried on the first operand before trying __contains__ on the second. (And if we'd thought of this at the beginning, __contains__ would have been called __rin__. :-)