[docs] [issue13667] __contains__ method behavior  João Bernardo
report at bugs.python.org Wed Dec 28 10:11:10 CET 2011  New
submission from João Bernardo <jbvsmo at gmail.com>:  Hi, I'm
working on a class which implements the __contains__ method but
the way I would like it to work is by generating an object that
will be evaluated later.  It'll return a custom object instead
of True/False  class C:     def __contains__(self, x):
return "I will evaluate this thing later... Don't bother now"
but when I do:  >>> 1 in C()  It seems to evaluate the answer
with bool!  Reading the docs (http://docs.python.org/py3k/refere
nce/expressions.html#membership-test-details) It says:  "`x in
y` is true if and only if `y.__contains__(x)` is true."  It
looks like the docs doesn't match the code and the code is
trying to mimic the behavior of lists/tuples where "x in y" is
the same as   and always yield True or False.  There is a reason
why it is that way?   assignee: docs at python components:
Documentation, Interpreter