[issue13667] __contains__ method behavior

Changes by Benjamin Peterson : -- resolution: -> rejected status: open -> closed ___ Python tracker ___ ___ Python-bugs-list mailing

[issue13667] __contains__ method behavior

João Bernardo added the comment: The problem with `not in` is because it must evaluate the result. It's not just another operator like "==" and "!=". Looks like we're suffering from premature optimization and now it would break a lot of code to make it good. For my application, I created a d

[issue13667] __contains__ method behavior

Alex Gaynor added the comment: For what it's worth I proposed this on -ideas a while ago, the sticking points were what does `not in` do (no one had an answer anyone was happy with for this), and do we need a way to override it from the other perspective (e.g. if I want to do `SpecialObj() in

[issue13667] __contains__ method behavior

Raymond Hettinger added the comment: -1 on this proposal. It has everyone paying a price for a questionable feature that would benefit very few. -- nosy: +rhettinger ___ Python tracker __

[issue13667] __contains__ method behavior

Georg Brandl added the comment: It's defined that way because it's a slot returning a bool, so it doesn't need to return anything except for 0 or 1. Changing this to return a PyObject would mean that every extension module (i.e. module written in C) that defines a custom __contains__ would ne

[issue13667] __contains__ method behavior

João Bernardo added the comment: Using my poor grep abilities I found that on Objects/typeobject.c (I replaced some declarations/error checking from the code with ...) static int slot_sq_contains(PyObject *self, PyObject *value) { ... func = lookup_maybe(self, "__contains__", &contains_

[issue13667] __contains__ method behavior

Benjamin Peterson added the comment: 2011/12/28 João Bernardo : > > João Bernardo added the comment: > > I see that every other comparison operator (<, >, <=, >=, ==, !=) except for > `is` work the way I expect and is able to return anything. > > e.g. > numpy.arange(5) < 3 > array([ True,

[issue13667] __contains__ method behavior

João Bernardo added the comment: I see that every other comparison operator (<, >, <=, >=, ==, !=) except for `is` work the way I expect and is able to return anything. e.g. >>> numpy.arange(5) < 3 array([ True, True, True, False, False], dtype=bool) I didn't checked the code (and probably

[issue13667] __contains__ method behavior

Benjamin Peterson added the comment: I think the idea has some merit. I think it should be well vetted on python-ideas, though. One thing that will certianly weigh against it is that implementation would not be trivial. -- ___ Python tracker

[issue13667] __contains__ method behavior

Georg Brandl added the comment: Well, usually what you want *is* a boolean indicating whether the element is in the collection or not. Being able to overload "in", mostly for metaprogramming purposes, is a request that probably nobody thought of when implementing "in". -- nosy: +benj

[issue13667] __contains__ method behavior

Changes by João Bernardo : -- type: behavior -> enhancement ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe: htt

[issue13667] __contains__ method behavior

João Bernardo added the comment: @Georg Brandl Oh sorry, now I see... true != True But still, why is that the default behavior? Shouldn't it use whatever the method returns? -- type: enhancement -> behavior versions: +Python 3.2 ___ Python tracker

[issue13667] __contains__ method behavior

Georg Brandl added the comment: "an object is true" is a short way of saying "bool(obj) is True". So the docs match the behavior. Returning the actual object instead of True/False from the "in" operator is a feature request. -- assignee: docs@python -> nosy: +georg.brandl type: beh

[issue13667] __contains__ method behavior

New submission from João Bernardo : 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):