Message287267
| Author |
Eric Lafontaine |
| Recipients |
Eric Lafontaine, christian.heimes, docs@python, ezio.melotti, mark.dickinson, nparikh, r.david.murray, vstinner |
| Date |
2017年02月08日.01:25:03 |
| SpamBayes Score |
-1.0 |
| Marked as misclassified |
Yes |
| Message-id |
<1486517105.06.0.812064615771.issue16011@psf.upfronthosting.co.za> |
| In-reply-to |
| Content |
Hi all,
Here are the test I've made to understand the behavior :
class Foo_42(object):
def __contains__(self,item): return 42
class Foo_neg(object):
def __contains__(self,item): return -42
class Foo_None(object):
def __contains__(self,item): return
class Foo_false(object):
def __contains__(self,item): return False
class Foo_true(object):
def __contains__(self,item): return True
for foo in [Foo_false(),Foo_None(),Foo_neg(),Foo_true(),Foo_42()]:
print("3 in foo:" + str(3 in foo))
print("foo.__contains__(3)" + str(foo.__contains__(3)))
which output this :
3 in foo:False
foo.__contains__(3)False
3 in foo:False
foo.__contains__(3)None
3 in foo:True
foo.__contains__(3)-42
3 in foo:True
foo.__contains__(3)True
3 in foo:True
foo.__contains__(3)42
So as long as __contains__ return False or None, the 'in' operator will be False. Otherwise true. |
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