From 8284c4a7fb27efd55323513572e247a895a35ae1 Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Wed, 6 Feb 2008 20:47:09 +0000 Subject: [PATCH] Fix-up the _from_iterable() method to return instances of the subclass where it is used. In its previous form, it always returned instance of frozenset which makes this ABC nearly useless as a mixin. In its new form, it needs to be able to assume that the constructor will take a frozenset input. This will usually be true. If it is not, then only one method (this one) will need to be overriden by the subclass to let it know about the unique constructor signature. Will add info on this to the docs. --- Lib/_abcoll.py | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/Lib/_abcoll.py b/Lib/_abcoll.py index 90a78cb3bbe..030bd7a97e0 100644 --- a/Lib/_abcoll.py +++ b/Lib/_abcoll.py @@ -204,7 +204,12 @@ class Set(metaclass=ABCMeta): @classmethod def _from_iterable(cls, it): - return frozenset(it) + '''Construct an instance of the class from any iterable input. + + Must override this method if the class constructor signature + will not accept a frozenset for an input. + ''' + return cls(frozenset(it)) def __and__(self, other): if not isinstance(other, Iterable):