On 08/09/2017 07:54 AM, Steve D'Aprano wrote:
On Wed, 9 Aug 2017 10:08 am, Ian Pilcher wrote:
I have created a class to provide a "hash consing"[1] set.
Your footnote for [1] appears to be missing. What's a hash consing set? It
appears to be nothing more than frozen sets which you put in a cache so as to
confuse identity and value *wink*
Uugh. Here's the link:
https://en.wikipedia.org/wiki/Hash_consing
I doubt very much you're actually saving any time, since you create a temporary
frozen set before returning the one in the cache. You might save some memory
though.
Indeed. This is all about using memory efficiently.
Your __init__ method does nothing. Get rid of it and save two lines of code :-)
Well, it prevents frozenset.__init__ from being called.
Also, there is at least theoretically the vague possibility that
frozenset.__init__ does something (phones home to Guido?) so you shouldn't
block it if you don't need to.
I do want to prevent frozenset.__init__ from being called *again* when
an existing instance is returned, so I've decided to take this
approach:
def __new__(cls, *args, **kwargs):
self = super(UniqueSet, cls).__new__(cls, *args, **kwargs)
self._initialized = False
return UniqueSet._registry.setdefault(self, self)
def __init__(self, *args, **kwargs):
if not self._initialized:
super(UniqueSet, self).__init__(self, *args, **kwargs)
self._initialized = True
--
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Ian Pilcher arequip...@gmail.com
-------- "I grew up before Mark Zuckerberg invented friendship" --------
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