http://bidict.rtfd.io>.
Feedback always welcome.
Thanks,
Josh
-- Forwarded message --
From: Raymond Hettinger
Date: Mon, Nov 20, 2017 at 4:46 PM
Subject: Re: __hash__ and ordered vs. unordered collections
To: j...@math.brown.edu
If you want to make ordered and unordered coll
On Tue, Nov 21, 2017 at 6:50 AM, Josh B. wrote:
> On Monday, November 20, 2017 at 1:55:26 PM UTC-5, Chris Angelico wrote:
>> But what you have is the strangeness of non-transitive equality, which
>> is likely to cause problems.
>
> But this is exactly how Python's built-in dict and OrderedDict beh
On Monday, November 20, 2017 at 2:31:40 PM UTC-5, MRAB wrote:
> What if there are duplicate elements?
>
> Should that be MyColl(some_elements) == MyOrderedColl(other_elements)
> iff len(some_elements) == len(other_elements) and set(some_elements) ==
> set(other_elements)?
Yes, that's what I mea
On Monday, November 20, 2017 at 1:55:26 PM UTC-5, Chris Angelico wrote:
> But what you have is the strangeness of non-transitive equality, which
> is likely to cause problems.
But this is exactly how Python's built-in dict and OrderedDict behave:
>>> od = OrderedDict([(1, 0), (2, 0), (3, 0)])
>>>
On 2017-11-20 17:47, Josh B. wrote:
Suppose we're implementing an immutable collection type that comes in unordered
and ordered flavors. Let's call them MyColl and MyOrderedColl.
We implement __eq__ such that MyColl(some_elements) ==
MyOrderedColl(other_elements) iff set(some_elements) == set(
On Tue, Nov 21, 2017 at 4:47 AM, Josh B. wrote:
> Now for the question: Is this useful? I ask because this leads to the
> following behavior:
>
unordered = MyColl([1, 2, 3])
ordered = MyOrderedColl([3, 2, 1])
s = {ordered, unordered}
len(s)
> 1
s = {ordered}
unordere
Suppose we're implementing an immutable collection type that comes in unordered
and ordered flavors. Let's call them MyColl and MyOrderedColl.
We implement __eq__ such that MyColl(some_elements) ==
MyOrderedColl(other_elements) iff set(some_elements) == set(other_elements).
But MyOrderedColl(so
