Add __eq__ and __ne__ to collections.abc.Sequence.

[NeilGirdhar]

BPO	27802
Nosy	@bitdancer, @vadmium, @NeilGirdhar
Files	abc_eq.diff

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2016-08-19.18:31:18.103>
created_at = <Date 2016-08-19.12:42:24.855>
labels = ['type-feature', 'library']
title = 'Add __eq__ and __ne__ to collections.abc.Sequence.'
updated_at = <Date 2016-08-19.18:31:18.102>
user = 'https://github.com/NeilGirdhar'

bugs.python.org fields:

activity = <Date 2016-08-19.18:31:18.102>
actor = 'gvanrossum'
assignee = 'none'
closed = True
closed_date = <Date 2016-08-19.18:31:18.103>
closer = 'gvanrossum'
components = ['Library (Lib)']
creation = <Date 2016-08-19.12:42:24.855>
creator = 'NeilGirdhar'
dependencies = []
files = ['44151']
hgrepos = []
issue_num = 27802
keywords = ['patch']
message_count = 5.0
messages = ['273114', '273119', '273121', '273122', '273135']
nosy_count = 3.0
nosy_names = ['r.david.murray', 'martin.panter', 'NeilGirdhar']
pr_nums = []
priority = 'normal'
resolution = 'rejected'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue27802'
versions = ['Python 3.6']

[NeilGirdhar]

Both Mapping and Set provide __eq__ and __ne__. Why not have Sequence do the same?

[vadmium]

Your implementation looks like it will make a Sequence equal to a list and a tuple, even though lists and tuples are never equal to each other.

[NeilGirdhar]

That's a really good point. Perhaps bring it up on ideas so that it can be discussed by more people? I don't know what the answer is.

[NeilGirdhar]

(there's already an open thread.)

[bitdancer]

I was wondering the same thing recently, thanks for opening this issue.

Here is my use case: I'm implementing a PersistentList, and I want it to be equal to a 'real' list, but not equal to a tuple. Frankly, I hadn't thought about the latter problem before this issue, so my __eq__ code in my concrete class is currently broken. I'll need to explicitly check for list subclasses and PersistentList subclasses. I'm not sure there's any way to "generalize" that. I presume that's why Sequence doesn't have the methods.

The answer would seem to be to have explicit 'List' and 'Tuple' abcs.