python / python/cpython

Inconsistent behaviors of `dict.keys()`, `dict.values()` and `dict.items()` with `==`

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docs type-bug
Dominant language
Python
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Description

Bug report

Bug description:

dict.keys() and dict.keys() are True because they're the same type and dict.keys() and a list or tuple are False because they're different types but dict.keys() and a set or frozenset are True even though their types are different and it seems like the elements in dict.keys() are ordered but not unordered as shown below:

v = {'A':'B', 'C':'D', 'E':'F', 'G':'H', 'I':'J'}.keys()

print(v)
# dict_keys(['A', 'C', 'E', 'G', 'I'])

print(v == {'A':'B', 'C':'D', 'E':'F', 'G':'H', 'I':'J'}.keys())
# True

print(v == ['A', 'C', 'E', 'G', 'I'])            # list
print(v == ('A', 'C', 'E', 'G', 'I'))            # tuple
# False

print(v == {'A', 'C', 'E', 'G', 'I'})            # set
print(v == frozenset(['A', 'C', 'E', 'G', 'I'])) # frozenset
# True

for x in v:
    print(x)
# A
# C
# E
# G
# I

And, dict.items() and dict.items() are True because they're the same type and dict.items() and a list or tuple are False because they're different types but dict.items() and a set or frozenset are True even though their types are different and it seems like the elements in dict.items() are ordered but not unordered as shown below:

v = {'A':'B', 'C':'D', 'E':'F', 'G':'H', 'I':'J'}.items()

print(v)
# dict_items([('A', 'B'), ('C', 'D'), ('E', 'F'), ('G', 'H'), ('I', 'J')])

print(v == {'A':'B', 'C':'D', 'E':'F', 'G':'H', 'I':'J'}.items())
# True

print(v == [('A', 'B'), ('C', 'D'), ('E', 'F'), ('G', 'H'), ('I', 'J')])            # list
print(v == (('A', 'B'), ('C', 'D'), ('E', 'F'), ('G', 'H'), ('I', 'J')))            # tuple
# False

print(v == {('A', 'B'), ('C', 'D'), ('E', 'F'), ('G', 'H'), ('I', 'J')})            # set
print(v == frozenset([('A', 'B'), ('C', 'D'), ('E', 'F'), ('G', 'H'), ('I', 'J')])) # frozenset
# True

for x in v:
    print(x)
# ('A', 'B')
# ('C', 'D')
# ('E', 'F')
# ('G', 'H')
# ('I', 'J')

Finally, dict.values() and dict.values(), a list, tuple, set or frozenset are all False whether their types are the same or different and whether their elements are ordered or unordered as shown below:

v = {'A':'B', 'C':'D', 'E':'F', 'G':'H', 'I':'J'}.values()

print(v)
# dict_values(['B', 'D', 'F', 'H', 'J'])

print(v == {'A':'B', 'C':'D', 'E':'F', 'G':'H', 'I':'J'}.values()) # dict.values()    
print(v == ['B', 'D', 'F', 'H', 'J'])                              # list
print(v == ('B', 'D', 'F', 'H', 'J'))                              # tuple
print(v == {'B', 'D', 'F', 'H', 'J'})                              # set
print(v == frozenset(['B', 'D', 'F', 'H', 'J']))                   # frozenset
# False

for x in v:
    print(x)
# B
# D
# F
# H
# J
CPython versions tested on:

3.12

Operating systems tested on:

No response

Linked PRs
  • gh-155858

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

The report names dict.keys(), dict.values(), and dict.items() and provides executable equality examples; start by running them on CPython 3.12. Compare the documented and implemented equality behavior, then use linked PR gh-155858 as the current work reference; done requires an agreed behavior and matching tests.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
backend
Issue type
Bug
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
20/100

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