Path: csiph.com!eternal-september.org!feeder.eternal-september.org!nntp.eternal-september.org!.POSTED!not-for-mail
From: Veek M <veekjunk@foobar.com>
Newsgroups: comp.lang.python
Subject: Python __hash__ return value - what use is it?
Date: Sun, 31 May 2026 08:28:46 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 45
Message-ID: <10vgrfu$1dchl$1@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Injection-Date: Sun, 31 May 2026 08:28:47 +0000 (UTC)
Injection-Info: dont-email.me; logging-data="1487413"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1+OdI3NLe8RTV6DUKibHZZl"; posting-host="19ee0fa4a702ab58bc30ce99d61c320d"
User-Agent: Pan/0.154 (Izium; 517acf4)
Cancel-Lock: sha1:dyQzp2u3BVVf388vizXNLCI8aCs= sha256:Rmf3W68c43YI9vk0tP58jtqoGwHI3CtpBnh2rn/R1VQ= sha1:hmCXF4xCjCXJsCQAOgLC2icIblw=
Xref: csiph.com comp.lang.python:197793

1. So I am returning 1 for every instance of MyClass and then inserting 
the instances into a set. However when I print the set I see individual 
instances though I want the instances to be the treated the same .ie there 
should be just one instance in the set because the return value from 
__hash__ is always 1.

In the dictionary when I print it I see the instances as individual keys 
though I want to see a single key - what gives?? Why is the return value 
of __hash__ being ignored?? (I can see it's being called)

2. When is __eq__ used? If I have two instances and want to make them 
equal - what's the use case?

#!/usr/bin/python

class MyClass:
    def __bool__(self):
        print('in __bool__')
        return True

    def __hash__(self):
        # hash value is not a key
        print('in __hash__')
        return 1

    def __eq__(self, val):
        print('in __eq__', val)
        return True

c = MyClass()
d = MyClass()

if c:
    print("true")

print('-----')
s = set()
s.add(c)
s.add(d)
print(s)

print('-----')
d = { c : "10", d : "20"  }
print(d)