According to my understanding, sets can only have one of each object in them. But I have found the following example where a set has two of the same object
class myObject:
def __init__(self, x):
self.x = x
def set(self, x):
self.x = x
def __hash__(self):
return self.x
def __eq__(self, o):
return self.x == o.x
def __str__(self):
return str(self.x)
def __repr__(self):
return str(self.x)
When I run the following:
x = myObject(1)
mySet = {x}
x.set(2)
mySet.add(x)
print(mySet)
x.set(3)
print(mySet)
I get the following output:
{2, 2}
{3, 3}
If I remove the __str__ and __repr__ methods it shows there are two objects in the set with the same memory address:
{<__main__.myObject object at 0x10e3a10d0>, <__main__.myObject object at 0x10e3a10d0>}
I am aware python doesn't allow things like lists to be hashed because the hashcode can change causing a similar error to what is shown above. Why is python allowing this but not for things like lists etc. Surely Python should also have some way of managing changing hashes.
I have tested this same example on java and the same thing happens. Why do these languages allow this?
