In Python, if I have the following code:
r = Numeric(str)
i = int(r)
if r == i :
return i
return r
Is this equivalent to:
r = Numeric(str)
return r
Or do the == values of different types r and i give different return values r and i?
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3 Answers
It all depends if the class implements an adequate __eq__ method to override == operator.
Edit: Added a little example:
>>> class foo:
... def __init__(self,x):
... self.x = x
... def __eq__(self,y):
... return int(self.x)==int(y)
...
>>> f = foo(5)
>>> f == '5'
True
>>> 5 == '5'
False
Comments
Lets see:
>>> float(2) == int(2)
True
Different types can be considered equal using ==.
Comments
Question: "do the == values of different types r and i give different return values r and i?"
Answer: clearly they are different; they have different types.
>>> print(type(i))
<type 'int'>
>>> print(type(n))
<class '__main__.Numeric'>
In the above example, I declared a class called Numeric to have something to test. If you actually have a module that implements a class called Numeric, it won't say __main__.Numeric but something else.
If the class implements a __eq__() method function, then the results of == will depend on what that function does.
class AlwaysEqual(object):
def __init__(self, x):
self.x = x
def __eq__(self, other):
return True
With the above, we can now do:
>>> x = AlwaysEqual(42)
>>> print(x == 6*9)
True
>>> print(x == "The answer to life, the universe, and everything")
True
