Method vs function-valued field in Python

user_6454908 0
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I am switching from MATLAB to Python and numpy and I would like to know if there is any difference between the option to define a class method and the option to the function to a class field (instance variable)? Here is the example:

class MyClass:
    def __init__(self, a):            
        self.a=a    #some variable

    def add(self,b):
        return self.a+b

vs

class MyClass:
    def __init__(self, a):
        self.a=a    #some variable            
        self.add = lambda b: self.a+b

It works in both cases when I call 

my_object=MyClass(2)
print(my_object.add(2)) #prints 4

Are there any differences between these two approaches? Any best practices/downsides? To me, the first one feels more "proper OOP", but the second one feels more flexible. Or, maybe, the definitions are identical, because of the way Python works under the hood?

methods python
1 Answers

The second one can't be overridden and takes a lot more space, because there's a separate function in every instance's __dict__ instead of one function in the class __dict__. (Instance method objects are created and reclaimed on the fly if you do it the normal way, or optimized out entirely in many cases depending on Python version.)

user_23571120
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