Python Language Classes Monkey Patching
Example
In this case, "monkey patching" means adding a new variable or method to a class after it's been defined. For instance, say we defined class A as
class A(object):
def __init__(self, num):
self.num = num
def __add__(self, other):
return A(self.num + other.num)
But now we want to add another function later in the code. Suppose this function is as follows.
def get_num(self):
return self.num
But how do we add this as a method in A? That's simple we just essentially place that function into A with an assignment statement.
A.get_num = get_num
Why does this work? Because functions are objects just like any other object, and methods are functions that belong to the class.
The function get_num shall be available to all existing (already created) as well to the new instances of A
These additions are available on all instances of that class (or its subclasses) automatically. For example:
foo = A(42)
A.get_num = get_num
bar = A(6);
foo.get_num() # 42
bar.get_num() # 6
Note that, unlike some other languages, this technique does not work for certain built-in types, and it is not considered good style.
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