Binding a method to class instance on fly in Python

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class mc:
    def show(self):
        self.func()


a = mc()
def myfunc(self):
    print('instance function')
a.func = myfunc
a.show()

The above does not work: TypeError: myfunc() missing 1 required positional argument: 'self'.

Why is the instance name not automatically inserted by Python, considering that I'm using dot notation?

instance methods function class python
2 Answers

It can work like this, since the function isn't really an instance method

class mc:
    def show(self):
         self.x = 1
         func(self)


a = mc()
def myfunc(self):
    print (self.x)
    print('instance function')
a.func = myfunc
a.show()
user_8714100

You can dynamically add a method to a class using monkey patching.

class mc:
    def show(self):
        self.func()

a = mc()
def myfunc(self):
    print('instance function')
mc.func = myfunc
a.show()
user_177698150
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