Create method with class self variables outside of a python class and then add it as a method to class

Question

I would like to create a method outside a class that works with some self class variables, and then add it to the class when is instanciated.

Something like this:

used_method = int(input())

if used_method == 1:
    def outside_method(var1=self.var1, var2=self.var2):
      return (var1 + var2)
elif used_method == 2:
    def outside_method(var1=self.var1, var2=self.var2, var3=self.varx):
      return (var1 - var2) * var3

class myClass():
    def __init__(self, varx=3, vary=2):
        self.varx = varx
        self.vary = vary
        self.var1 = 0
        self.var2 = 0
    
    def _method1(self, x, y):
        a = x + y
        b = x * y
        return a, b
    
    def run(self)
        self.var1, self.var2 = self._method1(self.varx, self.vary)
        target = outside_method()
        print(target)

So, when:

used_method = 1
myobject = myClass()
myobject.run()

Output should be 11, but when:

used_method = 2
myobject = myClass()
myobject.run()

Output should be -3.

This is because the class is very big and I want to allow the user to customize the outside_method that works with self variables that change on each iteration of the run method.

Can somebody help me with this please?

Thanks in advance.

Answer 1

Example 1:

used_method = int(input())

if used_method == 1:
    def outside_method(self):
        return self.var1 + self.var2
elif used_method == 2:
    def outside_method(self):
        return (self.var1 - self.var2) * self.varx


class myClass():
    def __init__(self, varx=3, vary=2):
        self.varx = varx
        self.vary = vary
        self.var1 = 0
        self.var2 = 0

    def _method1(self, x, y):
        a = x + y
        b = x * y
        return a, b

    def run(self):
        self.var1, self.var2 = self._method1(self.varx, self.vary)
        target = outside_method(self)
        print(target)

Example 2:

used_method = int(input())

if used_method == 1:
    def outside_method(var1, var2):
        return var1 + var2
elif used_method == 2:
    def outside_method(var1, var2, var3):
        return (var1 - var2) * var3


class myClass():
    def __init__(self, varx=3, vary=2):
        self.varx = varx
        self.vary = vary
        self.var1 = 0
        self.var2 = 0

    def _method1(self, x, y):
        a = x + y
        b = x * y
        return a, b

    def run(self):
        self.var1, self.var2 = self._method1(self.varx, self.vary)
        args = [self.var1, self.var2]
        target = outside_method(*((*args, self.varx) if used_method == 2 else args))
        print(target)