Is it bad form to call an instance method from within that instance's __init__ method?

Question

I'm building an object that has an attribute whose value is randomly generated at instantiation. The attribute will be assigned a new value (also randomly) from time to time, so I'm defining a method to do so. Is it bad form to initialize the attribute by calling that method from within __init__? It would be easy enough to avoid—I'd just have to duplicate a small amount of code—but it seems more elegant to call the method. Here's an example:

import random

class Robot(object):
    def __init__(self):
        self.setDirection()

    def setDirection(self):
        self.direction = random.random() * 360

Answer 1

It's fine to call instance methods within __init__, but be careful if they might be overridden in subclasses:

class A(object):

    def __init__(self):
        self.greet()

    def greet(self):
        print('Hello from A')


class B(A):

    def __init__(self, name):
        super(B, self).__init__()
        self.name = name

    def greet(self):
        print('Hello from B', self.name)

Now if B is instantiated, B.greet is called by A.__init__ before its preconditions are satisfied (self.name is not defined).

Answer 2

There's nothing wrong with calling other instance methods within __init__.

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Note that in python there is a distinction between instance methods and class methods. I can't think of a good reason to use a class method within __init__ -- which isn't to say that a good reason doesn't exist, but that the cases are probably pretty rare.