Question

So I need to mutate a method at object initialization based upon input to __init__ (for those interested, I’m changing the navigate_to method in a test framework based upon which type of automator is being instantiated (Selenium, mobile device automator, etc)). I’ve come up with a solution using a conditionally created closure in __init__, but it seems like there should be a more elegant and optimized way to do this. As an example of the approach:

class Foo(object):
    def __init__(self, x):
        self.x = x
        if x % 2:
            def odd_or_even():
                return '%d odd' % self.x
        else:
            def odd_or_even():
                return '%d even' % self.x
        self.odd_or_even = odd_or_even

Resulting in:

>>> foo1 = Foo(1)
>>> foo2 = Foo(2)
>>> foo1.odd_or_even()
'1 odd'
>>> foo2.odd_or_even()
'2 even'

This works, but I feel like there should be some better way to do this. Suggestions?

Answer 1

I would make a different method for each type of automator, and then a generic method that uses the state of self to determine which of the specific methods to call.

Why do you need to create a closure containing the decision, when you can just record the decision in self?