is there any way to prevent side effects in python?

Question

Is there any way to prevent side effects in python? For example, the following function has a side effect, is there any keyword or any other way to have the python complain abou

Answer 1

You'll have to make a copy of the list first. Something like this:

def func_without_side_affect(a):
    b = a[:]
    b.append('foo')
    return b

This shorter version might work for you too:

def func_without_side_affect(a):
    return a[:] + ['foo']

If you have nested lists or other things like that, you'll probably want to look at copy.deepcopy to make the copy instead of the [:] slice operator.