Consider three functions:
def my_func1():
print "Hello World"
return None
def my_func2():
print "Hello World"
return
def my_func3():
print "Hello World"
They all appear to return None. Are there any differences between how the returned value of these functions behave? Are there any reasons to prefer one versus the other?
5 Answers
On the actual behavior, there is no difference. They all return None and that's it. However, there is a time and place for all of these.
The following instructions are basically how the different methods should be used (or at least how I was taught they should be used), but they are not absolute rules so you can mix them up if you feel necessary to.
Using return None
This tells that the function is indeed meant to return a value for later use, and in this case it returns None. This value None can then be used elsewhere. return None is never used if there are no other possible return values from the function.
In the following example, we return person's mother if the person given is a human. If it's not a human, we return None since the person doesn't have a mother (let's suppose it's not an animal or something).
def get_mother(person):
if is_human(person):
return person.mother
else:
return None
