Different number of return values in Python function

Question

Is it okay/good practice to return different number of return values from a function in Python? If yes, how should the caller handle the return values? e.g.

def func():
    if(condition_1):
        return 1,2
    if(condition_2):
        return 1
    if(condition_3):
        return 1,2,3,4

Note: condition_1,condition_2 and condition_3 are local to the function func so the caller has no idea how many values will be returned.

Answer 1

Is it pythonic for a function to return multiple values? have a great explanation in this.

But in your case, it depends on your use-case. If you know how to handle returning data, then there is no problem in using this. Like:

def func():
    if(condition_1):
        return a,b
    if(condition_2):
        return (a, )
    if(condition_3):
        return c,d,e,f
    if(condition_4):
        return a,b

vals = func()
if len(vals) == 2:
    # We are sure that we will get `a,b` in return
    do something ...
elif len(vals) == 3:
    ...

In example above, function that will process vals tuple knows how to handle returning data according to some criteria. It have 2 return possibilities that returns the same data!

If you know exactly how to handle data, then it is ok to go with different number of returns. The key point in here is functions do a single job. If your have problems in recognizing the return values, then your function is doing more than one job or you must avoid using different number of arguments.