When every path in a function has a return statement is it wrong to not use an else statement?

Question

I've been trying to get better at styling my code and making sure it's as readable as possible.

Would it be considered bad practice to skip the else and just have a return ?

For example with this:

if x == 1:
    return True
return False

Instead of:

if x == 1:
    return True
else:
    return False

This is often a local decision within your work group. If you want to improve your style, I recommend that you read through the PEP-8 guidelines. — Prune, Jun 30 '17 at 00:44
PEP-8 seems to be agnostic about this. There's one example with the first style, another with the second. — Barmar, Jun 30 '17 at 00:45
This is very opinion based, but I would just say `return x == 1` so that it's obvious and readable that we're returning whether or not `x == 1` or not — Davy M, Jun 30 '17 at 00:46
@DavyM I suspect this is a contrived example and is really part of multiple if/elif statements with a generalized fallthrough handler at the end. However, I've seen both ways in Pep8-linted code, so I would just be consistent within your team. — Alex Huszagh, Jun 30 '17 at 00:48
@Prune There is a thread about this very topic [over at Software Engineering](https://softwareengineering.stackexchange.com/questions/157407/best-practice-on-if-return). Wish we had cross site dupe closing. — Christian Dean, Jun 30 '17 at 01:30
@ChristianDean note that question uses C syntax, it could be that due to syntax / other language features, the answer could be different for different languages. — Baldrickk, Jun 30 '17 at 01:46
Closely related: https://stackoverflow.com/questions/44608516/what-is-the-difference-between-else-return-true-and-just-return-true/44608693#44608693. I point out a negligible difference in the byte code generated for each of the two in an answer there. — chepner, Jun 30 '17 at 03:06

Baldrickk · Accepted Answer · 2017-06-30T07:04:14.470

Both styles are valid, and the python style guide (PEP 8) does not specify a preference for either.

Whichever you decide to use, be consistent with it. This will result in code that is easier to read.

from PEP 8:

[…] code is read much more often than it is written. […] As PEP 20 says, "Readability counts".

A style guide is about consistency. Consistency with this style guide is important. Consistency within a project is more important. Consistency within one module or function is the most important.

Under Programming recommendations:

Yes:

def foo(x):
    if x >= 0:
        return math.sqrt(x)
    else:
        return None

def bar(x):
    if x < 0:
        return None
    return math.sqrt(x)

score 0 · Answer 2 · answered Jun 30 '17 at 01:18

I always returns directly when it does not impact.

I did not find reference about that, but here is my vision

Because some time you could have to do stuff like

for spam in bacon:
    if spam == egg:
        return spam

But if you want to avoid returning within the if statement you will have to do:

return_value = None

from spam in bacon:
    if spam == egg:
        return_value = spam
        break

 return return_value

Which result to the exact same result & execution but only add 3 non relevant lines so I finally think when this happen I always use the same rule: return directly.

The thing is to not go too deep with for / if / return, but that is not really the question here.

When every path in a function has a return statement is it wrong to not use an else statement?

2 Answers2