Avoid ‘if x: return x’ in Python – Pythonic Ways to Avoid ‘if x: return x’ Statements

if-statementpython

I have a method that calls 4 other methods in sequence to check for specific conditions, and returns immediately (not checking the following ones) whenever one returns something Truthy.

def check_all_conditions():
    x = check_size()
    if x:
        return x

    x = check_color()
    if x:
        return x

    x = check_tone()
    if x:
        return x

    x = check_flavor()
    if x:
        return x
    return None

This seems like a lot of baggage code. Instead of each 2-line if statement, I'd rather do something like:

x and return x

But that is invalid Python. Am I missing a simple, elegant solution here? Incidentally, in this situation, those four check methods may be expensive, so I do not want to call them multiple times.

Best Answer

Chain or statements. This will return the first truthy value, or None if there's no truthy value:

def check_all_conditions():
    return check_size() or check_color() or check_tone() or check_flavor() or None

Split it into multiple lines like this:

def check_all_conditions():
    return (
        check_size()
        or check_color()
        or check_tone()
        or check_flavor()
        or None
    )

Demo:

>>> x = [] or 0 or {} or -1 or None
>>> x
-1
>>> x = [] or 0 or {} or '' or None
>>> x is None
True
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