Pythonic way 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

Alternatively to Martijn's fine answer, you could chain or. 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

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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