CODEWITHSUNDEEP
python-3.x
4thSpace
4thSpace

Reputation: 44352

Is return keyword needed in non return functions?

I see some examples where return is the last statement in a function that doesn't return anything. Is this needed in Python 3.x?

def myfunc():
  result = 1 + 1
  return

Upvotes: 0

Views: 55

Answers (3)

Terry Jan Reedy
Terry Jan Reedy

Reputation: 19174

As others said, "No". For a function that mutates the input or causes a side-effect, return or return None should be omitted, unless needed for early exit, in which case I would use return. However, I might use return None here:

def pos(x):
    if x > 0:
        return x
    else:
        return None

This could be condensed to this:

def pos(x):
    return x if x > 0 else None

Upvotes: 0

Łukasz Rogalski
Łukasz Rogalski

Reputation: 23233

Return statements are not mandatory, if function exits without any return statement, None is returned.

Proof:

Quoting official docs, namely Calls and The return statement:

About return:

return leaves the current function call with the expression list (or None) as return value.

About calls:

A call always returns some value, possibly None, unless it raises an exception. How this value is computed depends on the type of the callable object.

If it is a user-defined function:

The code block for the function is executed, passing it the argument list. The first thing the code block will do is bind the formal parameters to the arguments; this is described in section Function definitions. When the code block executes a return statement, this specifies the return value of the function call.

As we can conclude from docs - all functions implicitly returns None, unless explicit return statement is executed.

Upvotes: 1

AMACB
AMACB

Reputation: 1298

If the last statement in a function is return, then it returns a value. If there is no return statement, it does not return anything.

Upvotes: 0

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