Python force tuple return type to required one use one line

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I have a function

function(input: str) -> Tuple[str, str]:

    return tuple(x for x in input.split(","))

The input is always 'value1, value2', however, I got an error message of: "Tuple[str, ...]", expected "Tuple[str, str]")

Is there anyway force the return type to the expected one just use one line of code?

tuples python-3.x list python
1 Answers

The interpreter has no idea how many elements x for x in input.split(",") will produce - from its perspective, input could be anything. Accordingly, it classifies the returned type as Tuple[str, ...].

To get it to use a return type of Tuple[str, str], which you marked the method as, you need to explicitly return exactly two elements:

def function(input: str) -> Tuple[str, str]:
    tup = input.split(',')
    return (tup[0], tup[1])

or otherwise, annotate the method differently.

as a one-liner you could use a list slice:

def function(input: str) -> Tuple[str, str]:
    return tuple(input.split(','))[:2]
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