multiple input types ("either / or") for option in python click

Question

Is it possible to specify two input types for a click.option, one of which the supplied value has to be in?

In a normal python function with typing, I'd declare it like so:

from typing import Union

def fun(x: Union[int, str]):
    if isinstance(x, str):
        x = int(x)
    return x**2

so x should be either an int or str.

In click I want to achieve the same thing, just with the addition that the script fails when the input type isn't in the defined ones.

I've tried

@click.option('-x', type=(click.INT, click.STRING))

but that seems to be only for occasions with multiple arguments.

Shoat

if you want it to convert string to int then maybe simply use int(variable) without checking type. If you use int(integer_number) then you get the same integer number. If you use int(string_number) then you get value converted to integer number. – Allan

@Allan this is just a toy example - in the real application, the two types would be a file or the already parsed contents of the file – Shoat

I don't use ``click` and I don't know how you want to recognize file and context - for Python both would be only strings. I would rather use two different variables for this - ie. -f for file and -t for text/content - first function (assigned to -f) would load file and run second function (assigned to -t). – Allan

Answer 1

Click does not directly support Union option/argument types (unlike its Tuple type support). It has been raised as a feature request at least twice (1, 2), but in both cases these have been closed with the advise to use a custom param type instead.

    class Union(click.ParamType):
    def __init__(self, types):
        self.types = types

    def convert(self, value, param, ctx):
        for type in self.types:
            try:
                return type.convert(value, param, ctx)
            except click.BadParameter:
                continue

        self.fail("Didn't match any of the accepted types.")

The click-param add-on module also provides a union type called FirstOf

    @click.option('-x', type=FirstOf(click.INT, click.STRING))

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