Passing Python slice syntax around to functions

Question

In Python, is it possible to encapsulate exactly the common slice syntax and pass it around? I know that I can use slice or __slice__ to emulate sl

Answer 1

In short, no. That syntax is only valid in the context of the [] operator. I might suggest accepting a tuple as input and then pass that tuple to slice(). Alternatively, maybe you could redesign whatever you're doing so that get_important_values() is somehow implemented as a sliceable object.

For example, you could do something like:

class ImportantValueGetter(object):
    def __init__(self, some_list, some_condition):
        self.some_list = some_list
        self.some_condition = some_condition

    def __getitem__(self, key):
        # Here key could be an int or a slice; you can do some type checking if necessary
        return filter(self.some_condition, self.some_list)[key]

You can probably do one better by turning this into a Container ABC of some sort but that's the general idea.