Protocols in Python (til.simonwillison.net)

submitted 1 year ago by rglullis@communick.news to c/python@programming.dev

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[-] o11c@programming.dev 1 points 1 year ago

That still doesn't explain why duck typing is ever a thing beyond "I'm too lazy to write extends BaseClass". There's simply no reason to want it.

[-] lysdexic@programming.dev 1 points 1 year ago

I already explained it to you: protocols apply to types you do not own or control, let alone can specify a base class.

You just specify a protocol, specify that a function requires it, and afterwards you can pass anything to it as-is and you'll be able to validate your calls.

[-] o11c@programming.dev 1 points 1 year ago

and I already explained that Union is a thing.

[-] lysdexic@programming.dev 1 points 1 year ago* (last edited 1 year ago)

I'm not sure you understand that what a union does or does not do is completely irrelevant and besides the point. Python's protocols add support for structural subtyping, and enable both runtime and build-time type checks without requiring major code changes. Don't you understand what that means?