Introducing a Safe Navigation Operator in Python

[ncoghlan (Alyssa Coghlan)]

@mikeshardmind

I think a result type is the only way I’d support syntax for this kind of path traversal handling (and vice-versa, I don’t think a standard library result type is useful without syntactic support), but I don’t find the API proposed in that thread compelling, I think the much fuller result from the library which has been linked a few times by different people now that is closer to rust’s in terms of interface is needed to ensure error handling when used that way is something which remains idiomatic.

Yeah, there would definitely need to be significant iteration on the exact design of a built-in result type.

A couple of notes that occurred to me just in the time since my last post:

• the safe navigation operators likely would need to be result-aware, so they would compose nicely with methods that were defined as returning results instead of eagerly raising exceptions
• rather than reraising the original exception directly, or raising an entirely new exception with no link to the original, results would need to use the raise new_exc from saved_exc syntax, so both tracebacks would be reported correctly

And just to confirm, the library you’re referring to is the one mentioned in
Introduce Result class to allow a modern representation of failure cases - #2 by johnthagen ?