Anonymous class¶

Anonymous record shapes already give a value shape without declaring a name for it: (x: int, y: int). A callable's own parameter list uses the same grammar, on the left of a function type's ->, whenever a function has no variadic zoning of its own:

(str, bool) -> R

— the type of a function like greet(name: str, loud: bool).

A / marks the end of a positional-only zone; a bare * marks the start of a keyword-only one — the same two markers an ordinary parameter list already uses, and both stay within this same, plain shape:

(c: int, /, a: int, *, b: int)

- c: int, / — positional-only. - a: int — ordinary: callable by position or by keyword. - * — the keyword-only zone begins. - b: int — keyword-only.

Every field here has a name, because every field here is one fixed, individually addressable slot — whether or not a caller can ever use that name. An ordinary or keyword-only field needs one because the checker has to know it to verify a keyword call. A positional-only field needs one for a different reason: callers can never use it, but the name is what marks it as one slot. The order — positional-only, then ordinary, then keyword-only — isn't a style rule: nothing can be keyword-only until the positional zone is finished.

A signature with an unbounded, unnamed tail — the case a decorator's generic forwarding needs, or a genuine overflow catch-all — extends this grammar further; see Parameters.

Class members covers the named kind's own vocabulary — fields, methods, getters, setters, and the rest.