typeof¶

basedpython adds a typeof keyword that yields the static type of an expression in any annotation position:

b: int = 1

a: typeof b = 1                # `a: int`
def f(x: typeof b) -> typeof b: ...
cb: typeof b | None            # `int | None`

transpiles to:

from ty_extensions import TypeOf

b: int = 1

a: TypeOf[b] = 1
def f(x: TypeOf[b]) -> TypeOf[b]: ...
cb: TypeOf[b] | None

scope¶

typeof is a basedpython-only keyword: a .py file using it produces a parse error. when the next token cannot start an expression (e.g. typeof = 5), typeof is parsed as an ordinary identifier so existing python code that uses typeof as a name continues to parse

polyfill¶

typeof X lowers to ty_extensions.TypeOf[X]. there is no runtime equivalent — TypeOf is a type-checker-only construct evaluated by ty