| from __future__ import annotations | |
| from typing import Callable | |
| from mypy.plugin import AttributeContext, Plugin | |
| from mypy.types import AnyType, Type, TypeOfAny | |
| class AttrPlugin(Plugin): | |
| def get_attribute_hook(self, fullname: str) -> Callable[[AttributeContext], Type] | None: | |
| if fullname == "m.Magic.magic_field": | |
| return magic_field_callback | |
| if fullname == "m.Magic.nonexistent_field": | |
| return nonexistent_field_callback | |
| if fullname == "m.Magic.no_assignment_field": | |
| return no_assignment_field_callback | |
| return None | |
| def magic_field_callback(ctx: AttributeContext) -> Type: | |
| return ctx.api.named_generic_type("builtins.str", []) | |
| def nonexistent_field_callback(ctx: AttributeContext) -> Type: | |
| ctx.api.fail("Field does not exist", ctx.context) | |
| return AnyType(TypeOfAny.from_error) | |
| def no_assignment_field_callback(ctx: AttributeContext) -> Type: | |
| if ctx.is_lvalue: | |
| ctx.api.fail(f"Cannot assign to field", ctx.context) | |
| return AnyType(TypeOfAny.from_error) | |
| return ctx.default_attr_type | |
| def plugin(version: str) -> type[AttrPlugin]: | |
| return AttrPlugin |