Method get_expr_by_position

mypy/checkstrformat.py:488–512

Get positional replacement expression from '{0}, {1}'.format(x, y, ...) call. If the type is from *args, return TempNode( ). Return None in case of an error.

(self, pos: int, call: CallExpr)

        return result

    def get_expr_by_position(self, pos: int, call: CallExpr) -> Expression | None:
        """Get positional replacement expression from '{0}, {1}'.format(x, y, ...) call.

        If the type is from *args, return TempNode(<item type>). Return None in case of
        an error.
        """
        pos_args = [arg for arg, kind in zip(call.args, call.arg_kinds) if kind == ARG_POS]
        if pos < len(pos_args):
            return pos_args[pos]
        star_args = [arg for arg, kind in zip(call.args, call.arg_kinds) if kind == ARG_STAR]
        if not star_args:
            return None

        # Fall back to *args when present in call.
        star_arg = star_args[0]
        varargs_type = get_proper_type(self.chk.lookup_type(star_arg))
        if not isinstance(varargs_type, Instance) or not varargs_type.type.has_base(
            "typing.Sequence"
        ):
            # Error should be already reported.
            return TempNode(AnyType(TypeOfAny.special_form))
        iter_info = self.chk.named_generic_type(
            "typing.Sequence", [AnyType(TypeOfAny.special_form)]
        ).type
        return TempNode(map_instance_to_supertype(varargs_type, iter_info).args[0])

    def get_expr_by_name(self, key: str, call: CallExpr) -> Expression | None:
        """Get named replacement expression from '{name}'.format(name=...) call.