Add types to duration.py

[InvincibleRMC]

Adds types to duration.py. Also adds an RCLDuration Type/Object Alias so type inference can be on the _duration_handle.

[InvincibleRMC]

The problem with that solution is without making some custom type alias mypy, and pylance have to treat _rclpy.rcl_duration_t as type Any which weakens the type inference. For example since the _duration_handle is type Any it cannot reason about the type of the nanoseconds field.

rclpy/rclpy/duration.py:44: error: Returning Any from function declared to return "int" [no-any-return]

@property
    def nanoseconds(self) -> int:
        return self._duration_handle.nanoseconds

[fujitatomoya]

@InvincibleRMC thanks for working on this. the reason i do not start CI is to wait for 2nd review. once we have 2nd approval, i will start the CI. (So are other PRs)

[InvincibleRMC]

No problem. Thanks so much for the prompt reviews.

[fujitatomoya]

CI:

• Linux
• Linux-aarch64
• Windows