Using Generics for messages

[InvincibleRMC]

First Draft.

[InvincibleRMC]

Noticed bug in protocol definitions working on a fix.

[InvincibleRMC]

Until this gets merged https://github.com/ros2/rosidl_python/pull/205 the type of all messages/services/actions have to be inferred as Any due to PEP 561. Because messages are all inferred to be Any It won't currently alert user about putting in the wrong message type. But I tested it by adding a py.typed file into std_msgs it correctly warns the user about different messages.

[InvincibleRMC]

Limited scope to Generics for publishers and subscribers only because couldn't get generics of services and clients working the way I wanted.

[sloretz]

Mini CI just to see what happens (repos file build: --packages-up-to rclpy test: --packages-select rclpy)

Linux:

[sloretz]

CI (repos file build: --packages-up-to rclpy test: --packages-select rclpy)

• Linux
• Linux-aarch64
• Windows

[sloretz]

Thank you for the PR!

[InvincibleRMC]

Thank you for the PR! @sloretz Would it be possible to backport this and future typing changes into Jazzy as well?

[sloretz]

Seems safe to back port to me

@mergifyio backport jazzy

[clalancette]

Seems safe to back port to me

While I'm OK with backporting this, I'm going to suggest we hold off on doing it until after Jazzy is released. That way we can be certain that only critical bugfixes are going in at this time.

[InvincibleRMC]

Seems safe to back port to me

While I'm OK with backporting this, I'm going to suggest we hold off on doing it until after Jazzy is released. That way we can be certain that only critical bugfixes are going in at this time.

Seems very reasonable.