Fixed message filter api

[ahcorde]

Related with this PR ros2/message_filters#132

[ahcorde]

There is an issue with rosdistro and branches. The problem is described here #458

If we merge this PR we will break humble, iron and jazzy deb builds

[clalancette]

To the maintainers here: it is usually our policy to not hard-break API like this in the ROS 2 core. We inadvertently did that when we merged in ros2/message_filters#129 ; we have a revert PR open in ros2/message_filters#132. However, we do eventually want to move in the direction of deprecating the current API and moving to a new one.

What's your feeling here? Would it be a lot better for you if we maintained the current API, and then somehow figured out how to move to a new one?

[SteveMacenski]

ros2 targets Rolling, humble/iron are branched separately. I don't think this is a problem, no?

[clalancette]

ros2 targets Rolling, humble/iron are branched separately. I don't think this is a problem, no?

It doesn't look like that is the case currently; all of Humble, Iron, Jazzy, and Rolling are using the ros2 branch:

• https://github.com/ros/rosdistro/blob/08be95e0407cf768d4b37a6e36a99b0d741634c8/humble/distribution.yaml#L5655
• https://github.com/ros/rosdistro/blob/08be95e0407cf768d4b37a6e36a99b0d741634c8/iron/distribution.yaml#L4399
• https://github.com/ros/rosdistro/blob/08be95e0407cf768d4b37a6e36a99b0d741634c8/jazzy/distribution.yaml#L4435
• https://github.com/ros/rosdistro/blob/08be95e0407cf768d4b37a6e36a99b0d741634c8/rolling/distribution.yaml#L4369

[SteveMacenski]

See #458

[clalancette]

See ros2/message_filters#132 (comment) , where we reverted the problematic change for now. We'll probably move back in that direction, so this PR will eventually be needed; up to you whether you want to leave this open for now or close it, and we can reopen later.