Undefined 'now' variable in 'turtle_tf2_listener.py' tutorial

[songyuc]

I am attempting to follow along with the Using Time (Python) — ROS 2 Documentation tutorial. In the "1. Update the listener node" section, the tutorial instructs to edit turtle_tf2_listener.py and remove the timeout=Duration(seconds=1.0) parameter from the lookup_transform() call, and gives the following code:

trans = self._tf_buffer.lookup_transform(
to_frame_rel,
from_frame_rel,
now)

However, upon inspecting the turtle_tf2_listener.py source file, I noticed that the now variable is not defined anywhere in the file. Because of this, I am unable to successfully follow along with the tutorial.

I wanted to ask if this is an error in the tutorial, or if the source file has been updated and the tutorial has not? How should I proceed in order to successfully complete the tutorial?

I am using ROS 2 Iron.

Thank you very much for your assistance.

[jkaniuka]

Hi @songyuc, your suspicions were correct :wink: - source file was updated, but tutorial has not. You can simply replace now with rclpy.time.Time(). See details here :robot:

[clalancette]

We "fixed" this by removing the tutorial in #4384, so closing.