on Dashing: f-Strings breaking support with Python 3.5

[potentialdiffer]

Bug report

Required Info:

• Operating System:
  • Debian 9
• Installation type:
  • from source
• Version or commit hash:
  • dashing up from 0.7.7
• DDS implementation:
  • Fast-RTPS

Steps to reproduce issue

Compiling package from source on systems with Python 3.5, e.g. Debian 9, Raspbian Stretch ...

Expected behavior

Successful compilation.

Actual behavior

Failing compilation due to syntax error caused by f-Strings.

Traceback (most recent call last):
  File "bin/ros1_bridge_generate_factories", line 11, in <module>
    from ros1_bridge import generate_cpp
  File "/work/ros2_dashing/src/ros2/ros1_bridge/ros1_bridge/__init__.py", line 821
    f"message '{ros2_msg.package_name}/msg/{ros2_msg.message_name}' "
                                                                    ^
SyntaxError: invalid syntax
make[2]: *** [generated/get_factory.cpp] Error 1
make[1]: *** [CMakeFiles/ros1_bridge.dir/all] Error 2
make: *** [all] Error 2
---
Failed   <<< ros1_bridge [31.2s, exited with code 2]

Summary: 0 packages finished [34.2s]
  1 package failed: ros1_bridge
  1 package had stderr output: ros1_bridge

Additional information

We experience compilation issues as of 01b55fa with f-Strings which where introduced in Python 3.6 and are therefore not supported with earlier Python versions. [1]
REP-2000 however states Python 3.5 as dashing's minimum requirements. [2]

A workaround is to fix the package to ros1_bridge version 0.7.6. Dashing support ends this May. I am not sure how relevant this is, but wanted to document it anyway.

[1] https://www.python.org/dev/peps/pep-0498/
[2] https://www.ros.org/reps/rep-2000.html#dashing-diademata-may-2019-may-2021

[clalancette]

Thanks for the report. It looks like it should be easy enough to use one of the other string methods for Dashing so that this doesn't happen. Would you mind opening a pull request to the dashing branch fixing it?

[clalancette]

This was fixed by #306, so closing.