Handling of "anon" names not consistent with roslaunch

[marco-tranzatto]

Hi all,

once more thanks for sharing this great tool.

I have been using it a lot lately and found a behavior mismatch with roslaunch about the usage of "anon" names for nodes.

I created a minimal example here.
The package contains two launch files:

• "anon_node_include.launch" which is a simple talker node whose name is name="$(anon talker)"
• "main.launch" which includes the file "anon_node_include.launch" two times.

If the user executes

roslaunch rosmon_anon_issue main.launch

Then the launch succeeds and there are two nodes with anonymous names:

$ rosnode list 
/rosout
/talker_rsl_l25_4797_5574635845418076715
/talker_rsl_l25_4797_7425401142298951921

On the other hand, if the user types

mon launch rosmon_anon_issue main.launch

Then the following error is reported:

Could not load launch file: /home/marcot/catkin_ws/src/launch_file_examples/rosmon_anon_issue/launch/anon_node_include.launch:6: node name 'talker_52666652' is not unique

@xqms any hints about this?

Thanks a lot for your help,
Marco.

[xqms]

That definitely sounds like a bug. Thanks for providing an example, that'll help in creating a test for it.

When I implemented $(anon XYZ), I thought that the same XYZ prefix should always resolve to the same node name. But it seems that this is only true at file scope, as demonstrated by your multiple-inclusion example.

I'll have time to look at this in more detail next week.

[xqms]

I found a smaller reproducing example, which shows some more interesting behavior:

<launch>
  <param name="test_1_global" value="$(anon test_1)" />

  <group>
    <param name="test_1_local" value="$(anon test_1)" />
    <param name="test_2_local" value="$(anon test_2)" />
  </group>

  <param name="test_2_global" value="$(anon test_2)" />
</launch>

In this case, we get from roslaunch:

test_1_global: test_1_martin_11923_1971446669036573556
test_1_local:  test_1_martin_11923_1971446669036573556 (same)

test_2_global: test_2_martin_11923_7236432865625322132
test_2_local:  test_2_martin_11923_5520981918244494059 (different)

It seems the effect of $(anon) is local, but the lookup is recursive into the parent scopes. Ordering also matters.

[marco-tranzatto]

Interesting! I didn't think about param names, since the wiki mentions only for nodes:

This is used for name attributes in order to create nodes with anonymous names [1]

what's your intention on this issue?

[1] Wiki, see "$(anon name)" section.

[xqms]

Interesting! I didn't think about param names, since the wiki mentions only for nodes:

Yes - <param> is just easier for me to test in the unit test framework ;-)

what's your intention on this issue?

I opened a pull request with a fix at #101. It requires a bit more system-level testing, though.

By the way, congrats on opening the 100th issue 🎉 😄

[marco-tranzatto]

I see your point about testing.

Never had this record before about the 100th issue xD

Again, thanks for sharing and taking care of this awesome tool!
Marco.