Pass parameter to plugin from parent model

[scpeters-test]

Original report (archived issue) by Lorenzo Rapetti (Bitbucket: lorrapetti).

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When using nested models, I have the necessity of changing the parameters of a plugin directly from the parent model SDF without changing the SDF of the model that is included (e.g. if I want multiple instances of the same model but with different parameters).

A possible solution is having a plugin that search for the configuration not only in the plugin SDF, but also looking a the parent model SDF using GetParent():
e.g.

original model

<model name="myModel">
  <plugin name="myPlugin" filename="myPlugin.so">
    <PluginConfiguration> ... </PluginConfiguration>
  </plugin>
  ...
</model>

overritten model

<model name="overritenModel">
  <configurationOverride plugin_name='myPlugin'> ... </configurationOverride>
  <include>
    <uri>model://myModel</uri>
  </include>
</model>

However, this is not feasible since it is not possible to add a custom SDF to a model.
A custom SDF can be add only in a (thanks to special class defined in plugin.sdf), so at the moment the solution works only using a dummy plugin that doesn't do anything:
overritten model

<model name="overritenModel">
  <plugin name='override_plugin' filename='dummy_plugin.so'>
    <configurationOverride plugin_name='myPlugin'> ... </configurationOverride>
  </plugin>
  <include>
    <uri>model://myModel</uri>
  </include>
</model>

It would be great to have a clean way to pass parameters to a plugin in a nested model. A good way might be having those parameters as element of the , and reading them from the plugin.

(original discussion in gazebo-yarp-plugin at robotology/gazebo-yarp-plugins#392)

[scpeters-test]

Original comment by Lorenzo Rapetti (Bitbucket: lorrapetti).

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• Edited issue description