How to properly import a plugin?

[Chandan Singh <chandan chandansingh net>]

Hello,

I was trying to extend one of the Element Plugins but ran into an issue quite early on. I'm hoping that someone on this list might have some answers.

I was trying to naively extend a plugin (DpkgElement specifically) like so:

```

from buildstream.plugins.elements.dpkg_build import DpkgElement

# Element implementation for the 'my_dpkg_build' kind.

class MyDpkgElement(DpkgElement):

    pass

```

While the above import statement worked successfully when I was trying it out in a python shell, it doesn't seem to work when it is run as part of the `bst build` command. Upon doing that, I get an error message like so (truncated):

```

...

  File "/usr/local/lib/python3.5/dist-packages/pluginbase.py", line 410, in plugin_import

    fromlist, level)

  File "/src/plugins/elements/bb_dpkg_build.py", line 1, in <module>

    from buildstream.plugins.elements.dpkg_build import DpkgElement

  File "/usr/local/lib/python3.5/dist-packages/pluginbase.py", line 410, in plugin_import

    fromlist, level)

ImportError: No module named 'pluginbase._internalspace._sp606628c88e67eb4efbaa8e0085714209.elements'

```

Is there another way of importing plugins correctly, or is it something that works as designed and plugins are not supposed to be imported?

--

Regards,

Chandan Singh

https://chandansingh.net/