[Avocado-devel] Make optional interfaces implementation for plugin system.

[Andrei Stepanov]

Hello.

Currently Avocado Plugin System requires to implements all virtual
methods in plugins. Can we remove this restriction? RFE: Allow to
implement only necessary interfaces for plugins. Just skip their
invocation of absent methods in plugins?

1. This will allow as easily add new methods to existing Core Interfaces:

http://avocado-framework.readthedocs.io/en/latest/api/core/avocado.core.html#module-avocado.core.plugin_interfaces

Otherwise, any new interface extension to Core will force us to
rewrite __ALL__ plugins, which makes Avocado quite inflexible for
upgrading and for external plugins.

2. Allow for plugin-developers implement methods they require.

Thanks.