Setup and Teardown plug-ins

[mottosso]

Goal

Enable preparation and handling of the initial and final stages of the publishing pipeline.

• Related Prompt failed message at the end if any error occurred after validation (default test) pyblish-qml#344

Motivation

At the moment, if processing fails in response to a failed test, there's little you can do. If system-wide state was changed during processing - such as files having been extracted, database written to - you aren't given a change to clean things up.

To balance this "teardown" process, we'll also have a "setup" that runs first, regardless of plug-in order. To setup database connections and other things relevant to the whole test, and later torn down in the tearndown plug-in.

Implemenation

from pyblish import api

class MySetup(api.ContextPlugin):
  ...

class MyTeardown(api.ContextPlugin):
  def process(self, context):
    if any(r["error"] for r in context.data["results"]):
      # do cleanup

api.register_setup_plugin(MySetup)
api.register_setup_teardown(MyTeardown)

[tokejepsen]

api.register_setup_teardown(MyTeardown)

Would this be better with api.register_teardown_plugin(MyTeardown) ?

[mottosso]

Oh, yes, you're right. Typo.

[davidlatwe]

Instead of registering as teardown plugins, what about adding an attribute teardown ?

class MyTeardown(api.ContextPlugin):
    teardown = True

And these kind of plugins will also guaranty to run even user pressed the GUI Stop button.
☝️ This is something I might need for pyblish_qml.