So, to sum up what I said in the previous PR:

• We need a DocumentAware Interface which declares getDocument and setDocument
• We need a DocumentAwareTrait which implements these two methods
• The MVCFactory needs to implement the DocumentAware interface and use the trait
• The AbstractView needs to implement the DocumentAware interface and use the trait
• The MVCFactory service provider needs to push the document to the MVCFactory instance
• The MVCFactory instance needs to push the document to the View instance in createView

Together with what I am seeing in the PR this would strike a good balance between b/c and forwards-looking, cleaner code. We no longer need to push a document from the Controller unless we are trying to do something weird. The document drips from the DI Container via the component service provider, MVCFactory service provider and MVCFactory itself into the View. The View also has a setDocument method making it (more) testable. The magic getter and setter in the View ensure nothing breaks in 5.x but does complain that the legacy code must go away. Everyone's happy and Joomla moves forward. Happy times all around.

MVCFactory is more tricky because the legacy factory has to be taken into account too. I'd rather leave that for another PR I think and have done the stuff on the abstractview and left the injection in the controller for now

if ($view instanceof DocumentAwareInterface) {
   $view->setDocument($document);
}

Fully b/c. We are using this pattern already in Joomla 4.2, IIRC to push the application to the Controller (off the top of my head, I didn't check the codebase, I'm about to go to bed).

Yeah yeah I get it - if you look I updated the controller code to that initially. I can add it in addition to the mvc factory. But legacy mvc factory wouldn’t have it which makes removing it from the controller (which was our aim hard). I could probably drop it in both classes but it’s not clear to me if there would be other issues - which is why I’m nervy about moving that part around - and you know I’m generally more liberal about changes than you are ?

There's a few missing class properties that this latest code identified beyond the layouts which i've just direct backported to 4.3 with #38939

We need to add the __set and __get intro 4.3 for deprecation warning, maybe with the same pr #38939

Also is it possible to introduce a legacy class which could be loaded by the b/c plugin which has the __set, __get (cmsobject) functions and overloads the default view?

@wilsonge can you fix the merge conflicts please

Done. Because we've merged the DocumentAware Interface and trait into 4.4 since I wrote this some of the changes around where we call getDocument() look very trivial - but that's just cause me and Allon both put them into different places when writing the code independently. There's still some other changes in here (e.g. the reclassing of the CategoryFeed parent) and also removing the concept of helpers.

This pull request has been automatically rebased to 5.1-dev.

This pull request has been automatically rebased to 5.2-dev.

This pull request has been automatically rebased to 5.3-dev.