[platform-ui-dev] Proposal - code path consistency throughout UI parts

["Randy Hudson" <hudsonr@xxxxxxxxxx>]

I'm not comitter, but I'm proprosing the following anyway because I think
it should be proposed.

Throughout many of the UI parts, (EditorParts, ViewParts, and Pages such as
the OutlinePage), there is an assumed (by me, although sometimes even by
the JavaDOC) sequence of events.  What's worse, is that these assumption
hold true 95% of the time, and developers may not stumble accross the 5%.
For example, I didn't know about most of them until after the WSAD Tech
Preview.

For example, I had assumed the following:

1) When dispose is called on my OutlinePage, the control is still valid.
2) dispose() gets called on my EditorPart some time in the future after
createControl(Composite) is called.
3) setInput() and createControl() are called in succession (meaning
syncronously, such that the two would complete before any asyncronous
things have a chance to run) on my EditorPart when opening a resource.
4) my ViewPart is created and createControl() is eventually called.


For a long time, these assumptions held.  In fact, developers may get
through an entire development cycle without encountering the events that
cause them to fail.  They are:
A) Closing the OutlineView while your Editor is open.
     1) doing this will cause your page's control to get disposed before
the page is disposed.
B) Shutting down eclipse with an open editor in a non-foreground
perspective, and then restarting Eclipse.
     2) createControl will never get called on your EditorPart unless you
bring that background perspective to the front
     3) setInput will get caled on your EditorPart, but its control will
not get created unless you switch to that perspective.
     4) ViewParts behave similar to EditorParts, if they are in the
background, no controls are created.

These inconsistencies caused me problems.  There could be more out there
that others know about.  I think an effort should be made to make the
"chain-of-events" as consistent as possible, especially when the exceptions
to the rule are difficult to discover.

If my EditorPart is loaded as part of a background perspective, then my
plugin was initialized.  The optimization gains of not creating my editor's
control are negligible when compared to the average plugin startup time abd
the hydration of the editor's input.

-Randy