Roger Whitcomb created PIVOT-1011:
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Summary: Move ListenerList implementations of interfaces into the
interface itself
Key: PIVOT-1011
URL: https://issues.apache.org/jira/browse/PIVOT-1011
Project: Pivot
Issue Type: Improvement
Components: core-collections, core-util, web, wtk, wtk-terra
Environment: All
Reporter: Roger Whitcomb
Assignee: Roger Whitcomb
Priority: Minor
A universal paradigm in Pivot is to have a "listener" interface for a class or
data structure that is used to notify listeners of changes in the class/data.
There is then an "Adapter" static class in the interface file that implements
the interface with default implementations. Then there is a very separate
enclosed static class that implements the "ListenerList" interface of that
listener interface. And usually (or always) this "listener list" class is
defined/used only in the class that needs to notify the listeners. However,
this class must be very parallel to not only the interface itself, but also the
"Adapter" class, and yet it is in a different place.
So, it seems somewhat reasonable to move all these "listener list" classes into
the interfaces themselves, so all three related things are located in the same
file. A preliminary POC of this concept was done with "Query.java", and
"QueryListener.java" and it looks good.
This doesn't seem to require changes to client code, because the accessor
methods only refer to "ListenerList<....>" and not to the listener list class
itself (in order to be more general, of course), but which helps us to hide the
implementing class away inside the interface.
I will attach the diff of the POC, to hopefully make this more clear. It may
seem a somewhat nebulous concept, but the idea is to keep "like things"
together for clarity.
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