[riena-dev] UnboundPropertyWritableList - Can we remove it?

[Elias Volanakis <elias@xxxxxxxxxxxxxxxxx>]

Hi Riena committers,

I am questioning the purpose of UnboundPropertyWritableList (=UPWL).

Currently UPWL insulates a list kept in the model from the list kept
in the ridget (see details below). My preference would be to
completely remove UPWL, and instead modify the list-based ridgets
(table, tree, list) to do the "insulation" internally.

My motivation is, that relying on a non-standard class (UPWL) to get
that insulation is not practical, because most developers will use the
default mechanisms (BeansObservables / PojoObservables / WritableList)
and miss UPWL:

listRidget.bindToModel(new WritableList(days, MyNode.class),
MyNode.class, columnPropertyNames, null);

instead of:

listRidget.bindToModel(new UnboundPropertyWritableList(new
ListBean(days), ListBean.PROPERTY_VALUES), MyNode.class,
columnPropertyNames, null);

Let me know what you think about removing it.

Elias.



--- Full details for the interested ---

I've compared UPWL with PojoObservables.bindList(...) /
BeansObservables.bindList(...) / new WriteableList(list, clazz). The
only difference I found between the default mechanisms and UPWL, is
that the latter does not automatically 'register' modifications to the
underlying list:

Standard Databinding:

IObservableList input = BeansObservables.observeList(bean,
ListBean.PROPERTY_VALUES);
input.toArray().length; // returns N
bean.getList().add(foo);
input.toArray().length // returns N + 1

Riena UPWL:

UnboundPropertyWritableList upwl = new UPWL(bean, "getter")
upwl.toArray().length; // returns N
bean.getList().add(foo);
upwl.toArray().length // still N -- this is useful for ridgets, but we
could do it ourselves

We use this behavior to insulate the data kept in the ridget, until
#updateFromModel() is invoked:

public void updateFromModel() {
  ...
  if (rowObservables instanceof UnboundPropertyWritableList) {  // not
so nice...
     ((UnboundPropertyWritableList) rowObservables).updateFromBean();
  }
  ...
}

If you want to experiment see attached snippet.

I think it would be better to add the "insulation" behavior to the
appropriate ridgets (for example via a helper class) instead of
relying on the custom type UPWL (implements IObservable).

Elias.

Attachment: SnippetTableRidget.java
Description: Binary data