I’ve invested sometime into EMF-Databinding to add a new quite interesting feature i guess. Currently we have to problem that if your nested path crosses a multi-valued feature (=java.util.List) at some point the only solution today is to create a volatile transient feature which observes your EList and fire change events but this really clutters your Ecore-Model.

Let’s take a look at an example model

you’d like to present in an UI like this:

Until EMF 2.7M7 you’d have to modify your EMF-model like this:

So that you could e.g. write something like this to get access to the private address’ city property:

import static at.bestsolution.e4.addressbook.model.addressbook.AddressbookPackage.Literals.*;

// ...

IEMFValueProperty mProp = EMFProperties.value(FeaturePath.fromList(PERSON__PRIVATE_ADDRESS,ADDRESS__CITY));

// or in longer builder type syntax
IEMFValueProperty mProp = EMFProperties.value(PERSON__PRIVATE_ADDRESS).value(ADDRESS__CITY);

With the new feature I’ve added to IEMFListProperty#value(ListElementAccess) one now does not have to create those volatile transient features any more but can write the long form like this:

IEMFValueProperty mProp = EMFProperties.list(PERSON__ADDRESSES).value(
  new ElementAccessImpl(AddressType.PRIVATE)
);

// ...
private class ElementAccessImpl extends ListElementAccess<Address> {
 private AddressType type;

 public ElementAccessImpl(AddressType type) {
  this.type = type;
 }

 @Override
 public int getReadValueIndex(List<Address> list) {
  int i = 0;
  for (Address o : list) {
   if (o.getType() == type) {
    return i;
   }
   i++;
  }
  return -1;
 }

 @Override
 public int getWriteValueIndex(List<Address> list) {
  int i = 0;
  for (Address o : list) {
   if (o.getType() == type) {
    return i;
   }
   i++;
  }
  return -1;
 }
}

I’d like to note that this feature is an experimental one and we don’t guarantee to break it e.g. by pushing it upstream to Eclipse Databinding but you are free to give it a try and report usefulness, problems, like, dislike, … .

BTW did you notice that the screenshot from the above application was taken from a Swing-Application? How can that be? Isn’t Eclipse Databinding (and because of that EMF Databinding ) only useful within SWT driven apps (e.g. Eclipse RCP ones)?

Without saying too much: No – because many core Eclipse technologies OSGi, Databinding, EMF, Eclipse 4 Application Platform to name some can be used with any UI-Technology