[Rails-devel] Rails2.0 : Added PortfolioNG and Wallet classes

[Stefan F. <ste...@we...>]

All:
further update about the progress on Rails2.0 (if anyone follows that 
already). This update added new Portfolio and Wallet classes which are 
based on the general State class.

Overall Status:
The state package should now be close to feature complete, however
expect frequent updates and fixes.
The model package now contains a lot of classes and interfaces 
(everything around Owner...) which will be removed eventually.

Next step is removing remaining errors and bugs.
After this the Context/Item setup will be implemented throughout Rails.

Stefan


More details:
As I was not convinced by my previous refactoring of the Portfolio and 
Ownership approach, I did a fresh start there. For this I decided to 
create a basic Portfolio class that is a first class child of State.

It is currently called PortfolioNG, however will be renamed to Portfolio 
later on. It allows storing of OwnableItem(s) and is basically a thin 
wrapper around an ArrayListMultimap. However it ensures that adding to a 
portfolio always remove the item from its previous portfolio. The map 
keys have to implement the new Interface ItemType.

An example with Train objects will make this clear:

A portfolio will be defined as
Portfolio<Train> portfolio = Portfolio.create("Trains");

Then a train object train can be moved into that portfolio using

portfolio.moveInto(train);

and will be automatically removed from the previous owning
portfolio.

For trains the TrainType will be the key that is used in the portfolio 
so one can use

portfolio.getItems(trainType);

to retrieve all trains from the portfolio that belong to the specified 
trainType.

In parallel there is a Wallet class which is another subclass of State
which can store CountableItem(s). Again this is a thin wrapper this time 
around HashMultiset.

This works with a similar syntax, but it allows to store resources that 
comes in (integer) multiples, e.g. money. In principle it could also be 
used (in the longer run) for all objects (shares, tiles and even 
trains), where the individual items only differ in respect with to the 
owner.

For reference for the Collection types discussed above please refer to 
the collections of the Guava library (aka Google Collections).
See 
http://code.google.com/p/guava-libraries/wiki/NewCollectionTypesExplained