[Rails-devel] Suggested object model for core generic framework

[Stewart T. <wsr...@ho...>]

Brett,

As promised, you'll find atached my sketched out object model in UML for the 
core generic framework. Rather than try sending a Visio file, I'm sending a 
snapshot as a PNG file.

A few explanatory words are probably called for.

I've modelled "Bank", "Player" and "Company" as subclasses of a common 
"Entity" class. This allows inherited code to take care of common 
functionality and in particular relationships. "Stock" can be held by any of 
"Bank", "Player" or "Company" in some 18xx games. In 1841, IIRC, major 
companies can even hold stock in other companies. This brings an opportunity 
to write very simple code for functionality like dividends: some 
"payDividend" (with amount parameter) method on "Company" simply loops round 
all issued "Stock" (follows the "issues" relationship), calling a 
"payDividend" method on each "Stock" object, which pays the correct amount 
(adjusted for percentage share) to the owning "Entity" (follows the inverse 
"owns" relationship).

Similarly, all Stock trades can be implemented with a single method that 
changes the owner.

I've subclassed "Tile" into "VariableTile" and "FixedTile". My idea is that 
we represent all of the printed map hexes as instances of "FixedTile". This 
mean that they can all be drawn in GUI in the same way, and those printed 
portions of the map that can have tokens placed on them, or upgraded in 
later phases do not need to be treated as a special case. I've separated the 
"Tile" from the "Location", so that relationships with "Token" don't need to 
be adjusted when a tile is upgraded.

The "Round" hierarchy hanging off "Game" is really just a placeholder. If 
you want to keep an audit trail of player and company actions for future 
analysis or replay, then this is where I would put it in the object model.

I've split "Company" into "Major" and "Minor" because in some 18xx games, 
they are governed by different rules.

This is very much a first attempt at an object model. At this stage I've 
concentrated on the objects themselves and their relationships. I have made 
no attempt to fill in each object's attributes and methods.

If you have any questions please email me and I'll be happy to answer them.

cheers

Stewart