lessons from Java, OOP

[Dar Scott]

On Nov 29, 2004, at 12:35 PM, Ivers, Doug E wrote:

> Perhaps many of the best scriptors among us implement OOP concepts 
> (consciously or not).  For example, custom properties might be a good 
> way to encapsulate data in a field (or other control).  The key here 
> would be to write "get" and "set" scripts in the field script and 
> never touch the data except by sending messages to these handlers.  If 
> you do this, please send me tips/advice.

I use custom properties in custom controls and in certain cards and 
stacks.  I write setProp handlers for these in most cases and getProp 
handlers in many cases.

Unfortunately, it is not possible to write such handlers for built-in 
properties, so I have to use names based on my own abstractions.  Also, 
I can't define a custom property named 'text' and use that as the 
default property as in fields and images.

For a custom control, the custom properties of the enclosing group 
completely define the state of the control in my style.  All 
interaction is through these.  I do not fiddle with the enclosed 
objects.  (When I'm obeying my rules, which is usually the case.)

I also do this for stacks and sometimes cards.  For example, a stack 
representing the printed page of an invoice might be specified by a 
collection of custom properties.  In some cases, most properties are 
design time (say margins) and only a few are runtime.

Often, actions are not appropriately state related and using custom 
controls may seem silly.  In these cases I define handlers that are 
called.  However, I find that state via custom controls tends to model 
how I think of the object in most cases and for most features.

Sometimes I share scripts among custom controls by using a stack 
library or an invisible group with a cute image on card 1 (which I call 
a badge) or both.

There are other issues with custom controls and I'm still experimenting.

I'm still learning and would be glad to hear of any insights that your 
Java experience provides.

Dar

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