AW: where to put handlers?

[Richard Gaskin]

Devin Asay wrote:
> I have two objections to placing all handlers high in the message  
> hierarchy.
> 
> 1. It destroys the modularity/object-oriented-ish-ness of Revolution  
> stacks. If I create a particularly brilliant object (or at least a  
> complicated object that is "good enough") I often want to re-use it  
> in other projects. If I've separated the scripting from the objects  
> it becomes much more difficult.

But sometimes that modest effort can pay big dividends down the road.

For example, I have a table object that I use throughout many of the 
apps I write.  It has a lot of code, and parts are rather tricky, so if 
I replicated it I'd have a lot of replicated code and if I need to 
change it I'd have a lot of work applying those changes to each instance.

So instead I have as little code as possible in the group itself, and 
put most of the code in a library.  There's only one copy of the code, 
and maintaining and enhancing it is a breeze.


> 2. As a project grows in complexity, a stack script that contained  
> all handlers in the stack could easily swell to several thousand  
> lines. In this case it actually becomes *harder* to maintain, as you  
> must scroll or search through a huge script to find the handler  
> you're looking for.

True, so I break my code up into separate libraries, each dealing with a 
particular area of functionality (menu commands, file management, etc.).

In fact, menu commands are a good example of the benefit of centralizing 
code, since having them all in one shared library makes it easy to add 
contextual menus at any time.  If the code for menu handling were in the 
menu bar I'd either have to replicate it in the context menu, or use a 
lot of send commands.

Finding handlers is a job best left for the computer.  My script editor 
has had handler definition lookup for years, and Jerry's does too.  I'm 
sure Rev will catch up sooner or later as well.

So I agree with just about everything you wrote, but I'm not sure 
there's a One Size Fits All answer to this question.

Jerry's axiom is helpful, but the definition of "necessary" will change 
from context to context. ;)

-- 
  Richard Gaskin
  Managing Editor, revJournal
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