[Cuis] ColorEditor updated

[KenD]

On Mon, 02 Nov 2015 15:58:26 -0500
"Dan Norton" <dnorton at mindspring.com> wrote:

>.. I was casting about for some name besides " #when:send:to: mechanism" for 
> use in a brief essay on PluggableListMorph Principles of Operation when I came across 
> Signals. I already wrote a paragraph on Dependency Mechanism.

I would talk about #when:send:to: as implementing the Observer Pattern.

> So, the simple principle here is to just use #when:send:to: and forget about or maybe 
> deprecate #changed: and #update:? 

Yes.  Let us work to eliminate #changed: !

> However, I see a problem common to dependency and #when:send:to: which is the 
> identification and explanation of the various symbols which are communicated as the 
> parameters for send: or changed: . When you're trying to design a model or view similar to 
> something already in existence, the tools are not much help with that.
> 
> I'm thinking maybe: document in comments? <rant>Nah. We don't do comments.</rant>

We should certainly add clarifying comments!

Your Comment Browser is a big help here.  Once people start using it more, comments will appear.

I suggest sending Juan a code update with an added "Open Comment Browser" Help menu item which autoloads the same way as TerseGuide.


However, class comments are not usually where design patterns show up.  8^|

In the case of #when:send:to: I suggest a slightly larger discussion around building paned windows which update dependent panes.

What constitutes good style?  What code patterns help?

Think "Useful Code Patterns" to augment "Useful Expressions".

You can do your own example, but looking at the ColorEditor:

ColorEditor>>buildMorphicWindow
	"Create a useful ColorEditor window"
	
	self layoutMorph beRow; " A row of columns"
		 separation: 6;
		 addMorph: self buildColorPaneColumn;
		 addMorph: self buildSliderColumn;
		 addMorph: self buildRadioButtonColumn;
		 color: self backgroundColor.
		
	self model when: #colorChanged send: #refreshColor to: self.
	
	^ self

So trying for good style (hey, I need to improve here too!) one uses: 

[Class]>buildMorphicWindow
    [Add (construct each pane).. to layout]
    [Add self or panes as observers]
  ^ self

Suggest
  Smalltalk browseAllImplementorsOf: #buildMorphicWindow
to see specific usage examples.

Of course, we will suffer some embarrassment as our real code is less than ideal. 8^(

But this is a great motivator to making our code better!  ;^)


$0.02
-KenD