Sunday, November 11, 2007

A Happy Diversion

I was smitten with my quick snippet of code for my Monticello window in a flap. As with all little things in Squeak, it's hard to just stop. You're always thinking of little things or tools that would be nice. Everything in Squeak is easily explorable and changeable. It's too much fun to search and see the results of your labor instantly. Addictions are not pretty.

Another idea came to me. The tab for my Monticello flap was boringly called "Monticello". What a waste of real estate. My second problem was that I'm always getting confused at which project I'm in. I normally use different background colors to make it easy. But, I still get confused. I was blessed with a small brain. I curse it everyday. What is a poor little Squeaker to do? I thought I could put the name of the current project on the Monticello tab instead of the one it has. I wondered how hard would that be? And off I went...

How can I do that? I could change the tab name when the project changes. Eureka! That's what I will do. I remembered I wrote a little utility to change background images and I had to know when the current project changed. I started my hunt there and event handlers are available via the morphic world to know when a project is entered or exited. We only care about when a world is left. Why? The event handlers has to be registered on the world itself and we don't want to have to keep track of every project and world. It's easier to put a handler on the current project and know when it is left.

Let's start with this method for setting the world we're currently in:
world: aMorph 
world == aMorph ifTrue: [^ self].
world ifNotNil: [world removeActionsWithReceiver: self].
world := aMorph.
world ifNotNil:
[self changeTextOnTab.
world
when: #aboutToLeaveWorld
send: #leavingWorld
to: self]

Basically, this method removes all events from the old world since we will not care about it any longer. Then, we change the text on our tab and add our event handler. Next, how do we change the text on the tab? In the menu for a tab, is an item to change the name of the tab. Using the handy morphic handles, I inspect the menu item itself and find the method it will call when it is invoked. Here's the code I came up with:
changeTextOnTab
self monticelloFlapTab ifNotNilDo: [:tab | tab changeTabText: Project current name]

The simple method changeTabText: does all of the magic. We just get the name of the current project. I haven't showed you how to get the tab itself. I look through the methods on the class side of Flaps to reveal its magic:
monticelloFlapTab

^Flaps globalFlapTab: 'Monticello'

The good news is that it will always find the flap this way no matter the name. The only thing left is to what to do during the handling of leaving the current world. The dilemma now is how do we know the next world? Some more digging and we can be ask ed to be called later. Perfect. Here's the code for the handler:
leavingWorld
WorldState addDeferredUIMessage: [self world: Project current world]

And that's it! The same method can be called to seed our initial world as well. Now, a quick glimpse to the bottom of the screen gives my project name. Easy. Now, I can get back to updating my Seaside presentation.

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