Tuesday, August 23, 2011

I've Inherited an Interesting Dilemma

Consider two browser screenshots. The first is the class side of AlphaBlendedIcons, with the needsComment method selected.

This second is the instance side of NameSpace, the needsComment method selected.

In both cases, if you invoke the menu of the selectors list, and choose the Hierarchy Implementors option, you get the following two results, respectively...

So what's the issue? The issue is the presence of ClassDescription in the Implementors browsers. Should it be there or not?

On the one hand we have the notion of "hierarchy." In RB land, a Hierarchy Browser is a pretty common thing. It is a limited view of classes always going as high as Object. If you are on the instance side, it tops at Object. If you are on the class side, it tops at Object class. From this point, where the term "Hierarchy" refers to a browsing view or scope, it is surprising to see these entries for ClassDescription here when you ask for Hierarchy Implementors. What you expect to see, is only methods that you'd find as you navigated around in the Hierarchy Browser.

Then there is a more pedantic side. It tends to be those who like to think of themselves as "I have ascended into the thirteenth circle of Smalltlak Uber-Knowledge." They know the zen-secret that there's a "crossing of the streams" that occurs at Object class. When a method is not found at Object class, the lookup for the method doesn't stop there, but continues up on the instance side at Class, then ClassDescription, then Behavior, and finally Object (instance). The little up/down arrows we place next to methods, even show this. If you look at the first one, it shows that there is a super implementor of needsComment for AlphaBlendedIcons, that is found farther up the search tree.

These two notions of "hierarchy" when viewed from the class side, are at odds with another. When someone sees that menu option, which kind of "Hieararchy" are they more likely to think about at that moment. Should it be left the way it is, but reword the menu option to be "super/sub implementors?" What would you want it to do?