Instance-Specific Behavior for the Working Smalltalker

Abstract: The notion of class, whose significance cannot be underestimated, is not as essential as the concept of behavior. Notwithstanding, in most Smalltalk dialects objects get their behavior from their classes. In the last few years the emergence of Traits has made it even clearer that protocols should be independent from shape (state). However, in practice, it is rare (if not impossible) to find examples of Smalltalk systems that make use of instance-specific behavior. Digitalk demonstrated one decade and a half ago that a minimal change in the architecture of objects enables that possibility with ease and expressiveness. Surprisingly, from a practical viewpoint the feature has remained almost rhetoric. In this talk I will explain why classes should not be placed between objects and behaviors, as well as showing a number of applications whose usefulness for the working Smalltalker has been validated along five years of daily experience.

Bio: After working as a Smalltalk advisor for several companies in Argentina, Brazil and Chile, I became Director of Development at Caesar Systems in 2001. In 1997 I co-founded SUGAR, the Smalltalk User Group of Argentina and the MathMorphs Squeak User Group; starting in 2007, I'm the president the organizing board for the Annual Argentine Smalltalk Conference.