Toolkits in First Year CS: A Pedagogical Imperative Richard Rasala College of Computer Science Northeastern University Boston MA 02115

Why Toolkits Are Necessary Input should be powerful and robust Text only is boring... we need graphics Graphics helps students recognize bugs Graphics enables animation and plotting Toolkits hide ugly system/language details

Toolkits Promote Economy Encapsulation leads to more economical student programming Toolkits support windows, graphics, IO, and “model classes” (array, queue,...) Toolkits enable programs that “should be” simple to be built in a simple manner

Toolkits and Pedgogy Toolkits provide “objects that matter”, that is, extended examples of functions and classes that do important work Toolkits are a means of teaching design by example Moral: Do not accept the raw machine or the raw language as it is. Build in software the “machine” you would like to work with.

IO Tools Robust, error-checked IO Automatic arithmetic expression evaluation Integration of IO with control flow via the three fundamental IO models: –Mandatory model –Respond-or-default model –Respond-or-decline model

Window Tools Console window Multiple graphics windows Automatic window refresh as needed Acts in the same manner under Windows 98 and Windows NT despite differences in the behavior of the native API’s

Graphics Tools Fully object-oriented foundation Geometric classes in both short and double precision coordinates Lines, rectangles, ovals, polygons, colors, text in the graphics windows Widget classes allow geometric entities to affect the screen and set persistent state

The Array Class The Array class is a model class illustrating –Templates –Dynamic allocation and automatic growth –Distinct notions of total size and valid size –Error checked operator[] access to array cells –Append and Remove at the array end Array class generalizes to Stack and Queue

On To Demos...

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