UBC Theses and Dissertations
Presentation techniques for more expressive programs Eisenberg, Andrew David
We introduce a class of program editors that present a program using a rich set of transformations; we call these kinds of editors composable presentation editors. Proper use of these kinds of editors appears to lead to more expressive programs-programs whose structure are aligned with the problem they are trying to solve. By default, the composable presentation editor presents program elements textually as concrete syntax and enables typical editor commands on the program. Metadata on program elements control how the transformations are applied. Customized metadata can re-order, pictorialize, collapse, duplicate, or expand the displayed form of program elements and can additionally alter the available editor commands. We have developed a set of presentation techniques to be used by presentation designers (i.e., the programmers who design how a program is presented in the editor. These techniques relate to well-understood programming language design, editor design, and programming best-practices techniques including scoping, higher order functions, refactoring, prettyprinting, naming conventions, syntax highlighting, and text hovers. We introduce two implementations of composable presentation editors and a number of examples showing how programs can be made more expressive when presentation techniques are properly used. The first implementation is the ETMOP, an open editor, where a metaobject protocol is provided that allows language and editor designers to customize the way program elements are displayed. These customizations are called presenta- tion extensions and the corresponding presentation extension protocol acts in a way similar to the way that syntax macros extend the syntax of a language. The second implementation is Embedded CAL, a closed editor that uses these presentation techniques to embed one language (CAL) inside a host language (Java) through the use of presentation techniques, without changing the syntax or compiler of either language.
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