THE OBJECT ORIENTED IMPLEMENTATION OF A DOCUMENT EDITOR

Traditional document editors am large and complex. Using first-class objects to represent individual characters in a document, we have implemented an editor that is much smaller and simpler than editors of comparable power. This editor, named "Doc", uses object sharing to reduce memory usage and an incremental update strategy to minimize screen redraw time. Our measurements show the current Doc implementation uses 10 bytes for each character in a document and 30 bytes for each visible character. On a 10-MIPS workstation, Doc can draw over 10 full pages per second and can keep pace with interactive typing speeds. These measurements and our experience using Doc shows that a fully object-oriented approach to document editing is practical. We used the editor to prepare and publish this paper.