article Free Access Share on Is multiple inheritance essential to OOP? (panel) Authors: Yen-Ping Shan View Profile , Tom Cargill View Profile , Brad Cox View Profile , William Cook View Profile , Mary Loomis View Profile , Alan Snyder View Profile Authors Info & Claims ACM SIGPLAN NoticesVolume 28Issue 10Oct. 1, 1993 pp 360–363https://doi.org/10.1145/167962.165923Published:01 October 1993Publication History 3citation781DownloadsMetricsTotal Citations3Total Downloads781Last 12 Months30Last 6 weeks2 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

We wish to determine the effectiveness of some simple hardware for debugging and profiling compiled programs on a conventional processor. The hardware cost is small -- a counter decremented on each instruction that raises an exception when its value becomes zero. With the counter a debugger can provide data watchpoints and reverse execution: a profiler can measure the total instruction cost of a code segment and sample the program counter accurately. Such a counter has been included on a single-board MC68020 workstation, for which system software is currently being written. We will report our progress at the symposium.

Pi is a debugger written in C + +. This paper explains how object-oriented programming in C + + has influenced Pi's evolution. The motivation for object-oriented programming was to experiment with a browser-like graphical user interface. The first unforeseen benefit was in the symbol table: lazy construction of an abstract syntax-based tree gave a clean interface to the remainder of Pi, with an efficient and robust implementation. Next, though not in the original design, Pi was easily modified to control multiple processes simultaneously. Finally, Pi was extended to control processes executing across multiple heterogeneous target processors.

Abstract joff is an asynchronous, source‐level, break‐and‐examine debugger for C programs running on the Blit, a programmable bitmap terminal, joff is implemented as two processes: a small process running in the terminal and a larger process running in a time‐sharing host. The constraints on its design and a menu‐driven user interface combine to present an unusual set of implementation difficulties. The way the problems were tackled and the degree to which they were solved may be interesting to those designing other debuggers. Operating system designers should assess the merits of a debugger that runs asynchronously with its subject and consider providing the necessary support.

Abstract The rendezvous is an important concept in concurrent programming—two processes need to synchronize, i.e. rendezvous, to exchange information. The Ada programming language is the first programming language to use the rendezvous as the basis of its concurrent programming facilities. Our experience with rendezvous facilities in the Ada language shows that these facilities lead to and encourage the design of programs that poll. Polling is generally, but not always, undesirable because it is wasteful of system resources. We illustrate and examine the reasons for polling bias in the Ada language. We give suggestions on how to avoid polling programs, and suggest changes to the rendezvous facilities to eliminate the polling bias. The ramifications of these changes to the implementation of the Ada language are also discussed. Although we have focused on the rendezvous facilities in the Ada language our analysis is also applicable to other languages. A polling bias can occur in any concurrent programming language based on the rendezvous mechanism if it does not provide appropriate facilities.

Abstract A distributed solution to Dijkstra's ‘Dining Philosophers’ problem is presented. There is no central synchronization mechanism and it is robust in that the impact of failures is local. The solution is amenable to implementation using a wide class of synchronization primitives. A concrete implementation is presented in Ada.

Abstract This paper describes a simple full‐screen editor which operates effectively in a very restrictive hardware and software environment in which dumb CRT terminals run half‐duplex at 1200 baud to the line buffering front‐end of a timesharing mainframe. The use of such an inappropriate system is dictated by other considerations and the experiment with screen editing was motivated by the frustration encountered in manipulating highly formatted text with a line‐oriented text editor. Early success with a crude editor lead to an improved version which functions acceptably for a several types of text. The particular constraints of this environment, how they were overcome or avoided and their influence on the editor are addressed. The paper demonstrates that successful full‐screen editing in this environment calls for software that differs in its basic design from other full‐screen editors.