Implementing signatures for C++

ABSTRACT

We outline the design and detail the implementation of a language extension for abstracting types and for decoupling subtyping and inheritance in C++. This extension gives the user more of the flexibility of dynamic typing while retaining the efficiency and security of static typing. After a brief discussion of syntax and semantics of this language extension and examples of its use, we present and analyze three different implementation techniques: a preprocessor to a C++ compiler, an implementation in the front end of a C++ compiler, and a low-level implementation with back-end support. We follow with an analysis of the performance of the three implementation techniques and show that our extension actually allows subtype polymorphism to be implemented more efficiently than with virtual functions. We conclude with a discussion of the lessons we learned for future programming language design.

REFERENCES

• 1: Martín Abadi , Luca Cardelli, On subtyping and matching, ACM Transactions on Programming Languages and Systems (TOPLAS), v.18 n.4, p.401-423, July 1996 [doi>10.1145/233561.233563]
• 2: Roberto M. Amadio , Luca Cardelli, Subtyping recursive types, ACM Transactions on Programming Languages and Systems (TOPLAS), v.15 n.4, p.575-631, Sept. 1993 [doi>10.1145/155183.155231]
• 3: Pierre America , Frank van der Linden, A parallel object-oriented language with inheritance and subtyping, ACM SIGPLAN Notices, v.25 n.10, p.161-168, Oct. 1990
• 4: BAUMGARTNER~ G. 1995. Type abstraction using signatures. In Using and Porting GNU CC, R. M. StMlman, Ed. Free Software Foundation, Cambridge, Mass, Section 7.6, 180-182. Available as part of the GCC-2.7.2 distribution.
• 5: Gerald Baumgartner , Vincent F. Russo, Signatures: a language extension for improving type abstraction and subtype polymorphism in C++, Software—Practice & Experience, v.25 n.8, p.863-889, Aug. 1995 [doi>10.1002/spe.4380250803]
• 6: Andrew Black , Norman Hutchinson , Eric Jul , Henry Levy, Object structure in the Emerald system, Conference proceedings on Object-oriented programming systems, languages and applications, p.78-86, September 29-October 02, 1986, Portland, Oregon, United States
• 7: BRUCE, K. B. 1997. Typing in object-oriented languages: Achieving expressibility and safety. A CM Comput. Surv. To be published.
• 8: Luca Cardelli, A semantics of multiple inheritance., Proc. of the international symposium on Semantics of data types, p.51-67, July 1984, Sophia-Antipolis, France
• 9: Luca Cardelli , James Donahue , Lucille Glassman , Mick Jordan , Bill Kalsow , Greg Nelson, Modula-3 language definition, ACM SIGPLAN Notices, v.27 n.8, p.15-42, Aug. 1992 [doi>10.1145/142137.142141]
• 10: William R. Cook , Walter Hill , Peter S. Canning, Inheritance is not subtyping, Proceedings of the 17th ACM SIGPLAN-SIGACT symposium on Principles of programming languages, p.125-135, December 1989, San Francisco, California, United States [doi>10.1145/96709.96721]
• 11: James Donahue , Alan Demers, Data types are values, ACM Transactions on Programming Languages and Systems (TOPLAS), v.7 n.3, p.426-445, July 1985 [doi>10.1145/3916.3987]
• 12: Margaret A. Ellis , Bjarne Stroustrup, The annotated C++ reference manual, Addison-Wesley Longman Publishing Co., Inc., Boston, MA, 1990
• 13: James Gosling , Bill Joy , Guy L. Steele, The Java Language Specification, Addison-Wesley Longman Publishing Co., Inc., Boston, MA, 1996
• 14: GRANSTON~ E. D. AND RUSSO~ V. F. 1991. Signature-based polymorphism for C~~. In Proceedings of the 1991 USENIX C~~ Conference. USENIX Assoc., Berkeley, Calif., 65-79.
• 15: Paul Hudak , Simon Peyton Jones , Philip Wadler , Brian Boutel , Jon Fairbairn , Joseph Fasel , María M. Guzmán , Kevin Hammond , John Hughes , Thomas Johnsson , Dick Kieburtz , Rishiyur Nikhil , Will Partain , John Peterson, Report on the programming language Haskell: a non-strict, purely functional language version 1.2, ACM SIGPLAN Notices, v.27 n.5, p.1-164, May 1992 [doi>10.1145/130697.130699]
• 16: Richard D. Jenks , Robert Sutor, AXIOM: the scientific computation system, Springer-Verlag New York, Inc., New York, NY, 1992
• 17: MAcQUEEN, D. B. 1985. Modules for Standard ML. Polymorphism 2, 2 (Oct.), PAGES.
• 18: David MacQueen, An implementation of standard ML modules, Proceedings of the 1988 ACM conference on LISP and functional programming, p.212-223, July 25-27, 1988, Snowbird, Utah, United States [doi>10.1145/62678.62704]
• 19: Object Management Group 1995. The Common Object Request Broker: Architecture and SpecificationDOT, Rev. 2.0ED ed. Object Management Group, Framingham, Mass.
• 20: Craig Schaffert , Topher Cooper , Bruce Bullis , Mike Kilian , Carrie Wilpolt, An introduction to Trellis/Owl, Conference proceedings on Object-oriented programming systems, languages and applications, p.9-16, September 29-October 02, 1986, Portland, Oregon, United States
• 21: Alan Snyder, Encapsulation and inheritance in object-oriented programming languages, Conference proceedings on Object-oriented programming systems, languages and applications, p.38-45, September 29-October 02, 1986, Portland, Oregon, United States
• 22: CORPORATE SPARC International, Inc., The SPARC architecture manual: version 8, Prentice-Hall, Inc., Upper Saddle River, NJ, 1992
• 23: STALLMAN, R. M. 1995. Using and Porting GNU CC. Free Software Foundation, Cambridge, Mass. Available as part of the GCC-2.7.2 distribution.
• 24: R. S. Sutor , R. D. Jenks, The type inference and coercion facilities in the scratchpad II interpreter, Papers of the Symposium on Interpreters and interpretive techniques, p.56-63, June 24-26, 1987, St. Paul, Minnesota, United States
• 25: S. M. Watt , R. D. Jenks , R. S. Sutor , B. M. Trager, The scratchpad II type system domains and subdomains, Computing tools for scientific problem solving, Academic Press, Inc., Duluth, MN, 1990
• 26: Niklaus Wirth, Programming in MODULA-2 (3rd corrected ed.), Springer-Verlag New York, Inc., New York, NY, 1985

INDEX TERMS

Primary Classification:
  D. Software
  D.3 PROGRAMMING LANGUAGES
      D.3.3 Language Constructs and Features
          Subjects: Abstract data types

Additional Classification:
  D. Software
  D.1 PROGRAMMING TECHNIQUES
  D.2 SOFTWARE ENGINEERING
      D.2.2 Design Tools and Techniques
          Subjects: Modules and interfaces
  D.3 PROGRAMMING LANGUAGES
      D.3.2 Language Classifications

          Nouns: C++
      D.3.4 Processors
          Subjects: Compilers

General Terms:
Design, Languages, Measurement, Performance

Keywords:
C++, dispatch tables, inheritance, opject interfaces, polymorphism, subtyping