Flavors (programming language)
Flavors,[1] an early object-oriented extension to Lisp developed by Howard Cannon at the MIT Artificial Intelligence Laboratory for the Lisp machine and its programming language Lisp Machine Lisp, was the first programming language to include mixins.[2] Symbolics used it for its Lisp machines, and eventually developed it into New Flavors; both the original and new Flavors were message passing OO models. It was hugely influential in the development of the Common Lisp Object System (CLOS).[3]
Implementations of Flavors are also available for Common Lisp.[4]
New Flavors replaced message sending with calling generic functions.
Flavors offers :before and :after daemons with the default method combination (called :daemon).
Flavors and CLOS features comparison
Flavors offers a few features not found in CLOS:
- Wrappers
- Automatic lexical access to slots using variables within methods.
- Internal flavor functions, macros and substs.
- Automatically generated constructors.
DEFFLAVORoptions::required-methods,:abstract-flavor,:mixture.SENDfunction for sending messages.
CLOS offers the following features not found in Flavors:
- Multimethods
- Methods specialized on individual objects (via
EQL). - Methods specialized on Common Lisp types (symbol, integer, ...).
- Methods specialized on def-struct types.
- Class slots.
Terminology
| Flavors | CLOS |
|---|---|
| flavor | class |
| component flavor | superclass |
| dependent flavor | subclass |
| local component flavor | direct superclass |
| local dependent flavor | direct subclass |
| generic function | generic function |
| combined method | effective method |
| method option | method qualifier |
| instance | instance |
| instance variable | slot |
| ordering of flavor components | class precedence list |
References
- Howard Cannon, Flavors: A non-hierarchical approach to object-oriented programming, Symbolics Inc., 1982
- pg 46 of Thompson, C. W., Ross, K. M., Tennant, H. R., and Saenz, R. M. 1983. "Building Usable Menu-Based Natural Language Interfaces To Databases". In Proceedings of the 9th international Conference on Very Large Data Bases (October 31 – November 2, 1983). M. Schkolnick and C. Thanos, Eds. Very Large Data Bases. Morgan Kaufmann Publishers, San Francisco, CA, 43–55.
- "Symbolics (1985) was using New Flavors (a message-sending model, like Java today), Xerox was using CommonLoops, Lisp Machine Incorporated was using Object Lisp (Bobrow, 1986), and Hewlett-Packard proposed using Common Objects (Kempf, 1987). The groups vied with each other in the context of the standardization effort going on for Common Lisp at the time and finally settled on a standard based on CommonLoops and New Flavors." p. 108 of Veitch 1998.
- Flavors for Allegro CL
- Veitch, Jim (1998). "A History and Description of CLOS". In Salus, Peter H. (ed.). Handbook of Programming Languages, Volume IV: Functional and Logic Programming Languages (1st ed.). Macmillan Technical Publishing. pp. 107–158. ISBN 1-57870-011-6.
Further reading
- Moon, David A. (June 1986). "Object-Oriented Programming with Flavors" (PDF). Conference proceedings on Object-oriented Programming Systems Languages and Applications. OOPSLA '86. pp. 1–8. doi:10.1145/28697.28698. ISBN 978-0-89791-204-4. S2CID 17150741. Retrieved March 17, 2022.
- "Flavors, Technical Report", MIT Artificial Intelligence Laboratory, Cambridge (Mass.), 1980
- Daniel Weinreb and David A. Moon, "Flavors: Message Passing in the Lisp Machine", A.I. Memo No. 602, November 1980, MIT AI Lab
