Flavors is 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. It is notable as the first programming language to include mixins. 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).

Implementations of Flavors are also available for Common Lisp.

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.
  • DEFFLAVOR options: :required-methods, :abstract-flavor, :mixture.
  • SEND function 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 terminology
FlavorsCLOS
flavorclass
component flavorsuperclass
dependent flavorsubclass
local component flavordirect superclass
local dependent flavordirect subclass
generic functiongeneric function
combined methodeffective method
method optionmethod qualifier
instanceinstance
instance variableslot
ordering of flavor componentsclass precedence list
  • 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). (PDF). Conference proceedings on Object-oriented Programming Systems Languages and Applications. OOPSLA '86. pp. 1–8. doi:. ISBN 978-0-89791-204-4. S2CID .
  • "Flavors, Technical Report", MIT Artificial Intelligence Laboratory, Cambridge (Mass.), 1980
  • Daniel Weinreb and David A. Moon, , A.I. Memo No. 602, November 1980, MIT AI Lab