smalltalk

1 definition found

smalltalk - Free On-line Dictionary of Computing (26 May 2007) :

  Smalltalk
  
     <language> The pioneering object-oriented programming system
     developed in 1972 by the Software Concepts Group, led by Alan Kay
     , at Xerox PARC between 1971 and 1983.  It includes a
     language, a programming environment, and an extensive object
     library.
  
     Smalltalk took the concepts of class and message from
     Simula-67 and made them all-pervasive.  Innovations included
     the bitmap display, windowing system, and use of a mouse.
  
     The syntax is very simple.  The fundamental construction is
     to send a message to an object:
  
     	object message
  
     or with extra parameters
  
     	object message: param1 secondArg: param2 .. nthArg: paramN
  
     where "secondArg:" etc. are considered to be part of the
     message name.
  
     Five pseudo-variables are defined: "self", "super", "nil",
     "true", "false".  "self" is the receiver of the current
     message.  "super" is used to delegate processing of a message
     to the superclass of the receiver.  "nil" is a reference to
     "nothing" (an instance of UndefinedObject).  All variables
     initially contain a reference to nil.  "true" and "false" are
     Booleans.
  
     In Smalltalk, any message can be sent to any object.  The
     recipient object itself decides (based on the message name,
     also called the "message selector") how to respond to the
     message.  Because of that, the multiple inheritance system
     included in the early versions of Smalltalk-80 appeared to be
     unused in practice.  All modern implementations have single
     inheritance, so each class can have at most one superclass.
  
     Early implementations were interpreted but all modern ones
     use dynamic translation (JIT).
  
     Early versions were Smalltalk-72, Smalltalk-74, Smalltalk-76
     (inheritance taken from Simula, and concurrency), and
     Smalltalk-78, Smalltalk-80.  Other versions include Little Smalltalk
     , Smalltalk/V, Kamin's interpreters.  Current
     versions are VisualWorks, Squeak, VisualAge, Dolphin Smalltalk
     , Object Studio, GNU Smalltalk.
  
     See also: International Smalltalk Association.
  
     UIUC Smalltalk archive (http://st-www.cs.uiuc.edu/).
     FAQ (http://XCF.Berkeley.EDU/pub/misc/smalltalk/FAQ/).
  
     Usenet newsgroup: news:comp.lang.smalltalk.
  
     ["The Smalltalk-76 Programming System Design and
     Implementation", D.H. Ingalls, 5th POPL, ACM 1978, pp. 9-16].
  
     (2001-09-11)