Smalltalk 音标拼音: [sm'ɔlt
, ɔk]
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 )
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