Smalltalk is a pure object environment and programming language.
Smalltalk is the oldest mature pure object-oriented language. It is brilliant, simple, and has only a few keywords. It is similar to Tcl in that the control structures are not part of the language.
Almost all good things known in currently-hyped languages come from Smalltalk. For example:
Also many popular program-techniques were developed under Smalltalk first:
Smalltalk also has well-designed standard libraries (Collections, Process Control, I/O).
TpP: My first OO languge was Smalltalk. Squeak is a popular Smalltalk implementation with an active community, and several interesting features. If you want to play with Smalltalk, Squeak is a good start.
Why is Smalltalk not the most most popular object-oriented programmming language? The reasons could be:
RLH: Deployment is a lot better in Smalltalk (though still a little clunky). Here [L1 ] is a little walkthough on how a developer decided between C++ and Smalltalk.
Talking of syntax, here's a snippet from [L2 ] - double-quoted strings are just comments:
7 "a number" $z "a character" 'colourless ideas sleep furiously' "a string" #(#tom #dick #harry) "an array of 3 components" #(# one 'should shower at least' 3 'times a week')
# before a string turns it into a symbol (like quote in LISP); #(...) denotes what we'd call a list.
RS can't help finding Tcl simpler, and better-looking...
Lars H: Does # work like / in Postscript? In that language, /tom is just a name whereas tom is a command. Anyhow I agree Tcl looks better.
RS: Yes, #tom is the symbol tom, 'tom' is a string constant, and tom either variable or method/keyword.
Let see some sample program to show all main Smalltalk syntax and look and feel.
| myVar myVar2 | " Variable Definition"
myVar := SampleClass new. "Create Instance of Class Sample Class.
new is simple method call on object SampleClass not special operator
Everything is object"
myVar setSample: 1. "call method setSample: with one parameter"
myVar setSample: 2 with: 3. "call method setSample:with: with two parameters"
"method chaning java myVar.getAnotherObjekt().callThisObjectWith(23)"
myVar getAnotherObjekt callThisObjectWith: 23.
"Now Blocks"
myVar isRead ifTrue: [Transcpript show: 'I am Ready'] ifFalse: [Transcript show: 'Not Ready']
"Or somethig like C operator ? : "
myVar := myVar isRead ifTrue: [1] ifFalse: [2].
"Collection"
myVar := Array new.
"Write Collection on stdout"
myVar do: [:each | Transcript show: each printString].
"Blocks are also objects. That can take parameters. see also Ruby language"
"Blocks can be used do define new control stuctures or something like handlers"
myVar := [:par1 | Transcript show: par1].
"Evalute Block."
myVar value: 2.
"same as"
[:par1 | Transcript show: par1] value: 2
"method cascading"
myVar method1; method2; method3
"equal to"
myVar method1. myVar method2. myVar method3Yes. It looks strange. It is not like Fortran, C, C++, Java or C#. It is also not like basic, perl, bash, tcl....
Shin The Gin 2007-01-4: If you are addicted to the convenience of a common Smalltalk environment, give Tcltalk a try! You'll find workspaces and browsers and even logging of changes, all without object orientation.
RS: Could one say that Smalltalk's "blocks with parameters" correspond to Tcl's upcoming apply lambdas (starting from 8.5)?
NEM: Yes and no. As I understand it, Smalltalk blocks are full lexical closures, so they are a bit more powerful than Tcl's lambdas. Smalltalk is actually quite a nice functional programming language as well as OO.
RJH 2013-05-15:
Forgive my confusion; but the original author appears to claim that 'garbage collection' originated in smalltalk. I was under the impression that smalltalk originated somewhere around the early 1970s and that garbage collection originated with Mr. McCarthy's LISP in the late 1950s...
Have I misunderstood the history - or is the claim that smalltalk originated GC a little overenthusiastic?
Thanks, R.