Smalltalk and Object Orientation: an Introduction - Free

34. Appendix: The Smalltalk Language Syntax
34.1 Basic syntax
34.1.1 Statement separation
Achieved in Smalltalk by the
example:
period or full stop rather than the semi -colon as in Pascal or C. For
Transcript show: 'Hello World'.
Transcript show: ' John'.
Although it is unnecessary to put a period at the end of the last line of code, as in Pascal it is a good
idea.
34.1.2 Assignment operator
The a ssignment operator is the colon equals combination as in other languages such as Pascal. For
example:
a := 2 + 4.
This operator is not a “copy” operator and thus may result in two variables referencing the same
object. Not that := is not a message as var iables are not objects (whereas + is a message as it relates to
two objects even if one is contained within a variable).
Further example are:
oldIndex := 1.
newIndex := oldIndex.
myArray := #(1 2 3 4).
myName := 'John Hunt'.
Assignments return values (like other expressions), so that several assignments can be made together:
34.1.3 Comments
nextIndex := newIndex := oldIndex.
Comments are defined using “ ”. Everything between the double quotes is treated as a comment. Note
that comments cannot be nested in Sma lltalk. This can be awkward if you wish to comment out some
code for later.
34.1.4 The return operator
This operator is used to return a value from a method. By default a method will return the object that the
message which triggers the method was sent to. Howeve r, this can be altered using the return operator
^. For example:
^24
would cause a method to return the value 24. Note that the method will “return” as soon as it encounters
a return operator. It is therefore possible, although not necessarily a good ide a, to have more than one
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