Smalltalk and Object Orientation: an Introduction - Free

eturn operator in a method. Thus allowing a method to return from different points depending on the
execution path taken through the method.
34.1.5 Cascading
The cascade operator, represented by a comma ( , ) can be used to send a series of messages to the same
object (which is only referenced once). For example:
Can be re-written as:
Transcript cr.
Transcript show: 'John Hunt'.
Transcript: tab.
Transcript show: '1995'.
Transcript cr.
Transcript cr;
show: 'John Hunt';
tab;
show: '1995';
cr.
34.2 Literals and variables
34.2.1 Literals
Literals are constant objects such as numbers, characters, strings, symbols etc.
Numbers are a sequence of numeric characters with an optional decimal point and an optional minus
sing. Example of numbers are:
8 12.7 -44.7 0.0009
In Smalltalk a number is positive unless otherwise stated. there is therefore no need for a unary
plus sign. Numbers can also be represented in other bases, by preceding them with a radix and
the letter “r”:
6r145
8r5E
Characters are individual letters and are distinctly different to a string containing only a single letter.
They are represented by a single character preceded by a “$” symbol. For example:
$a $d $’ $+ $4
Strings are collections of characters encompassed within single quotes. They can possess spaces, under
bars etc. For example:
'Hello World'
Symbols are special objects that represent unique entities in the Smalltalk system. These are
represented using a leading the hash (#) symbol.
#temp
#john
34.2.2 Variables
Variable names describe accessible variables. Variable names are identifiers made up of letters and
digits with an initial letter:
someObject MyCar totalNumber
285