Smalltalk and Object Orientation: an Introduction - Free

Table 24.2: Class message categories
Protocol
instance creation
class initialization
examples
private
Use
Used for methods associated with creating instances
Methods which initialize class variables
Methods which illustrate some use of the class, e.g. instance
creation
Methods that provide support for one of the above
Table 24.2 illustrates the common class message protocols and what they are used for. Table 24.3
does the same thing for the instance message protocols. Notice the practice of naming instance message
protocols as actions. These actions are intended to indicate the type of activity being performed. A n
exception to this is the initialize (or its variant initialize -release) protocol. Although this does not
conform to the standard it is consistent throughout the VisualWorks image and you are therefore
advised to comply with this exception.
Table 24.3: Instance message categories
Category
accessing
adding
converting
comparing
displaying
initialize
printing
updating
Use
Methods used for accessing and updating instance variables.
Used in collection classes for methods which add elements to the
collection.
Holds methods which convert one instance into another instance.
Groups methods used for comparison tests.
Holds methods which relate to displaying information graphically
Holds methods which initialize the instance.
Methods associated with printing the instance such as printString
Used to hold methods which cause some change in the instances
state.
24.6 Further reading
There are a number of places which can provide very useful further reading, f or example [Skublics et al
1996] is an excellent little book which really does provide pearls of wisdom on good Smalltalk style. It
is a book to be dipped into, rather than read from cover to cover. However, if you do manage to
inwardly digest this book, you will be able to write clear, concise, reusable Smalltalk. In addition many
of the core system classes also provide excellent examples of the good Smalltalk style.
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