Squeak Tutorial

Typographical Conventions

To facilitate the use of this document, the following conventions are used:

Code examples are displayed in a typewriter font on a light gray background:

 "the sum of two integer values"
 3 + 4

The result of an evaluation, when it is given at all, is displayed in blue:

 "the sum of two integer values"
 3 + 4
=> 7

Occasionally you will be asked to enter some text. A proposal of input text is displayed on a gray background with a blue border:

PaintWindow

Code is often constructed stepwise and every step is shown as an example. Recently added code is shown in bold, removed text is struck out:

 "first step"
 aView
    addSubView: DiagramDisplayView new

This is modified to become:

 "first step"
  aView
    addSubView: DiagramDisplayView new
    addSubView: DiagramDisplayView new below: headerView

Code fragements are displayed like example code, but additionally a green border is drawn around the example text:

   | topView subView1 subView2 |
   < ... >
  subView1 window: (0 @ 0 extent: 20 @ 100).
  topView addSubView: subView1.
  subView2 window: (0 @ 0 extent: 80 @ 100).
  topView addSubView: subView2
           toRightOf: subView1.

Occasionally, wrong code is discussed. As a general rule, wrong code is written in red:

 "a wrong example"
   [stream atEnd]
       ifTrue: [stream close]

Complete class methods are marked with a blue bar on the left:

instanceFor: anObject
  ^self new owner: anObject

Complete instance methods are marked with a green bar on the left:

printOn: aStream
  aStream nextPutAll: self class name.

Class definitions are marked with an orange bar on the left:

Model subclass: #VariableSubViewExample
      instanceVariableNames: 'switch1 switch2 currentAspect
                              graphicSubmodel textSubmodel'
      classVariableNames: ''
      poolDictionaries: ''
      category: 'MVCTutorial-AdvancedExamples'

An important note is displayed with a red bar on the left of the text:

A note that is emphasized by a red bar on the left should always be carefully read.

Mathematical expressions are displayed on a yellow background with a pale blue border:

             1
a_n  =  1 +  ---
             n

Often, a convention or a requirement is best explained by an assertion, that is, by a logical expression that is required to hold. Assertions are written on a light green background:

elements allSatisfy: [:elem | elem isKindOf: Integer]

A class hierarchy is displayed on a pale yellow background. An underlined blue » following a class name depicts a link to a separate page with further information about that class:

Object  »
  Magnitude  »
    Number  »
      Integer
        SmallInteger

The class catalog contains detailed information about the instance variables of many classes. On the class catalog pages, a variable name is written in light blue, its data type in red. The date type is underlined when additional information is available on a separate page.

Here is an example from the description of class View:

subViews - OrderedCollection
A collection of all subviews of the view. This variable is initialized to an empty OrderedCollection, but some instance methods replace this collection with nil.
The following assertion should hold:
```
subViews isNil
    or: [subViews allSatisfy: [:sv | sv superView == self]]
```

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