Defining the class TextEditor

Next, create a subclass of Object:

1.	From the Classes menu, select Add > Subclass.

2.	When a prompter opens, enter the name of your new class, for example, TextEditor.

3.	In the next prompter, select subclass; then select OK.

4.	In the description pane, which now displays the description for TextEditor, do the following:

a.	Add the instance variables mainWindow menuBar workRegion shell text fileName modified popup.

b.	Add the pool dictionaries CfsConstants CldtConstants CgConstants CwConstants.

5.	Save the class.

Implementing the public instance methods

TextEditor has six public instance methods: cr (carriage return), display, nextPutAll:, open, openOn:, and show:. You can implement them in any order.

Public methods for the category Initialization & Startup

Method open

open

"Public - Creates and realizes the receiver."

self

createShell;

createWindow.

mainWindow

setAreas: menuBar

horizontalScrollbar: nil

verticalScrollbar: nil

workRegion: workRegion;

manageChild.

self realizeWindow.

Method openOn:

openOn: pathName

"Public - Opens the receiver on the text file specified by pathName."

self open.

self

fileName: pathName;

undo: nil clientData: nil callData: nil.

Public methods for category File Operations

Method cr

cr

"Public - Inserts a carriage return."

self nextPutAll: (String with: Lf)

Method display

display

"Public - Displays the shell."

^self shell display.

Method nextPutAll:

nextPutAll: aString

"Public - Appends the contents of aString to the receiver."

| pos |

text insert: (pos := text getLastPosition) value: aString;

showPosition: pos + aString size.

text updateWidget.

Method show:

show: aString

"Public - Appends the contents of aString to the receiver."

self nextPutAll: aString.