Design Pattern: Application Variables

Smalltalk application designed called for ~10 independent subsystems
Needed to be started/stopped/sent messages
Used Application variables (see IBM Smalltalk: User's Guide: Namespace support)

Declaring application variables

{application} class >> _Pragma_{application}Globals
	"%%PRAGMA DECLARE
		(name: AppVariable1 
			isPool: false 
			isConstant: false 
			valueExpression: 'nil')
		(name: AppVariable2 
			isPool: false 
			isConstant: false 
			valueExpression: 'nil')
	"

Defining application variables

{application} class >> loaded
	AppVariable1 := AppVariable1Class new.
	AppVariable2 := AppVariable1Class new.

Using application variables
- Make sure application variable is used in prereq's application variable is declared/defined in.
- Use the variable like any other global variable

Removing application variables

{application} class >> removing
	AppVariable1 shuttingDown.
	AppVariable1 := nil.