To use or set a variable’s value in a PowerBuilder script, you name the variable. The variable must be known to the compiler—in other words, it must be in scope.
You can use a variable anywhere you need its value—for example, as a function argument or in an assignment statement.
When PowerBuilder executes a script and finds an unqualified reference to a variable, it searches for the variable in the following order:
A local variable
A shared variable
A global variable
An instance variable
As soon as PowerBuilder finds a variable with the specified name, it uses the variable’s value.
To refer to a global variable, you specify its name in a script. However, if the global variable has the same name as a local or shared variable, the local or shared variable will be found first.
To refer to a global variable that is masked by a local or shared variable of the same name, use the global scope operator (::) before the name:
::globalname
For example, this statement compares the value of local and global variables, both named total:
IF total < ::total THEN ...
You can refer to an instance variable in a script if there is an instance of the object open in the application. Depending on the situation, you might need to qualify the name of the instance variable with the name of the object defining it.
Using unqualified names You can refer to instance variables without qualifying them with the object name in the following cases:
For application-level variables, in scripts for the application object
For window-level variables, in scripts for the window itself and in scripts for controls in that window
For user-object-level variables, in scripts for the user object itself and in scripts for controls in that user object
For menu-level variables, in scripts for a menu object, either the highest-level menu or scripts for the menu objects included as items on the menu
For example, if w_emp has an instance variable EmpID, then you can reference EmpID without qualification in any script for w_emp or its controls as follows:
sle_id.Text = EmpID
Using qualified names In all other cases, you need to qualify the name of the instance variable with the name of the object using dot notation:
object.instancevariable
This requirement applies only to Public instance variables. You cannot reference Private instance variables outside the object at all, qualified or not.
For example, to refer to the w_emp instance variable EmpID from a script outside the window, you need to qualify the variable with the window name:
sle_ID.Text = w_emp.EmpID
There is another situation in which references must be qualified. Suppose that w_emp has an instance variable EmpID and that in w_emp there is a CommandButton that declares a local variable EmpID in its Clicked script. In that script, you must qualify all references to the instance variable:
Parent.EmpID
To avoid ambiguity when referring to variables, you might decide to always use qualified names for object variables. Qualified names leave no doubt about whether a variable is local, instance, or shared.
To write generic code but still use qualified names, you can use the pronouns This and Parent to refer to objects. Pronouns keep a script general by allowing you to refer to the object without naming it specifically.
Window variables in window scripts In a window script, use the pronoun This to qualify the name of a window instance variable. For example, if a window has an instance variable called index, then the following statements are equivalent in a script for that window, as long as there is no local or global variable named index:
index = 5
This.index = 5
Window variables in control scripts In a script for a control in a window, use the pronoun Parent to qualify the name of a window instance variable—the window is the parent of the control. In this example, the two statements are equivalent in a script for a control in that window, as long as there is no local or global variable named “index”:
index = 5
Parent.index = 5
Naming errors If a local or global variable exists with the name “index,” then the unqualified name refers to the local or global variable. It is a programming error if you meant to refer to the object variable. You get an informational message from the compiler if you use the same name for instance and global variables.
