Declaring instances of windows

Because a window is actually a datatype, you can declare variables of that datatype, just as you can declare integers, strings, and so on. You can then refer to those variables in code.

For example:

w_employee mywin

declares a variable named mywin of type w_employee.

Limitation of using variables

When you declare a window instance, you cannot reference it from another window. For example, if there are three windows open, you cannot explicitly refer to the first one from the second or third. There is no global handle for windows opened using reference variables. To maintain references to window instances using a script, see Using window arrays.

Opening an instance

To open a window instance, you refer to the window variable in the Open function:

w_employee mywin

Here the Open function determines that the datatype of the variable mywin is w_employee. It then creates an instance of w_employee and assigns a reference to the mywin variable.

If you code the above script for the Clicked event for a CommandButton, each time the button is clicked, a new instance of w_employee is created. In other words, a new window is opened each time the button is clicked.

By creating variables whose datatype is the name of a window, you can open multiple instances of a window. This is easy and straightforward. PowerBuilder manages the windows for you for example, freeing memory when you close the windows.

Closing an instance

A common way to close the instances of a window is to put a CommandButton in the window with this script for the Clicked event:


This script closes the parent of the button (the window in which the button displays). Continuing the example above, if you put a CommandButton in w_employee, the script closes the current instance of w_employee. If you click the CommandButton in the mywin instance of w_employee, mywin closes.