Instantiating objects

Because of the way PowerBuilder object classes and instances are named, it is easy to think they are the same thing. For example, when you define a window in the Window painter, you are defining an object class.

When you open a window with the simplest format of the Open function, you are instantiating an object instance. Both the class definition and the instance have the same name. In your application, w_main is a global variable of type w_main:

Open(w_main)

When you open a window this way, you can only open one instance of the object.

If you want to open more than one instance of a window class, you need to define a variable to hold each object reference:

w_main w_1, w_2
Open(w_1)
Open(w_2)

You can also open windows by specifying the class in the Open function:

window w_1, w_2
Open(w_1, "w_main")
Open(w_2, "w_main")

For class user objects, you always define a variable to hold the object reference and then instantiate the object with the CREATE statement:

uo_emp_data uo_1, uo_2
uo_1 = CREATE uo_emp_data
uo_2 = CREATE uo_emp_data

You can have more than one reference to an object. You might assign an object reference to a variable of the appropriate type, or you might pass an object reference to another object so that it can change or get information from the object.