When you declare a variable whose datatype is a kind of object, such as a window, you can use the variable to reference any entity defined in the object, but not in one of its descendants. Consider the following code:
w_customer mycust Open(mycust) // The following statement is legal if // w_customer window has a st_name control. mycust.st_name.text = "Joe"
mycust is declared as a variable of type w_customer (mycust is a w_customer window). If w_customer contains a StaticText control named st_name, then the last statement shown above is legal.
However, consider the following case:
window newwin string winname = "w_customer" Open(newwin, winname) // Illegal because objects of type Window // do not have a StaticText control st_name newwin.st_name.text = "Joe"
Here, newwin is defined as a variable of type window. PowerBuilder rejects the above code because the compiler uses what is called strong type checking: the PowerBuilder compiler does not allow you to reference any entity for an object that is not explicitly part of the variable’s compile-time datatype.
Because objects of type window do not contain a st_name control, the statement is not allowed. You would need to do one of the following:
Change the declaration of newwin to be a w_customer (or an ancestor window that also contains a st_name control), such as:
w_customer newwin string winname = "w_customer" Open(newwin, winname) // Legal now newwin.st_name.text = "Joe"
Define another variable, of type w_customer, and assign it to newwin, such as:
window newwin w_customer custwin string winname = "w_customer" Open(newwin, winname) custwin = newwin // Legal now custwin.st_name.text = "Joe"
