Finding functions – PB Docs 126

Unqualified function names

If you do not qualify a function name with an object, PowerBuilder
searches for the function and executes the first one it finds that
matches the name and arguments. It searches for a match in the following
order:

1. A global external function.

2. A global function.

3. An object function and local external function.
   If the object is a descendant, PowerBuilder searches upward through
   the ancestor hierarchy to find a match for the function prototype.

4. A system function.

DataWindow expression functions

The functions that you use in the DataWindow painter in expressions
for computed fields, filters, validation rules, and graphed data
cannot be overridden. For example, if you create a global function
called Today, it is used instead of the PowerScript
system function Today, but it is not used
instead of the DataWindow expression function Today.

Qualified function names

You can qualify an object function using dot notation to ensure
that the object function is found, not a global function of the
same name. With a qualified name, the search for a matching function
involves the ancestor hierarchy only (item 3 in the search list
above), as shown in the following examples of function calls:

When PowerBuilder searches the ancestor hierarchy for a function,
you can specify that you want to call an ancestor function instead
of a matching descendent function.

For the syntax for calling ancestor functions,
see “Calling functions and events
in an object’s ancestor”.