A property typically defines and implements a GET and/or SET accessor, which provides a class object instance with read and write access to the property's data value, respectively. However, a property can define a GET and/or SET accessor without an implementation. In this case, the accessor reads the value from or writes the value to the property’s default memory (that is, a default storage area that holds the property’s current value). At the very least, a property must define either a GET accessor or a SET accessor in order to read or write the property’s value.
If the property defines and implements a GET or SET accessor, the accessor implementation executes implicitly. When you step into code that reads or writes a property’s value, the Debugger steps into the ABL code of that accessor implementation.
In certain cases, the code structure is such that errors occur when the GET accessor implementation executes. This happens, for example, if the implementation uses a buffer handle, and the Debugger executes the accessor before the handle is assigned. To prevent this problem, you can disable the evaluation by the Debugger of properties that have non-empty accessor methods. To do so, start the OpenEdge Client session with the -noevalprops startup parameter. For more information, see OpenEdge Deployment: Startup Command and Parameter Reference.
Consider the following Debugger behavior when examining and editing property values:
If the property only defines a GET or SET accessor, and does not provide an implementation for the accessor, the Debugger reads the value from or writes the value to the property’s default memory.
If the property does not define a GET accessor, the Debugger cannot read the property’s value and displays "** Unavailable **" in the property’s Value cell.
If the property does not define a SET accessor, the Debugger cannot write the property’s value (the Value cell is read-only).
If the property defines only a SET accessor, and no GET accessor, the Debugger can write the property’s value but will immediately display "** Unavailable **" in the property’s Value cell.
If you started the OpenEdge session with the -noevalprops startup parameter, the Value cell displays "** Property evaluation disabled **" for those properties that have a GET method with an implementation. In this case, you can inspect the value of a property in the Dataview dialog box (see Dataviewdialog box.) Note that ABL properties with empty GET methods are always evaluated.
Note: If a property defines and implements a GET or SET accessor, the value of the property can change each time the Debugger reads or writes the property because the accessor implementation will execute each time, and its logic might change the property’s value. For example, a property’s GET accessor might calculate the property’s value based on the current time.
If the property only defines a GET or SET accessor, and does not provide an implementation for the accessor, the Debugger reads the value from or writes the value to the property’s default memory.