Progress Class inheriting from DotNet Class has error 12882

If an ABL class inherits from a .NET class and implements an ABL interface, and if the procedure defines a variable as the ABL interface type, instantiates the object, and invokes one of the inherited methods, the invocation fails with error 12882 (Could not access element '' of class '' using object of type '' - compilation is out of date.).

Apr 25, 2017
Knowledge

Title

URL Name

000028005

Article Number

000146836

Environment

Product: OpenEdge Version: 10.2x, OE 11.x Platform: All Windows platforms Other: OO ABL, .NET

Question/Problem Description

An ABL class inherits from a .NET class and implements an ABL interface.
Some of the methods defined in the interface are inherited by the ABL class from the .NET class rather than being directly implemented in the ABL class.
The ABL class compiles with no errors if the .NET class is available in a DLL and referenced properly.
When a procedure defines a variable as the ABL class type, instantiates the object, and invokes one of the inherited .NET methods, the method inherited from the .NET class is run.

However, if the procedure defines a variable as the ABL interface type, instantiates the object, and invokes the same method, the invocation fails with error 12882 (Could not access element '' of class '' using object of type '' - compilation is out of date.).

Steps to Reproduce

Clarifying Information

The attached file 000028005.zip contains everything needed to run the reproducible case, including ClassBug.dll which contains the .NET class. Class1.cs contains the source code for ClassBug.dll.

1. Extract the attached file 000028005.zip into your working directory.
2. prowin32 -p testclassbug.p
3. Three messages will appear; dismiss each one to see the next. The first message simply says "Start". The second message comes from the ABL class instance; the message is displayed by the inherited .NET class. The third message comes from the ABL interface instance; it is the error 12882 message.

Error Message

Could not access element '' of class '' using object of type '' - compilation is out of date. (12882)

Defect Number

Defect PSC00241478 / OE00217521 , PSC00203004 / OE00171291

Enhancement Number

Cause

The interface is an ABL interface but it is implemented by the .NET parent of a hybrid.
Since we are referencing the class member via a reference to the interface, the compiler has no idea (and cannot have any) that this call is meant to go to .NET. So at runtime we try to call the ABL.
This functionality is at this time not supported.

Resolution

None at this time. Until the fix is available, use the workaround below.

Workaround

Use either of the following workarounds depending on application requirements:

1. Define the run-time object as an instance of the ABL class rather than as an instance of the ABL interface.
2. Define the inherited .NET methods as virtual in the .NET class and override them in the derived ABL class. The implementation in the ABL can simply call SUPER:<method>. For example.:

SUPER:FindSameWindowAs().

Notes

Keyword Phrase

Last Modified Date

6/8/2017 2:09 PM

Progress Class inheriting from DotNet Class has error 12882

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