1. DEV-12: What’s New in Object-Oriented ABL
OpenEdge 10.1C and beyond
With 10.1A Progress introduced support for object-oriented programming in the OpenEdge ABL. As part of its continued development 10.1C included additional Object-oriented ABL features that ABL developers have come to expect from a flexible, modern language. This session will describe support for statically defined members of a class, which will allow a class to maintain data, and methods that act on it, for the class as a whole rather than for an individual instance of a class. This now enables native support for a singleton object. It will also introduce features such as syntax to work with classes dynamically and support for character to longchar data widening between methods.
Shelley Chase
OpenEdge Architect

2. Agenda Overview of Object-oriented ABL 10.1C Features Futures
Static behavior and data
Dynamic programming
Error handling
Data widening, NEW function, reserved keywords, THIS-OBJECT
Futures
DEV-12 What’s New in the Object-Oriented ABL

3. What is Object-oriented ABL…
OpenEdge 10.1 Releases
Functionality centered around objects
Classes encapsulate data and behavior
Properties and variables
Methods, constructors and destructor
Inheritance shares common behavior
Interfaces publish a common API
Objects are the runtime instance of a class
Strong-typing does compile time validation
Can be combined with procedures
DEV-12 What’s New in the Object-Oriented ABL

4. Benefits of Procedural and OO Programming
OpenEdge is committed to both programming models
Procedures and Classes
Modular programming
Supports reuse of common behavior (super)
Maps well to OpenEdge Reference Architecture
Classes only
Programming errors caught early by compiler
Natural integration with modeling tools and other Object-oriented platforms like .NET™
Modern programming model (used at most universities)
DEV-12 What’s New in the Object-Oriented ABL

5. Agenda Overview of Object-oriented ABL 10.1C Features Futures
Static behavior and data
Dynamic programming
Error handling
Data widening, NEW function, reserved keywords, THIS-OBJECT
Futures
DEV-12 What’s New in the Object-Oriented ABL

6. Wouldn’t It Be Great If…
Classes supported global variables within a session?
You could always get a reference to the same object every time you wanted to… without keeping track of anything?
… Static Class Members
DEV-12 What’s New in the Object-Oriented ABL

7. A Step Back: Instance Data
Separate copy of data for each instance
Always need to NEW an object to access members
Unique data segment for each instance
MyClass
Data
Data
Data
Data
OpenEdge Runtime
DEV-12 What’s New in the Object-Oriented ABL

8. Instance Data Count = 1 CLASS MyClass:
Name = Joe
CLASS MyClass: …
DEFINE PUBLIC PROPERTY Count AS INT
GET.
SET.
DEFINE PUBLIC PROPERTY Name AS CHARACTER
CONSTRUCTOR MyClass ( inName AS CHARACTER ):
Name = inName.
Count = Count + 1.
END CONSTRUCTOR.
END CLASS.
DEF VAR myClassRef AS CLASS MyClass.
myClassRef = NEW CLASS MyClass( “Joe” ).
DELETE OBJECT myClassRef.
myClassRef = NEW CLASS MyClass( “Tim” ).
myClassRef = NEW CLASS MyClass( “Ann” ).
Count = 1
Name = Tim
Count = 1
Name = Ann
DEV-12 What’s New in the Object-Oriented ABL

9. Classes and Static Data
One copy of data for the session
Access to static members do not require a NEW object
One global data segment
MyClass
Static Data
Static Data
Static Data
Static Data
OpenEdge Runtime
DEV-12 What’s New in the Object-Oriented ABL

10. Static Data Count = 3 Name = Ann Count = 2 Name = Tim Count = 1
Name = Joe
CLASS MyClass: …
DEFINE PUBLIC STATIC PROPERTY Count AS INT
GET.
SET.
DEFINE PUBLIC STATIC PROPERTY Name AS CHARACTER
CONSTRUCTOR MyClass ( inName AS CHARACTER ):
Name = inName.
Count = Count + 1.
END CONSTRUCTOR
END CLASS.
MyClass:Count = MyClass:Count + 1.
MyClass:Name = “Joe”.
MyClass:Name = “Tim”.
MyClass:Name = “Ann”.
DEV-12 What’s New in the Object-Oriented ABL

11. Classes are not Static…
Mix of instance and static members allowed
Static members accessed using class type name
Instance members accessed using object reference
Unqualified references allowed inside class
Static members created before instances
Static constructor runs before instances

12. ABL Static Data – “Typed” Global Data
Definition of static properties and data members
Useful for session-wide data
Variables, buffers, temp-tables, queries, datasets, data sources
Available anywhere in the session
Single instance life-cycle controlled by the AVM
Access using class type name
DEFINE PUBLIC STATIC PROPERTY Count AS INT
GET.
SET.
MESSAGE MyClass:Count.
DEV-12 What’s New in the Object-Oriented ABL

13. ABL Static Constructor
Definition of static constructor
Useful to initialize static data
Only one static constructor per class
No arguments or access mode
Can access STATIC data of the class
Can RUN procedures
Can NEW classes (even this one!)
Run automatically before any class member access is allowed
CONSTRUCTOR STATIC MyClass ( ):
Count = 0. /* Initialize static counter */
END.
DEV-12 What’s New in the Object-Oriented ABL

14. ABL Static Methods Definition of static methods
Useful when instance data is not required
Can access STATIC data of the class
Can RUN procedures
Can NEW classes (even this one!)
Available anywhere in the session
Access using class type name
METHOD STATIC PUBLIC INT DisplayMessage( c AS CHAR ):
MESSAGE c VIEW-AS ALERT-BOX.
END.
MyClass:DisplayMessage( “Statics are cool” ).
DEV-12 What’s New in the Object-Oriented ABL

15. Accessing a Static Class Member
/* MyClass class not instantiated */
MESSAGE MyClass:Count VIEW-AS ALERT-BOX.
Access static data member Count
Runtime checks if static class members are loaded; it’s not so
MyClass
DEV-12 What’s New in the Object-Oriented ABL

16. Accessing a Static Class Member
/* MyClass class not instantiated */
MESSAGE MyClass:Count VIEW-AS ALERT-BOX.
Access static data member Count
Runtime checks if static class members are loaded; it’s not so
Creates static global data segment
ttUsers and Count
MyClass
STATIC
ttUsers
Count
DEV-12 What’s New in the Object-Oriented ABL

17. Accessing a Static Class Member
/* MyClass class not instantiated */
MESSAGE MyClass:Count VIEW-AS ALERT-BOX.
Access static data member Count
Runtime checks if static class members are loaded; it’s not so
Creates static global data segment
ttUsers and Count
Runs static constructor
Initialize Count and ttUsers
MyClass
STATIC
ttUsers = …
Count = 0
Joe, 3
Tim, 2
Ann, 5
DEV-12 What’s New in the Object-Oriented ABL

18. Accessing a Static Class Member
/* MyClass class not instantiated */
MESSAGE MyClass:Count VIEW-AS ALERT-BOX.
Access static data member Count
Runtime checks if static class members are loaded; it’s not so
Creates static global data segment
ttUsers and Count
Runs static constructor
Initialize Count and ttUsers
Gets value of Count
MyClass
STATIC
ttUsers = …
Count = 0
DEV-12 What’s New in the Object-Oriented ABL

19. New’ing a Class with Static Members
DEFINE VAR objRef AS MyClass.
objRef = NEW CLASS MyClass( “Joe” ).
MyClass
NEW an instance of MyClass
Runtime checks if static class members are loaded; it is.
STATIC
ttUsers = …
Count = 0
DEV-12 What’s New in the Object-Oriented ABL

20. New’ing a Class with Static Members
DEFINE VAR objRef AS MyClass.
objRef = NEW CLASS MyClass( “Joe” ).
MyClass
NEW an instance of MyClass
Runtime checks if static class members are loaded; it is.
Creates local data segment
name
STATIC
ttUsers = …
Count = 0
Instance
name
DEV-12 What’s New in the Object-Oriented ABL

21. New’ing a Class with Static Members
DEFINE VAR objRef AS MyClass.
objRef = NEW CLASS MyClass( “Joe” ).
MyClass
NEW an instance of MyClass
Runtime checks if static class members are loaded; it is.
Creates local data segment
name
Runs instance constructor
Sets instance data name
Increments static data Count
STATIC
ttUsers = …
Count = 1
Instance
name = Joe
DEV-12 What’s New in the Object-Oriented ABL

22. New’ing a Class with Static Members
DEFINE VAR objRef AS MyClass.
objRef = NEW CLASS MyClass( “Joe” ).
MyClass
NEW an instance of MyClass
Runtime checks if static class members are loaded; it is.
Creates local data segment
name
Runs instance constructor
Sets instance data name
Increments static data Count
Assigns new instance to object reference
STATIC
ttUsers = …
Count = 1
Instance
name = Joe
DEV-12 What’s New in the Object-Oriented ABL

23. New’ing a Class with Static Members
DEFINE VAR objRef2 AS MyClass.
objRef2 = NEW CLASS MyClass( “Tim” ).
MyClass
NEW an instance of MyClass
Runtime checks if static class members are loaded; it is.
Creates local data segment
name
Runs instance constructor
Sets instance data name
Increments static data Count
Assigns new instance to object reference
STATIC
ttUsers = …
Count = 2
Instance
name = Joe
Instance
name = Tim
DEV-12 What’s New in the Object-Oriented ABL

24. New’ing a Class with Static Members
DEFINE VAR objRef3 AS MyClass.
objRef3 = NEW CLASS MyClass( “Ann” ).
MyClass
NEW an instance of MyClass
Runtime checks if static class members are loaded; it is.
Creates local data segment
name
Runs instance constructor
Sets instance data name
Increments static data Count
Assigns new instance to object reference
STATIC
ttUsers = …
Count = 3
Instance
name = Joe
Instance
name = Tim
Instance
name = Ann
DEV-12 What’s New in the Object-Oriented ABL

25. Singleton Design Pattern
Single instance of the class
Available from anywhere within the session
Loaded on demand
Singleton Class
Instance Data members
Avoids any restrictions on static data
Private or protected constructor
Single instance created on demand
Used to return an object reference to a single instance of the class
DEV-12 What’s New in the Object-Oriented ABL

26. Demo – Singleton Class
DEV-12 What’s New in the Object-Oriented ABL

27. Developing with STATIC Members
Static lifecycle controlled by OpenEdge Runtime
Static class members loaded for the life of the session
When a .cls file is changed and re-compiled, the static portion is NOT refreshed
Caution during development
One active session shared by application and development environment
Recompile does not reload any static changes
Runtime error for mismatches can occur
Session must be restarted
DEV-12 What’s New in the Object-Oriented ABL

28. Developing with STATIC Members
Static lifecycle controlled by OpenEdge Runtime
Static class members loaded for the life of the session
When a .cls file is changed and re-compiled, the static portion is NOT refreshed
Caution during development
One active session shared by application and development environment
Recompile does not reload any static changes
Runtime error for mismatches can occur
Session must be restarted
Use Architect Launch Configurations
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29. Wouldn’t It Be Great If…
You could create an instance of a class passing in a character expression for the class type name at runtime?
… DYNAMIC-NEW and DYNAMIC-CAST
DEV-12 What’s New in the Object-Oriented ABL

30. Dynamic Programming in OO ABL
OO Strong-typing restricts dynamic programming
DYNAMIC-NEW
New a class using a character expression and it’s constructor parameters
Object reference is normally a super class
DYNAMIC-CAST
Cast an object reference to a type using a character expression
Full Progress.Lang.Class reflection API still on roadmap
DEV-12 What’s New in the Object-Oriented ABL

31. Dynamic Object Creation
DYNAMIC-NEW
Used to create a new instance
Fully qualified character type name
USING is not used
Common parameter list
Returns a strongly-typed object
Type checked at runtime
BusinessEntity
BEEmployee
BECustomer
METHOD BusinessEntity CreateBE( beType AS CHAR):
DEFINE VARIABLE myObj AS BusinessEntity.
myObj = DYNAMIC-NEW STRING(“BE” + beType)(parm1, …).
RETURN myObj.
END METHOD.
“BE” + beType
DEV-12 What’s New in the Object-Oriented ABL

32. Dynamic Object Casting
DYNAMIC-CAST
Used to cast an object reference
Fully qualified character type name
USING is not used
Returns a strongly-typed object
Type checked at runtime
BusinessEntity
BEEmployee
BECustomer
METHOD BusinessEntity CreateBE( beType AS CHAR):
DEFINE VARIABLE myObj AS BusinessEntity.
myObj = DYNAMIC-NEW STRING(“BE” + beType)(parm1, …).
DYNAMIC-CAST( myObj,STRING(“BE” + beType).
RETURN myObj.
END METHOD.
“BE” + beType
“BE” + beType
DEV-12 What’s New in the Object-Oriented ABL

33. ClassFactory Design Pattern
Class returns different types of classes
Available from anywhere within the session
Alternative is a large CASE statement
ClassFactory Class
Creates different classes
Common super class for all classes
Common set of constructor parameters
Type name passed in at runtime
DEV-12 What’s New in the Object-Oriented ABL

34. Demo – Class Factory
DEV-12 What’s New in the Object-Oriented ABL

35. Wouldn’t It Be Great If…
ABL had a common way to deal with all errors (system and application)?
An error could be thrown out of the local block / procedure and handled elsewhere?
… Structured Error Handling
DEV-12 What’s New in the Object-Oriented ABL

36. Structured Error Handling
TRY – CATCH model
Based on new built-in error objects
Uses existing ABL blocks: DO, REPEAT, …
System and application errors treated equally
Can be used in classes and procedures
Fully integrated with existing error handling
NO-ERROR
ERROR-STATUS
RETURN ERROR
DEV-12 What’s New in the Object-Oriented ABL

37. Error Object Hierarchy
Progress.Lang.Object
The OO portion of the talk – object hierarchy makes all this possible!
Every object has as its root PLO
Interface (makes it possible to catch errors that are not OpenEdge errors)
(more applicable with .NET)
PLP is the root of built-in error objects
PLE is all system generated errors – errors raised by the AVM, OpenEdge runtime (FIND fails)
PLA is any error your application requires – raised by the programmer
Any error you define!
What does it mean to catch different kinds of errors?
SysError – all system generated errors
AppError – all errors raised by the applications (or distinguish and catch specific user-defined types)
ProError – catches all errors – then CAST to get to specific error info.
interface – catches all errors as well, including third party errors that implement the interface, such as System.Exception
Progress.Lang.
Error
<<interface>>
Progress.Lang.ProError
Application Errors
System Errors
Progress.Lang. AppError
Progress.Lang. SysError
User-Defined
Error Objects
Progress.Lang.
SoapFaultError
DEV-12 What’s New in the Object-Oriented ABL

38. Error Handling Example: System Error
CATCH put on existing FOR EACH block…
FOR EACH Customer:
FIND Order /* Fails */
MESSAGE "Never reach here".
CATCH err AS Progress.Lang.SysError:
/* Handle error here */
MESSAGE err:GetMessage(1).
END CATCH.
END.
DEV-12 What’s New in the Object-Oriented ABL

39. Error Handling Example: Application Error
CATCH put on existing DO block for running a procedure…
DO ON ERROR, UNDO LEAVE:
RUN doIt.p. /* RETURNS AppError */
MESSAGE "Never reach here".
CATCH err AS Progress.Lang.AppError:
/* Handle error here */
MESSAGE err:ReturnValue.
END CATCH.
END.
DEV-12 What’s New in the Object-Oriented ABL

40. Wouldn’t It Be Great If…
CHARACTER data could be passed for a LONGCHAR
NEW could be called as an expression
Reserved keywords could be used for class member names
THIS-OBJECT could be used to qualify a class member
DEV-12 What’s New in the Object-Oriented ABL

41. Data Widening More flexible parameters passing 10.1B New for 10.1C
Strong-typing rules for compatibility
More flexible parameters passing
10.1B
New for 10.1C
Narrower to Wider
INTEGER > INT64 > DECIMAL
DATE > DATETIME > DATETIME-TZ
Narrower(32K) to Wider (1GB)
CHARACTER > LONGCHAR
DEV-12 What’s New in the Object-Oriented ABL

42. NEW function NEW statement ( 10.1A ) NEW function ( 10.1C )
Similar to an assignment
Assigns an object reference to a variable
NEW function ( 10.1C )
Object created as part of an expression
Returns a reference to new object
No need to assign it to an intermediate variable
DEV-12 What’s New in the Object-Oriented ABL

43. Caution Using NEW function
Object cleanup
Object not assigned to anything – memory leak!
Object assigned to something
Parameter receiving object responsible for cleanup
MESSAGE “Using NEW function”
(NEW myObject()):myMethod( ).
RUN myProc.p ( INPUT NEW myObject() ).
DEV-12 What’s New in the Object-Oriented ABL

44. Caution Using NEW function
Object cleanup
Object not assigned to anything – memory leak!
Object assigned to something
Parameter receiving object responsible for cleanup
Garbage Collection planned for 10.2A
MESSAGE “Using NEW function”
(NEW myObject()):myMethod( ).
RUN myProc.p ( INPUT NEW myObject() ).
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45. Reserved Keywords in Classes
ABL Reserved Keywords can be used for:
Class names
Best to prefix with packages
Method names
CLASS Form:
CONSTRUCTOR PUBLIC Form( ): …
METHOD PUBLIC INT Create( ):
DEFINE VAR myClass AS CLASS Form.
myClass = New Form( ).
myClass:Create( ).
DEV-12 What’s New in the Object-Oriented ABL

46. THIS-OBJECT as a Local Qualifier
Qualifier used inside a class when accessing local method, variable, and property names
Identifies member as class instance
Enables content assist in Architect
Required when a local method name is a reserved keyword
CLASS Form:
CONSTRUCTOR PUBLIC Form( ):
THIS-OBJECT:Create( ).
END.
METHOD PUBLIC INT Create( ): …
DEV-12 What’s New in the Object-Oriented ABL

47. Agenda Overview of Object-oriented ABL 10.1C Features Futures
Static behavior and data
Dynamic programming
Error handling
Data widening, NEW function, reserved keywords, THIS-OBJECT
Futures
DEV-12 What’s New in the Object-Oriented ABL

48. Under Development D I S C L A I M E R
This talk includes information about potential future products and/or product enhancements.
What I am going to say reflects our current thinking, but the information contained herein is preliminary and subject to change. Any future products we ultimately deliver may be materially different from what is described here.
D I S C L A I M E R
DEV-12 What’s New in the Object-Oriented ABL

49. Expected 10.2A Functionality
Properties in Interfaces
Defines data portion of contract
Advanced GUI
New UI Model Access to .NET UI Classes
Garbage collection
Automatic cleanup
Array Enhancements
Arrays of Objects
Public arrays variables and properties
Return value support for methods and functions
Vector assignment
DEV-12 What’s New in the Object-Oriented ABL

50. A Glimpse Further into the Roadmap
Strongly-typed events
Define, Publish and Subscribe in Classes
Remote objects
Pass objects across an AppServer
Abstract methods
Force implementation in subclasses
Inheritance for Interfaces
Allow one Interface to inherit from another
DEV-12 What’s New in the Object-Oriented ABL

51. Relevant Exchange Sessions
DEV-8: Structured Error Handling in the ABL
DEV-22: Catch Me if You Can – Practical Structured Error Handling
DEV-38: OpenEdge ABL Info Exchange
DEV-41: The Power of Polymorphism
DEV-12 What’s New in the Object-Oriented ABL

52. ?
Questions
DEV-12 What’s New in the Object-Oriented ABL

53. Thank You
DEV-12 What’s New in the Object-Oriented ABL

54. DEV-12 What’s New in the Object-Oriented ABL