Object-oriented
programming in the
Progress® 4GL
10.1A Beta
Salvador Viñals
Consultant Product Manager
svi@progress.com
OpenEdge 10.1A1B Beta
Agenda
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Introduction and goals of OO in the 4GL
Concepts and overview
An example
Tools support for OO in the 4GL
Beta use cases
2 © 2005 Progress Software Corporation
Object-oriented
Application Development

A way to design and build applications
– Objects bundle together data (state) and
methods (behavior)
– Objects facilitate separating definition from
implementation

Much more than just syntax
– You might have already done object-oriented
programming in the 4GL
3 © 2005 Progress Software Corporation
Object-orientation and the 4GL
Goals

Extend the 4GL to support the OO
programming model
– Retain existing strengths

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A natural basis for OpenEdge Reference
Architecture applications
Programming with classes
More closely support SOA
Multiple rollouts
– 10.1A first one
4 © 2005 Progress Software Corporation
OO in the 4GL Features
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CLASS definitions
Single inheritance hierarchies
Data members and methods
Interfaces
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Benefits of OO in the 4GL
Programming
Business
Encapsulation
Maintenance
Inheritance
Promotes reuse
Code reuse
Productivity
Interfaces
Contracts
Strong typing
Robustness
Invocation model
Ease of use
Maps modeling tools
Efficient dev cycle
.cls - .p interoperability
Not disruptive
6 © 2005 Progress Software Corporation
Poll

Are you familiar with Object-oriented Programming
concepts?
– Type
– Class
– Data members and methods
– Interface
– Inheritance
– Polymorphism
– Objects
<Please “click” Yes or No,
using the menu-bar>
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Poll

How many using SUPER-PROCEDURES?
<Please “click” Yes or No,
using the menu-bar>
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Similarities between
Classes and Procedures
Procedures
Classes
Procedure files (.p)
Class files (.cls)
Define variables
Data members
Internal procedures
VOID methods
User defined functions
Other methods
Code in main block
Constructor
Super-procedures
Inheritance
9 © 2005 Progress Software Corporation
Interoperability
Procedures and Classes
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Procedures
–
–
–
–

Can NEW a CLASS
Can DELETE an object
Invoke methods using object reference
Can pass object reference as a parameter
Classes
– Can RUN a procedure
– Can invoke internal procedure / udf using
procedure handle
10 © 2005 Progress Software Corporation
Agenda





Introduction and goals of OO in the 4GL
Concepts and overview
An example
Tools support for OO in the 4GL
Beta use cases
11 © 2005 Progress Software Corporation
Object-Oriented Concepts
What do I need to understand before I learn OO4GL?
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OO terminology for familiar concepts
– Classes, types, data members, methods & objects
Encapsulation
– Grouping data & behavior together
Inheritance
– Re-using and extending code
Delegation
– Letting contained objects do their own work
Polymorphism
– Generic code for objects with common data & behavior
Interfaces
– Implementing a standard set of methods
12 © 2005 Progress Software Corporation
Types
A Type is a definition

Each class represents a new data type
– Variables, parameters, return types

Allows for strong-typing
– Early binding - types determined at
compile time
– Type-consistency enforced at compile time
and runtime
13 © 2005 Progress Software Corporation
Types – An Example
Types:
 Order
Order
is a
InternalOrder
is a

– Sub-Type of
Order
ExternalOrder

A Sub-Type can appear anywhere
a Super-Type is expected
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InternalOrder
ExternalOrder
– Sub-Type of
Order
Benefits of Types
Strong Typing

Compile time checking for type consistency
myObj = mySubObject.
myObj:method(…).
myObj:data = 3.
(must be Sub-Type)
(validates signature)
(validates data type)

Results in safer, bug-free code because all
code paths checked at compile time

Develop super-classes first
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Class
A Class implements a Type

A Class is a template
(blueprint) for an
object:
– Data
– Methods
– Relationships to other
classes
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Data
A Class defines and
implements a
user-defined type
orderNum AS INT
custNum AS INT
CalculateTotalPrice( )
Methods

Class: Order
PUBLIC:
CreateOrder( )
UpdateOrder( )
GetOrderTotal( )
Next( )
The CLASS Construct
CLASS [<package>.]<class-name>
[INHERITS <super-type-name> ]
[IMPLEMENTS <interface-type-name>
[,<interface-type-name>]…]
[ FINAL ]:
[
[
[
[
<data member> …]
<constructor> ]
<method> … ]
<destructor> ]
END [ CLASS ].
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The CLASS Construct
CLASS [<package>.]<class-name>
[INHERITS <super-type-name> ] • Use packages to
[IMPLEMENTS <interface-type-name>
group classes
[,<interface-type-name>]…]
• Package maps to
[ FINAL ]:
physical file relative
to PROPATH
[ <data member> …]
[ <constructor> ]
at compile time
[ <method> … ]
AND run time
[ <destructor> ]
• Period “.” maps to
slash “/”, “\” in
END [ CLASS ].
directories
CLASS Acme.Inventory.Order: …
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The CLASS Construct
• Use inheritance to
abstract out
CLASS [<package>.]<class-name>
common data and
[INHERITS <super-type-name> ]
[IMPLEMENTS <interface-type-name> functionality
[,<interface-type-name>]…]
• Sub-classes inherit
[ FINAL ]:
all data members &
methods from their
[ <data member> …]
super-classes
[ <constructor> ]
• Sub-classes may
[ <method> … ]
extend or change
[ <destructor> ]
behavior by
overriding
END [ CLASS ].
methods of superclass
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The CLASS Construct
Classes are always
PUBLIC
CLASS [<package>.]< <class-name>
[INHERITS <super-type-name> ]
[IMPLEMENTS <interface-type-name>
[,<interface-type-name>]…]
[ FINAL ]:
Encapsulation through
class members:
[ <data member> …]
• Data
[ <constructor> ]
• Methods
[ <method> … ]
[ <destructor> ]
Access types:
END [ CLASS ].
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• PUBLIC
• PRIVATE
• PROTECTED
The Class File

Filename consists of package and class
name
– One class per file


.cls extension
Compiles to r-code
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Creating Class Instances
The NEW statement (equivalent to RUN)
<obj-ref> = NEW <type-name> ([<parameter>[,…]])
[ NO-ERROR ].

Example
DEFINE VARIABLE myOrder AS
Acme.Inventory.Order NO-UNDO.
myOrder = NEW Acme.Inventory.Order ( ).
22 © 2005 Progress Software Corporation
Agenda





Introduction and goals of OO in the 4GL
Concepts and overview
An example
Tools support for OO in the 4GL
Beta use cases
23 © 2005 Progress Software Corporation
Object-orientation – An Example

Application needs to manage two sets of orders for
the same items:
– Customer orders
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Need to check valid customer and credit-limit
Charge
Shipping and logistics
– Internal orders
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Need to check valid department and cost center
No charge
Internal delivery
– Inventory is common
24 © 2005 Progress Software Corporation
Access Levels
Accessible by
super-class
only
Class Order
DEF PRIVATE VAR OrderNum AS INT
DEF PRIVATE VAR CustNum AS INT
DEF PRIVATE VAR ShipDate AS DATE
Private
DEF PRIVATE VAR OrderStatus AS CHAR
METHOD PROTECTED … calculatePrice()
Protected
Accessible
by superclass & subclasses
METHOD PUBLIC VOID calculateTax()
METHOD PUBLIC VOID initOrder()
METHOD PUBLIC VOID updateOrder()
METHOD PUBLIC CHAR getCustomer()
METHOD PUBLIC CHAR getShipDate()
METHOD PUBLIC CHAR getStatus()
METHOD PUBLIC DEC getOrderTotal()
25 © 2005 Progress Software Corporation
Public
Accessible by
super-class, subclasses & other
classes
Inheritance Hierarchy
Class Order
InternalOrder Class
DEF … OrderNum AS INT
INHERITS Order
DEF … CustNum AS INT
DEF … ShipDate AS DATE
Inherit
from
DEF … CostCenter AS INT
DEF … Department AS INT
DEF … OrderStatus AS CHAR
METHOD … getCostCenter()
METHOD … calculatePrice()
METHOD … getDepartment()
METHOD … calculateTax()
METHOD … initOrder()
ExternalOrder Class
METHOD … updateOrder()
INHERITS Order
METHOD … getCustomer()
METHOD … getShipDate()
METHOD … getStatus()
METHOD … getOrderTotal()
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DEF … CustNum AS INT
DEF … CreditLimit AS DEC
METHOD … verifyCredit()
METHOD … getCustNum()
Polymorphism
These objects of class types derived from Order may each
behave differently when sent the InitOrder() message:
myInternalOrder
myExternalOrder1
myExternalOrder2
CostCenter = 9145
CustNum = 10
CustNum = 11
Department = 5
CreditLimit = 50000
CreditLimit = 300000
InitOrder
InitOrder
if isValid(getCostCenter() and
If (isValid(getCustNum()) and
getDepartment())
verifyCredit())
then call super-class’ initOrder()
then call super-class’ initOrder()
else call super-class’ rejectOrder()
else call super-class’ rejectOrder()
27 © 2005 Progress Software Corporation
Delegation
Class GuiHandler
FirstButtonPressed()
Class Navigator
LastButtonPressed()
GuiHandler myGui
NextButtonPressed()
QueryHandler myQuery
PrevButtonPressed()
OkButtonPressed()
CancelButtonPressed()
initNavigator()
First()
Last()
Next()
Prev()
Cancel()
OK()
Contains
Class QueryHandler
OpenQuery()
CloseQuery()
GetFirstRec()
GetLastRec()
GetNextRec()
GetPrevRec()
28 © 2005 Progress Software Corporation
Agenda





Introduction and goals of OO in the 4GL
Concepts and overview
An example
Tools support for OO in the 4GL
Beta use cases
29 © 2005 Progress Software Corporation
Tools Support For OO in the 4GL

OpenEdge Architect
– Code editors
– Tools for Business Logic
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Not in this beta
Business Entity Designer
OpenEdge Studio (AppBuilder)
4GL Development System (Procedure Editor)
Application Compiler
Debugger
– Compile  Debug requires stub
30 © 2005 Progress Software Corporation
Rules For .cls Files
All editing environments
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Must have .cls extension to compile
– Added to file filters

File and package name in class file must
match physical location
CLASS payroll.taxcalc:
…
END CLASS.

Must save file to run
31 © 2005 Progress Software Corporation
AppBuilder Support
Procedure Window
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No AppBuilder changes to support class files
Opened as unstructured procedures in
Procedure Window
AppBuilder Procedure Window
– Same support as Procedure Editor

Procedure Window supports remote
development
– Web-disp.p cannot instantiate class files
32 © 2005 Progress Software Corporation
Procedure Editor Support
File filters
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New “*.cls” filter in GUI
– File open
– Save
– Save As
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Source file types
– All Source (*.p, *.w, *.i, *.cls)
– Classes (*.cls)

TTY has no filters
33 © 2005 Progress Software Corporation
Syntax Checking
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Checking syntax of named edit buffers
– Create temp directory(s)
– Contains class file of correct name

Checking syntax of unnamed edit buffers
– Saves to temp file of .cls extension
– In current working directory

An inherited super-class must be in
PROPATH for sub-classes to syntax check
34 © 2005 Progress Software Corporation
Application Compiler

Includes ‘.cls’ extension
May compile super-classes

“Remove Old .r Files”
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– Super-classes .r is not
removed when compiling
sub-classes

“Only Compile if No .r File”
36 © 2005 Progress Software Corporation
Agenda





Introduction and goals of OO in the 4GL
Concepts and overview
An example
Tools support for OO in the 4GL
Beta use cases
37 © 2005 Progress Software Corporation
Current Beta Use Cases (1/4)
Use Case ID:
Use Case Name:
Description
Actors
Assumptions
Steps
Expected results
or end state
101A4GL500
OO4GL new design/development
Apply Object-Oriented design principles to new 4GL application
4GL architect/designer/developer
Knowledge of OO concepts
1. Identify a new (not yet designed/implemented) 4GL application or new
component of an existing 4GL application
2. Create an object-oriented design for 4GL application:
a. define architecture
b. analyze components
c. determine data model
d. determine object model
e. define class hierarchies
3. Use new 4GL programming constructs to create user-defined classes for
the design
Verify that the 4GL constructs provided are sufficient to implement your
OO design.
38 © 2005 Progress Software Corporation
Current Beta Use Cases (2/4)
Use Case ID:
Use Case Name:
Description
Actors
Assumptions
Steps
Expected results
or end state
101A4GL501
OO4GL existing OO model
Transform existing ‘OO’ 4GL app to use new OO4GL constructs
4GL architect/designer/developer
Knowledge of OO concepts
1. Identify an existing 4GL application (or component) that employs OO
concepts, implemented with existing 4GL constructs, such as SUPER
Procedures.
2. Use new 4GL programming constructs to implement the existing ‘OO’
design
Verify that the new 4GL constructs are sufficient to provide the same
functionality as the existing 4GL features.
39 © 2005 Progress Software Corporation
Current Beta Use Cases (3/4)
Use Case ID:
Use Case Name:
Description
Actors
Assumptions
Steps
Expected results
or end state
101A4GL502
OO4GL implementation through user-defined classes
Exercise the new OO4GL constructs
4GL architect/designer/developer
Knowledge of OO concepts
1. Start with an OO-designed 4GL application based on the new 4GL
features (see Use Case “101A4GL500 and 101A4GL501”)
2. Write 4GL code using the new language constructs that implement:
a. inheritance
b. overriding
c. polymorphism
d. public/private/protected methods
e. public/private/protected data members
i. temptables
ii. buffers
iii. queries
iv. built-in datatypes
f. methods with VOID and non-VOID return values
g. constructors and destructors
Verify that the new 4GL features work according to the specified behavior.
40 © 2005 Progress Software Corporation
Current Beta Use Cases (4/4)
Use Case ID:
Use Case Name:
Description
Actors
Assumptions
Steps
Expected results
or end state
101A4GL503
OO4GL use of User Defined Classes
Use new OO4GL User-defined Classes as data types
4GL architect/designer/developer
Knowledge of OO concepts
1. Implement a new 4GL application (or component) using the new 4GL
constructs (see Use Case “101A4GL502”)
2. Instantiate your user-defined classes, and use them as you would builtin datatypes:
a. Pass as parameters
b. Pass as return values
c. Use as temptable fields
d. Delete them
Verify that the user-defined classes’ methods and data members are
accessible and behave as expected throughout these steps.
41 © 2005 Progress Software Corporation
In addition, you shall …

Validate interoperability

Gather information about increase in development /
maintenance productivity

"Benchmark" runtime performance through testing
of your user-defined classes

Share your findings
– Multiple ways to design, organize any given
functionality
42 © 2005 Progress Software Corporation
In Summary

Standard OO concepts available in
the 4GL

Built on top of existing 4GL
constructs

Interoperability with Procedure /
Functions
– Can be combined with procedural
programming, not all or nothing

Many benefits in OO Programming

Major difference of OO: Enforcement
43 © 2005 Progress Software Corporation
Questions?
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Thank you for
your time!
45 © 2005 Progress Software Corporation
46 © 2005 Progress Software Corporation