Object-Oriented Programming and the Progress ABL Tomáš Kučera Principal Solution Engineer / EMEA...

Object-Oriented Programming and the Progress ABL

Tomáš KučeraPrincipal Solution Engineer / EMEA Power Team

© 2007 Progress Software Corporation2

> whoami

Started with Progress Software Czech Republic – Dec 19, 1994

2 years @ Technical Support (1996 at ETSC) Since Dec 1996 – Consultant, Presales, Trainer,

Project Manager Currently – GFS Mgmt responsibilities for Cze&Pol,

Member of the EMEA Power Team – primary responsibility for SAND

Product Areas: OpenEdge, Sonic, some Apama and Actional

Contact: [email protected], Skype: tomas_kucera

TKU


Agenda

Obligatory Theory Simple Sample


What are Objects?

You interact with objects everyday• A customer• An order

All objects contains state and behavior• What they can do and what changes when they do

Software objects represent these as:• Data ( like 4GL variables )• Methods ( like 4GL procedures)

• Your car

• The telephone


Object-Oriented Principles

Abstraction• Break up complex problem• Focus on public view, commonalities

Encapsulation • Hide implementation details• Package data and methods together

Hierarchies• Build new objects by referencing or

extending other objects


Type• Enforces type consistency at compile time

Class• Defines type with data and methods and

provides implementation

Object• Runtime instantiation of class

Interface• Defines type with only methods – no

implementation provided

Object-Oriented Constructs


Why should I care about Object-Orientation?

Object-orientation is a highly structured way to build applications• Simpler modeling tool integration, e.g.

roundtrip engineering

Code benefits• Less bugs

• More reuse

Business benefits• Time to market

• Better maintainability

Object-orientation’s big benefits


Why should I care about Object-Orientation?

Strong Typing• Less runtime processing

• Improved quality through finding errors at compile-time

• Class hierarchy known at compile-time

Re-use• Abstraction means code re-use

• Classes can be deployed for re-use

• Improved quality and higher productivity

How do we get the benefits?


Requires more forethought than procedural• Type hierarchies can be hard to change

– Refactoring and modeling can help

Requires a base class library to get started• Base classes can take a while to build

Different mindset from procedural• Easier, if you have worked with super

procedures before

Unfortunately it is not totally free


Object-Orientation versus Procedural

“Types” are created at run-time

Type definition is loosely bound

Inheritance is determined at run-time

Provides flexibility for generic code

Types are known at compile time

Type definition is contractual

Inheritance is set at design-time

Prevents run-time type errors

Procedural OO


Mapping Procedures to Classes

Procedure Files (.p) Main block code Internal Procedures Functions ON CLOSE Super procedures

Class Files (.cls) Constructor Void Methods Method Destructor Inheritance

Procedure Class


Agenda

Obligatory Theory Simple Sample


Simple Sample

Create a solution using Progress OOABL that will perform the following:• Feature #1- it will retrieve data from a specific

database table into a temp-table based on provided WHERE phrase and will provide access to it

• Feature #2 - it will check access privileges to the table

• Feature #3 - it will display the data

The Scenario


Simple Sample

Standard Progress ABL Sophisticated Progress ABL with includes,

persistent procedures, super procedures Progress OOABL

Quiz: The Approach


Simple Sample

Standard Progress ABL Sophisticated Progress ABL with includes,

persistent procedures, super procedures Progress OOABL

Answer: The Approach


Simple Sample

Encapsulation Inheritance Typing Interfaces Polymorphism Delegation

What we will see and will not see

Encapsulation Inheritance Typing Interfaces Polymorphism Delegation


Simple Sample

The Modelclass SimpleSample

«BusinessEntity»BusinessEntity

+ h_entity: HANDLE+ h_query: HANDLE

+ Constructor() : void+ Destructor() : void+ RetrieveData(CHARACTER) : void- CheckAccess() : LOGICAL

«BusinessEntity»BECustomer

+ h_custnum: HANDLE+ h_name: HANDLE

+ Constructor() : void+ Destructor() : void+ RetrieveData(CHARACTER) : void

«inherits»


Simple Sample

Let‘s do it!


Question?

Tomáš Kuč[email protected]: tomas_kucera

customer


Where to get more

Information resources

OpenEdge Documentation:• Getting Started: 10.1B Object-oriented

Programming manual PSDN - www.psdn.com

• Library – Products – OpenEdge – Development Tools & Language – Advanced Business Language (ABL)

• Library – Product Documentation – OpenEdge Release 10.1B Product Documentation – Getting Started

Object-Oriented Programming and the Progress ABL Tomáš Kučera Principal Solution Engineer / EMEA...

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