Object Thinking

Object Thinking

The Philosophy of Developmentformalism -vs- hermeneutics

From Philosophy to Culturementoring, metaphor &

vocabulary

From Culture to Practiceobject discovery & thinking

Formalism/Determinism(software engineering)

uses traditional thinking

-vs-

Hermeneutics/Postmodernism(extreme programming)

uses object thinking

The Object Thinking Manifesto

Advocacy of behavioralismAntagonistic towards formalism

Emphasis on analysis and conceptualization

Philosophy of extreme programming

Prefers the autonomous to the autocratic

The Object Thinking Manifesto

Better people write better code

- not better tools

“Let there be no doubt that object-oriented design is fundamentally

different than traditional structured design approaches:

it requires different ways of thinking about decomposition, and it produces software architectures that are largely outside the realm of the structured design culture.”

Grady Booch, 1991

“Let there be no doubt that object-oriented design is fundamentally

different than traditional structured design approaches:

it requires different ways of thinking about decomposition, and it produces software architectures that are largely outside the realm of the structured design culture.”

Grady Booch, 1991

Observing the Object Difference

Traditional thinking Object thinking

Data Structure

operationX

operationY

operationZ

Anthropomorphizationis the attribution of human

characteristics to inanimate objects,

animals, forces of nature, the unseen author of things, and others.

“… if the diagram is an accurate depiction of an object, what is

the difference between an object and a COBOL program?”

“There is none. A COBOL program encapsulates data and operations and allows communication among programs. Object development –

using this model – will have a tough time being anything more than the creation of lots of tiny

COBOL programs.”

Object Depictions

Entity UML

Customer

ID#dobgenderfname…

getID#setID#getDOB#setDOB#…

Customer

id#dobgenderfnamelnamemihonorificgenerational…

Object Depictions

Object (Class-Responsibility-Collaboration)

Customer

ID selfdescribe selfindicate desiresmake decisionsconfirm information

Encapsulation via Properties

public class Customer{ public string Name { get { return _name; } set { // validate here _name = value; } }

private string _name;}

• Known as information hiding

• Traditionally taught as a key precept of OO

• But many XP advocates say they should not be tested … why?

• Why do objects keep trying to change type?

• Is there a better way?

Self-Describing Objectspublic class Customer : Dictionary<Uri,

Object>{ }

• Provides a property bucket

• Looks alien to traditional thinking

• Violates traditional encapsulation principles

• How is validation carried out?

Self-Evaluating Rules

Evaluate self-describing objects at runtime

Promote type re-use via separation of concerns

Embody data validation rules, business rules, or any other constraint

Demo

Self-Describing Objects & Self-Evaluating Rules

So all my objects should be self-describing?

Having a hammerdoes not make everything a nail

Non-Self-Describing ObjectsPrimitives

bool, int, float, enum, etc.

Some Standardshtml elements, xpath predicates, industry,

etc.

Self-Describing Objects tend to be actors

Issues

Currently no standard supporting frameworkI am considering a CodePlex or SourceForge

project

Limited knowledge, few publications, no examples

Just try googling for the key terms…

Steep learning curveHard to ‘unlearn’ traditional thinking

Few practitioners or evangelists

Linkshttp://del.icio.us/alan.dean/object-

thinking

http://thoughtpad.net/alan-dean

Emailalan.dean@thoughtpad.net

© MMVII