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Why we use object-orientation

From: Foundations of Programming: Object-Oriented Design

Video: Why we use object-orientation

The most popular programming languages developed in the last 30 years are all Object-Oriented languages, but this wasn't always the way. My first programming job was writing assembly language Cobol and Fortran on mainframes. Now these were not object-oriented languages. They were straight procedural languages where the program is written as a long procedure. Now it might contain named functions and subroutines to make it more modular and maintainable, but it's really a long piece of code, often with all the data, all the variables defined in one place and all the logic in another.

Why we use object-orientation

The most popular programming languages developed in the last 30 years are all Object-Oriented languages, but this wasn't always the way. My first programming job was writing assembly language Cobol and Fortran on mainframes. Now these were not object-oriented languages. They were straight procedural languages where the program is written as a long procedure. Now it might contain named functions and subroutines to make it more modular and maintainable, but it's really a long piece of code, often with all the data, all the variables defined in one place and all the logic in another.

But as programs got bigger and bigger, this proved to be difficult to manage, difficult to plan. And Object-Oriented languages started to gain popularity in the '80s. Now in an Object-Oriented language, this one large program will instead be split apart into self contained objects, almost like having several mini-programs, each object representing a different part of the application. Now each object contains its own data and its own logic, and they communicate between themselves.

Now the idea here is that these objects aren't random. They represent the way you would talk and think about the problem you are trying to solve. They represent things like employees, images, bank accounts, player objects, spaceships, asteroids, video segment, audio files, whatever exists in your program. So object-orientation is what's referred to as a programming paradigm. It's not a language itself but a set of ideas that is supported by many languages.

But is there an alternative to Object-oriented programming? Well, yes and no. There are other approaches to programming. Not just procedural languages like straight C, but if you go through a university computer science course, you might work with logic programming languages like Prolog. Well, functional programming languages like Haskell, but these do tend to be more popular in the academic world or with very specialized uses like computational linguistics. But if you are working or want to work in the practical pragmatic world of creating web applications, mobile apps, desktop applications, game development, you will be using Object- Oriented programming languages.

And your only real choice is do you know what that means or not? So the first question: if everything we do in these languages is Object-Oriented--meaning, we are oriented or focused around objects --exactly what is an object anyway?

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Foundations of Programming: Object-Oriented Design

47 video lessons · 48277 viewers

Simon Allardice
Author

 
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  1. 11m 35s
    1. Welcome
      1m 25s
    2. Who this course is for
      1m 15s
    3. What to expect from this course
      3m 6s
    4. Exploring object-oriented analysis, design, and development
      1m 41s
    5. Reviewing software development methodologies
      4m 8s
  2. 26m 14s
    1. Why we use object-orientation
      2m 42s
    2. What is an object?
      5m 22s
    3. What is a class?
      4m 43s
    4. What is abstraction?
      2m 45s
    5. What is encapsulation?
      3m 45s
    6. What is inheritance?
      3m 35s
    7. What is polymorphism?
      3m 22s
  3. 12m 16s
    1. Understanding the object-oriented analysis and design processes
      4m 13s
    2. Defining requirements
      6m 9s
    3. Introduction to the Unified Modeling Language (UML)
      1m 54s
  4. 23m 35s
    1. Understanding use cases
      6m 11s
    2. Identifying the actors
      4m 16s
    3. Identifying the scenarios
      5m 7s
    4. Diagramming use cases
      4m 18s
    5. Employing user stories
      3m 43s
  5. 16m 36s
    1. Creating a conceptual model
      1m 59s
    2. Identifying the classes
      2m 27s
    3. Identifying class relationships
      2m 38s
    4. Identifying class responsibilities
      6m 43s
    5. Using CRC cards
      2m 49s
  6. 22m 25s
    1. Creating class diagrams
      6m 11s
    2. Converting class diagrams to code
      4m 57s
    3. Exploring object lifetime
      5m 55s
    4. Using static or shared members
      5m 22s
  7. 19m 49s
    1. Identifying inheritance situations
      6m 49s
    2. Using inheritance
      2m 43s
    3. Using abstract classes
      2m 2s
    4. Using interfaces
      4m 20s
    5. Using aggregation and composition
      3m 55s
  8. 9m 23s
    1. Creating sequence diagrams
      5m 18s
    2. Working with advanced UML diagrams
      2m 3s
    3. Using UML tools
      2m 2s
  9. 10m 39s
    1. Introduction to design patterns
      2m 40s
    2. Example: the singleton pattern
      4m 53s
    3. Example: the memento pattern
      3m 6s
  10. 21m 47s
    1. Introduction to object-oriented design principles
      2m 50s
    2. Exploring general development principles
      3m 55s
    3. Introduction to SOLID principles
      6m 43s
    4. Introduction to GRASP principles
      8m 19s
  11. 7m 1s
    1. Reviewing feature support across different object-oriented languages
      3m 50s
    2. Additional resources
      2m 27s
    3. Goodbye
      44s

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