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Introduction to object-oriented languages

From: Foundations of Programming: Fundamentals

Video: Introduction to object-oriented languages

Most programming languages developed in the last 30 years are what are called object-oriented languages. Now this wasn't always the way. My first programming job over 25 years ago was writing assembly language, FORTRAN, and COBOL on ICL mainframes. Now these languages were not object-oriented languages. They were instead straight procedural languages where the program really is written as one long procedure. Even though it might contain functions and subroutines to make it more modular and maintainable, it's really a long piece of code combining data and logic all mixed in together.

Introduction to object-oriented languages

Most programming languages developed in the last 30 years are what are called object-oriented languages. Now this wasn't always the way. My first programming job over 25 years ago was writing assembly language, FORTRAN, and COBOL on ICL mainframes. Now these languages were not object-oriented languages. They were instead straight procedural languages where the program really is written as one long procedure. Even though it might contain functions and subroutines to make it more modular and maintainable, it's really a long piece of code combining data and logic all mixed in together.

Now in an object-oriented language, this program would instead be split apart into self-contained objects, almost like having several mini programs. Each object is representing a different part of the application and each object contains its own data and its own logic and they communicate between themselves. Now if that sounds like it could be a little bit confusing, the idea here is that these objects represent the way you would talk and think about the actual problem.

It's meant to make thinking about your program easier. The objects don't represent mysterious abstract ideas. They first represent things like employees, images, bank accounts, player objects, car objects, whatever actually exists in your program. So object orientation is an idea and it's an idea that it's supported in many languages. And for you it's a shift to thinking about the objects in your program are not just the process. And while object-oriented programming can bring a lot of jargon into the table, there are really only a couple of terms we need to be comfortable with to move forward with it.

The first two terms we need to understand is the difference between a class and an object. And these two terms go hand in hand with object-oriented languages. A class is a blueprint. It's an idea, it's a description, it's a definition. It describes what something is, but it isn't the thing itself. It's a well-defined idea, like say a blueprint for house. And classes will exist for different parts of your program. So if you are writing a restaurant review website, you might create classes that represent a restaurant and a review or a user.

Classes could also represent visual parts of your program, things like TextBox and Button and Window. And they can also represent invisible things like dates and times and anything that can be a well-defined idea. A lot of languages come with many classes already defined, even advanced things like VideoPlayer classes, and you can also define your own. Now all classes describe and define two things: Attributes and Behavior.

What are some things characteristics, its attributes, and what can it do, what's its behavior. So in this case, let's say we are describing a class to describe a person. We might say that the person attributes are name, height, weight, gender, and age, whereas the person's behavior is walk, run, jump, speak, sleep. Think about it this way that the attributes are really your data, your variables. And the behavior is what can you do, your functions. And actually attributes and behavior in most object-oriented languages are actually described with other names, which is properties and methods.

These are the most common ways of describing these. But the class is describing these things in abstract. And what I mean by that is it says that a person has a name and it has a height, but it doesn't say what the name is because the class is just the description of something. But just like there's no point creating a blueprint if you never intend to make a house, there's no point defining a class unless you're going to make an object. So that's the relationship between the two.

The class is the idea and the object is the thing itself. We create objects based on the class like creating a house based on the blueprint. Not only that, but you can create multiple objects based on one class in the same way you could create multiple houses based on one single blueprint. Now while there is a lot of jargon associated with object orientation, encapsulation is the key idea.

This the idea that classes are self- contained units that represent both the data and the code that works on that data, that we take our properties and our methods and we box them up, we encapsulate them. JavaScript is an object-oriented language. Although it is quite casual with it, there are some other languages where object orientation is very formal and you can do very little without thinking deeply about classes and objects. So while some languages like C are not at all object-oriented, if you're working in Java, C#, Ruby, Python, VB.NET, Objective-C, you can't avoid object orientation in most modern programming languages.

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This video is part of

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Foundations of Programming: Fundamentals

61 video lessons · 88535 viewers

Simon Allardice
Author

 
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  1. 4m 15s
    1. Welcome
      1m 17s
    2. Making the most of this course
      2m 8s
    3. Using the exercise files
      50s
  2. 22m 11s
    1. What is programming?
      5m 45s
    2. What is a programming language?
      4m 48s
    3. Writing source code
      5m 34s
    4. Compiled and interpreted languages
      6m 4s
  3. 16m 29s
    1. Why JavaScript?
      4m 45s
    2. Creating your first program in JavaScript
      6m 54s
    3. Requesting input
      4m 50s
  4. 31m 38s
    1. Introduction to variables and data types
      5m 16s
    2. Understanding strong, weak, and duck-typed languages
      3m 51s
    3. Working with numbers
      5m 4s
    4. Using characters and strings
      4m 5s
    5. Working with operators
      4m 47s
    6. Properly using white space
      6m 46s
    7. Adding comments to code for human understanding
      1m 49s
  5. 24m 48s
    1. Building with the if statement
      7m 35s
    2. Working with complex conditions
      4m 9s
    3. Setting comparison operators
      6m 59s
    4. Using the switch statement
      6m 5s
  6. 17m 54s
    1. Breaking your code apart
      4m 1s
    2. Creating and calling functions
      2m 56s
    3. Setting parameters and arguments
      6m 7s
    4. Understanding variable scope
      2m 23s
    5. Splitting code into different files
      2m 27s
  7. 13m 31s
    1. Introduction to iteration
      4m 28s
    2. Writing a while statement
      5m 24s
    3. Creating a for loop
      3m 39s
  8. 19m 28s
    1. Cleaning up with string concatenation
      4m 30s
    2. Finding patterns in strings
      8m 3s
    3. Introduction to regular expressions
      6m 55s
  9. 19m 58s
    1. Working with arrays
      5m 46s
    2. Array behavior
      5m 29s
    3. Iterating through collections
      5m 18s
    4. Collections in other languages
      3m 25s
  10. 10m 50s
    1. Programming style
      5m 55s
    2. Writing pseudocode
      4m 55s
  11. 25m 55s
    1. Input/output and persistence
      3m 6s
    2. Reading and writing from the DOM
      8m 11s
    3. Event driven programming
      7m 47s
    4. Introduction to file I/O
      6m 51s
  12. 24m 25s
    1. Introduction to debugging
      5m 57s
    2. Tracing through a section of code
      7m 5s
    3. Understanding error messages
      3m 21s
    4. Using debuggers
      8m 2s
  13. 14m 16s
    1. Introduction to object-oriented languages
      5m 18s
    2. Using classes and objects
      6m 28s
    3. Reviewing object-oriented languages
      2m 30s
  14. 11m 14s
    1. Memory management across languages
      5m 11s
    2. Introduction to algorithms
      4m 2s
    3. Introduction to multithreading
      2m 1s
  15. 29m 20s
    1. Introduction to languages
      1m 42s
    2. C-based languages
      4m 40s
    3. The Java world
      3m 13s
    4. .NET languages: C# and Visual Basic .NET
      6m 17s
    5. Ruby
      3m 4s
    6. Python
      2m 56s
    7. Objective-C
      4m 3s
    8. Libraries and frameworks
      3m 25s
  16. 1m 2s
    1. Where to go from here
      1m 2s

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