What is Object Oriented Programing?!

[B-Man 31]

Hey, i was wondering if someone could explain to me who OOP works, i believe my current style is procedural programming but im not sure 100% what either is, any clarifications would help. I have wikipedia'd it but its not making much sense to me so if anybody knows how to explain it an a easy-to-understand way, i would greatly appreciate it

[Tony]

Super short version:

In "procedural" paradigm, you have a world (your program) filled with global types and functions. You might have something like:

code:

function cat_speak(my_cat : cat)    put my_cat.name, " says: LOL" end cat_speak function dog_speak(my_dog : dog)    put my_dog.name, " says: ROFL" end dog_speak

OOP allows you to create a system of classes that models the world in terms of "objects". Everything is an "object" and those objects can perform "methods". Ultimately it will allow you to write code in a form of

code:

my_pet.speak()

And the pet will figure out on its own if it's a cat or a dog, and how it should speak.

---------------

Obviously the above leaves out most of the details, but ultimately different programming paradigms (see http://en.wikipedia.org/wiki/Programming_paradigm) are about different ways of representing elements of the program, and defining their interactions.

[Superskull85]

I like to think of OOP as the ability to box off different groups of information.

For example, you can think of water as an object. You can drink the water, boil the water, put the water in a container, mix other liquids with it, etc. Unless you are a chemist, you don't care how it is composed, why it does what it does or why it even exists. All you care about is that it can keep you hydrated and you are able to use it to create something else.

Another example is creating a "Rectangle" object. The rectangle could of been created using four lines, a fill colour and used an external class. However, all you care about is that it can be drawn to screen, you can move it around, change the colour, change the size, etc.

Basically each class is able to create an object that you can do stuff with. You do not want/need to worry about how the object was created, or why it works (unless you are expanding on a class), as it does what it is supposed to do.

There is a lot of different concepts in OOP, so if you have a specific problem I can provide a more specific analogy/answer.

[B-Man 31]

no, i dont have any more questions, is there any tutorials on how i could learn OOP here on compsci, i heard its a lot more efficient. And i think im starting to understand. as much info would be appreciated. Thanks Tony and Superskull85 for you input.

[Insectoid]

That's a question that has stumped many a new programmer.

You've been doing procedural programming. That means you have one program that holds every variable, every procedure and function. Almost anything can do anything to anything. It's rather linear, and you can follow through with it from the top down.

Object-oriented programming is slightly different, in that there is a main program which controls most things, as well as 'objects'. These can be thought of a sub-programs that you can use in your code. These objects are 'imprints' if you will of a class. a class is a template for an object. A common example is the String class. Classes can contain functions (also called methods and other things), as well as straight data (aka variables). An object is an instance of a class. Kind of like a cookie cutter. A class is the cutter, and it can make many cookies.

For example, we have made a Circle class. It has a variable for the radius. It also has several functions to calculate the circumference and area. With this, we can create a number of different circles of different radii and it will do the rest of the work for us. Let's have some pseudo code:

code:

class Circle (radius:double){     function circumference{               return 3.14*radius**2     }     function area {         return 2*3.14*radius     } }

Now, we can create an instance of this class, an Object:

code:

var foo = Circle.new (5)

We have now created a circle with a radius of 5. We can access this information with dot notation. This is different from procedural programming. You're probably used to:

code:

procedure doThis (x:int){     //do something } doThis (5)

dot notation uses a dot (.) to call functions within a class

code:

var x = foo.area

Now, let's make another Circle;

code:

var baz = Circle.new (10) //create a circle of radius 10 var y = baz.area

I'm calling the area function, but from the baz object. It will return 2*3.14*10, whereas foo.area will return 2*3.14*5.

This is a very brief explanation, I hope I got something across.

I think the equations might be mixed up. I can never keep them straight.

[DtY]

B-Man 31 @ Mon Nov 09, 2009 7:59 pm wrote:

no, i dont have any more questions, is there any tutorials on how i could learn OOP here on compsci, i heard its a lot more efficient. And i think im starting to understand. as much info would be appreciated. Thanks Tony and Superskull85 for you input.

What language do you want to learn? Do you already know a programming lamguage, it might already have some OOP.
If you don't already know a language that has OOP, or want to start fresh, learn Ruby. In my experience, it is the "most" OOP language.
I'm not sure where to find it, but my first experience with Ruby was an online Ruby interpreter that ran in the browser, and had a tutorial that walked you through various things you can do, without having to download anything. If anyone knows where to find that, it would be appreciated.

[Insectoid]

Ah hell, you guys fit 3 posts in while I was typing up mine? I am getting slow. Or long-winded. I dunno which.

[DtY]

insectoid's description is really good, but I feel the need to point out that that is specifically class based OOP, which is probably what you will be working with, unless you use Javascript. (Which is prototype based OOP)

[Insectoid]

Well, I've only ever used class-based OOP. And I recommend learning OOP with Ruby. Java was a pain in the ass for me, as it tries to do far too much for you and confuses the hell out of you. Ruby is simple, and yet somehow superior to the far more popular (and criticized) Java.

[Tony]

DtY @ Mon Nov 09, 2009 8:09 pm wrote:

an online Ruby interpreter that ran in the browser

http://tryruby.sophrinix.com/

Edit: also Ruby is completely Object-Oriented (Smalltalk style), while Java still has non-object native types (int vs. Integer).

Edit2: by "popular" you obviously mean "more widely used".

[B-Man 31]

instectiod, thank you so much, im starting to understand even though the code you wrote it in is C++ i believe, it still makes sense because i know basic C++, i was mainly wondering for Turing because i am getting bored in class and its seems too easy. no matter how many things i try to add. i decided learning OOP might be a good way to challenge myself. You guys seem to know quite well what your doing so in turing your liitle program would be like:

Turing:

class circle     export circumference, area     function circumference (radius : real) : real         result 3.14 * radius ** 2     end circumference     function area (radius : real) : real         result 2 * 3.14 * radius     end area end circle var test : pointer to circle new circle, test test -> area (5.12) put test.area

This doesn't seem to work so can anyone tell me what im doing wrong, thanks

[Tony]

It's not C++.

Quote:

Let's have some pseudo code

I think you might be looking for something like

code:

new circle, test put test -> area (5.12)

[B-Man 31]

Tony @ Mon Nov 09, 2009 8:35 pm wrote:

I think you might be looking for something like

code:

new circle, test put test -> area (5.12)

Why Thank you, that did the trick

This is basically what i have now, this is OOP then (very simply of course)

Turing:

class circle     export circumference, area         function circumference (radius : real) : real         result 3.14 * radius ** 2     end circumference     function area (radius : real) : real         result 2 * 3.14 * radius     end area     end circle var radius : real var test : pointer to circle loop     new circle, test     put "please enter radius: " ..     get radius     put "the area is: ", test -> area (radius)     put "the circumference is: ", test -> circumference (radius), skip end loop

[EDIT:] Also can anyone tell me the advantages and disadvantages of OOP?

[Insectoid]

I find OOP is a lot more organized if used well. You know exactly what is what and what can do what. Procedural programming can quickly turn into a mess since there's not much in the way of organization.

[B-Man 31]

now i am starting to understand for basics like this circle class, but what if you wanted to make a more visual and bigger harder program, how would you use OOP/classes?