Saturday, December 11, 2010

What is an Object?

Objects defined

So what is an object? An object is a component of a program that knows how to perform certain actions and to interact with other pieces of the program. Functions have previously been described as "black boxes" that take an input and spit out an output. Objects can be thought of as "smart" black boxes. That is, objects can know how to do more than one specific task, and they can store their own set of data. Designing a program with objects allows a programmer to model the program after the real world. A program can be broken down into specific parts, and each of these parts can perform fairly simple tasks. When all of these simple pieces are meshed together into a program, it can produce a very complicated and useful application.
Let's say that we are writing a text-based medieval video game. Our video game will have two types of characters: the players and the monsters. A player has to know the values of certain attributes: health, strength, and agility. A player must also know what type of weapon and what type of armor they possess. A player must be able to move through a maze, attack a monster, and pick up treasure. So, to design this "player object", we must first separate data that the player object must know from actions that the player must know how to execute. The definition for a player object could be:
Player Object:
    type of weapon
    type of armor
    attack monster
    get treasure

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