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What is an Object Anyway?

What is an Object Anyway?. IMAT1604 Visual Web Development. What is an Object Anyway?. What is a word? Think about the following word… Shop What springs to mind?. A Specific Shop. The act of shopping…. Creating Instructions.

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What is an Object Anyway?

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  1. What is an Object Anyway? IMAT1604 Visual Web Development

  2. What is an Object Anyway? • What is a word? • Think about the following word… Shop • What springs to mind?

  3. A Specific Shop

  4. The act of shopping…

  5. Creating Instructions • A word on its own isn’t much use to us however when we combine it with other words we can create instructions. • “I want you to go to the shop and get me a tin of peas.”

  6. Words are Really Just Symbols • What is this?

  7. What if we add other symbols? • Traffic lights and words on a page are all the same they are all symbols that we look at and assign meaning.

  8. What is Programming? • Programming is about using words and symbols to communicate with a Computer • As with our example above we use words / symbols to create instructions or functions that the computer will follow and perform some task. • Functions are organised into classes – text files

  9. Who is this? • More to the point why is she so irritating? • We need to use the right words correctly

  10. Most of us end up feeling more like this...

  11. The Importance of Vocabulary “Shop, street, road, post box, lamp post, post code, house, flat, house number, left, right ahead, distance, time, street sign, landmark.” • These words make up the vocabulary of the streets and roads. We are familiar with these words and can easily make up instructions (functions) using these words. “You want to walk down that street for 10 meters then turn left at the post box. You will then see a sign to the railway station. Follow that sign for 5 meters and the shop is on the left.”

  12. Computer Programming Introduces a new Vocabulary “Class, object, assignment, sequence, variable, RAM, parameter, data type, function, method, property, selection, sequence, integer, string.”

  13. The Computer Programmer • The person who knows how to write the correct words / symbols to tell the computer what to do • Computers copy and process data • Data is made of binary numbers • Nobody really likes binary • We need a set of commands to control data

  14. First Look at Some C# Code • What is wrong with this?

  15. The Problem • Computers are really fussy • Spotting errors can be difficult at first • This gets easier with practice • Take a look at the following… Int32 Name; - Variable Name(); - Function “Name” - A string of letters .Name - A method or a property (Probably a property) //Name - A comment (Name) - A parameter

  16. New Terms to Understand • Function • Method • Property • Class • Instantiation • Object

  17. Functions • “A function is sequence of words and symbols that instruct the computer to perform a single action on some data well.”

  18. Methods and Properties • Method • A function that acts on the data in some way • E.g. Multiply • Property • A function that allows us to find out something about the data or to set some aspect of it. • E.g. Count • (This will be confusing at first!)

  19. Classes • A class is a text file that contains related functions making them easier to manage • Classes are like recipe books • Recipe books dedicated to specific regions • Classes dedicated to specific sets of functionality • A student manager class might contain… • Methods • .AddStudent • .UpdateStudent • .DeleteStudent • Properties • .Count • .HighestStudentGrade

  20. So what is an Object Anyway? • An object may be thought of as simply a word that means something to the computer • The object in this code is MyStudents • Made up by the programmer • Associates the word with the class file clsStudents • Allowing us to access the function/method AddStudent

  21. Instantiation • Stuff in green called comments • Create an object MyCompter referencing the code in the class file clsComputer • Invokes the function/method TurnOff • Instantiation is the act of creating an object

  22. Summary • Programming is the act of writing lists of words that control the data in the system • We need a system for writing lists of instruction for the computer that makes reasonable sense to human beings • We also have some key words for you to start getting to grips with… • Function A function is sequence of words that instruct the computer to perform a single action on some data well • Property A property is a function that tells us about or sets some aspect of the data • Method A method is a function that changes the data in some way • Class A class is a collection of related functions in a text file • Object An object is a word that references the code in the associated class • Instantiation The process of linking an object to a class

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