3.3.6 High level programming paradigms

Programming paradigms
1. In a computing context it means ways of programming.
2. Paradigm means an example or pattern.
3. Different languages may use different paradigms.
4. Some languages may be designed to use one or many paradigms.
Low-level languages
1. First languages created were these kinds of languages
2. One to one relationship with machine code
Procedural Languages
1. Programmer states steps needed to execute program
2. Programmers decide the steps and order that the program needs to follow
3. Program divided into blocks of code called functions and procedures.
4. Procedures have their own variables that can not be accessed outside of them.
5. Logic of the program expressed via procedure calls.
6. Languages include: Pascal, C, Visual Basic
Object-Orientated
1. Programmer designs self-contained objects.
2. Objects contain both program routines and the data being processed.
3. Program is split into objects which can be used by other objects to build a more complex system.
4. Objects are self-contained and simple and so are easier to program.
5. Objects can be reused and inherited without having to rewrite code.
6. Languages include: C++, Delphi, Java, Visual Basic
7. Object has three main sections
  1. 1: Name: The name of the class
  2. 2: Data: Information that all objects of this type have (all students go to school, so school would be a data field inside of the class student).
  3. 3: Methods: Bits of code that allow you to access and modify the data inside of the object.
    1. Data inside of an object can only be accessed by using the methods provided inside of the object. This is referred to as data encapsulation. Data encapsulation makes it more difficult to write faulty code that overwrites data incorrectly.
8. Inheritance
  1. One class can inherit the properties of another class. The employee class may inherit the person class, meaning employee objects does not have to rewrite code that deals with the name or age of a person.
  2. If X is a class that is inherited by another class then it is referred to as a super class.
  3. If X is a class that inherits from another class then it is referred to as being derived from the super class.
9. Unified Modeling Language
  1. UML consists of a set of diagrams which are used to help plan and design the structure of a program using OOP.
  2. There are several different diagrams that are a part of UML. We have to know 7 of these.
  3. Class Diagrams
    2. Name of the class
    3. The facts (variables) that need to be known about any element belonging to the class and the data structure that will be used.
    4. The methods in the class that are used to access the facts (variables) inside of the class.
  4. Object Diagrams
    3. A specific student in the class student is referred to as an object. An object diagram therefore shows an individual students attributes
    4. This object diagrams refers to any member of the student class. It is referred to as an anonymous object
  5. Use Case Diagrams
    2. Use case diagrams show what is going into a system rather than how they work. The actors have control over the processes. These are generally more business oriented diagrams than programming related diagrams however they can help set the ground work.
  6. State Diagrams
    2. State diagrams show how an object behaves through the various processes of a system. It starts with the initial circle to show the initial state. The arrows show the flow of activity from state to state. State transitions occur when a trigger occurs (such as the process find facts). The end of the system is shown by end points (a circle with a dot in) which are the red dots in the diagram above.
  7. Sequence Diagrams
    2. Sequence diagrams show how different classes interact with each other. At the top of the diagram are the classes. The dotted lines below the classes shows how long a class can be seen to be active, this is referred to as the lifeline of a class. The long thin boxes are where the are where the methods of the class have been activated to do something.
  8. Activity Diagrams
    3. Activity diagrams shows the activities needed to get an object to a particular state. In the exam the diagram will always have keys and so you don't have to remember the specifics of what symbols means what, you just have to be confident you can follow the logic.
  9. Communication Diagrams
    2. Communication diagrams show how classes interact with each other and the order that they interact with each other and the methods that they use to call each other.
Declarative
1. Program consists of a set of declarations.
2. Describes what computation should be performed and not how to do it.
3. A language with clear correspondence to mathematical logic.
4. Languages include: HTML, CSS, SVG
5. Given a set of facts and a set of rules.
  1. Facts: Fruit(Cherry), Fruit(Strawberry), Vegetable(Parsnip), Vegetable(Carrot), Favourites(Strawberry), Favourites(Carrot)
  2. Rule: Fruit(X)
    1. Returns Cherry and Starwberry
  3. Rule: Fruit(X), Favourites(X)
    1. Returns Strawberry (as Cherry is not in favourites and Carrot is not in fruit)
    2. Example of Predicate Logic. In order for statement to be true it predicates both individual statements to be true.

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3.3.6 High level programming paradigms

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	Created by Adam Cook over 8 years ago