1 / 10

Object Oriented Design and Classes

Learn about classes, methods, constructors, objects, and how to organize programs in the context of OOD. Understand data manipulation, accessors, mutators, and object composition with practical examples like the bank account and employee classes.

tennillec
Download Presentation

Object Oriented Design and Classes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Object Oriented Design and Classes

  2. What is a class? • Programming mechanism to support OOD • Data and the methods that operate on that data – collectively called members • Example: bank account class • Provide structure for organizing programs

  3. Methods • Methods operate on data • accessors – read data, provide access to data but do not change it • mutators – change data • examples from bank account, zoo • constructor – builds a new object • An object in an instance of a class • class is a blueprint for objects

  4. BankAccount Class class BankAccount: def __init__(self, initial_balance): self.balance = initial_balance def deposit(self, amount): self.balance += amount def withdraw(self, amount): self.balance -= amount def checkBalance(self): print "Balance: ", self.balance

  5. BankAccount Class def __init__(self, initial_balance): self.balance = initial_balance • __init__ method is the constructor • Used to initialize members of the object • First parameter is self – the object on which the method/constructor is called • Use dot notation (.) to reference members of the object

  6. BankAccount Class def deposit(self, amount): self.balance += amount def withdraw(self, amount): self.balance -= amount • Deposit and withdraw are mutators • they modify the data member balance • First parameter is self • Like functions, methods can take any number of parameters

  7. BankAccount Class def checkBalance(self): print "Balance: ", self.balance • checkBalance does not modify data members

  8. Creating and Using Objects b = BankAccount(500) //Name = Type(constructor parameters)

  9. Creating and Using Objects b = BankAccount(500) //Name = Type(constructor parameters) //how would you withdraw funds? b.withdraw(500) //object_name.method_name(params)

  10. Composing Objects • An object can have a reference to another object class Name: def __init__(self, first, last): self.first = first self.last = last def printName(self): print "Name: ", self.first, " ", self.last class Employee: def __init__(self, first, last, pay): self.name = Name(first, last) self.pay = pay def printEmployee(self): self.name.printName() print "\tPay rate: ", self.pay

More Related