Introduction to Alice

Introduction to Alice Basics: •What is Alice? •Object Oriented Definitions •What Does it Look Like? •Where Can I Use it? What is Alice ?  Alice (http://www.alice.org) is a 3-D Interactive Graphics Programming Environment  Developed at Carnegie Mellon  Alice is built on top of the programming language Python  The goal of the Alice project is to make it easy for novices to develop interesting 3-D environments and to explore the new medium of interactive 3-D graphics  A tool for teaching concepts of fundamental programming:  Objects  Classes  Methods  Events What is Alice ?  Alice is primarily a scripting and prototyping environment for 3-D object behavior  3-D models of objects (e.g., animals and vehicles) populate a virtual world in Alice. By writing simple scripts, Alice users can control object appearance and behavior  Presents Object-Oriented Design  A software design method that models the characteristics of abstract or real objects using classes and objects What is Alice ? The Alice Approach  Uses 3D graphics to engage students  Has a “smart” drag-and-drop editor that prevents syntax errors What is Alice ? Key Alice Features  Makes objects something students can see and relate to  Has a java syntax mode to ease the transition to C++/Java/VB.net What is Alice ? Schools using Alice 2004-2005: • Bucknell University • Carnegie Mellon University • Clemson University • Colorado School of Mines • Community College of Philadelphia • Cornell University • Duke University • Ithaca College • Plymouth State University • Saint Joseph's University • Saint Lawrence College • San Diego State University • University of Colorado • University of Illinois • University of Mississippi • Virginia Tech Object Oriented Definitions Object  Definition: An object is a software bundle of variables and related methods  Object is defined by its properties and its methods/functions  Real-world objects share two characteristics:  State and Behavior • For example, dogs have state (name, color, breed, hungry) and behavior (barking, fetching, and wagging tail) Object Oriented Definitions Object  Software objects are modeled after real-world objects in that they too have state and behavior  A software object maintains its state in one or more variables  A variable is an item of data named by an identifier  A software object implements its behavior with methods  A method is a function (subroutine) associated with an object Object Oriented Definitions Class  Definition: A class is a blueprint that defines the variables and the methods common to all objects of a certain kind  In the real world, you often have many objects of the same kind  For example, your car is just one of many vehicles in the world  This means that car is one of the choices within the vehicle class Object Oriented Definitions Class  Using object-oriented terminology, we say that your car object is an instance of the class of objects known as vehicles  Vehicles have some state (four wheels) and behavior (accelerate, brake) in common.  However, each vehicle's state is independent of and can be different from that of other vehicles Object Oriented Definitions Method  Definition: A method is a piece of code that is exclusively associated either with a class (called class methods) or with an object (called instance methods)  Like a procedure in procedural programming languages, a method usually consists of a sequence of statements to perform an action, a set of input parameters, and possibly an output value of some kind  The purpose of methods is to provide a mechanism for accessing (for both reading and writing) the private data stored in an object or a class Object Oriented Definitions Method  Methods are essentially instruction sets for objects  Consequently, rather than thinking a method is just a sequence of commands, an OO programmer will consider a method to be "an object's way of providing a service" (its "method of doing the job", hence the name)  A method call is thus considered to be a request to an object to perform some task  Method calls are often modeled as a means of passing a message to an object Object Oriented Definitions Method  For Example:  The Drive method for a car would consist of turning left ¼ and moving away for a distance of 10 meters car Methods car.Drive ( ) No variables Do in order car turn left 0.25 revolutions car move forward 10 meters Object Oriented Definitions Event  Definition: An event is an action or occurrence detected by a program  Events can be user actions, such as clicking a mouse button or pressing a key, or system occurrences, such as running out of memory  Most modern applications are said to be event-driven, because they are designed to respond to events What Does it Look Like ? Where Can I Use it ?  Computer Lab  Alice is loaded on the computers in the CCRI Academic Computer Lab  Look for the Alice icon on the desktop or under Programs from the Windows Start Menu  Download •ALICE Programming software - can be downloaded at http://www.alice.org (download the most recent version) •The download is 115 Megabytes so may be difficult if you do not have access to a broadband network.