[vc_row][vc_column][vc_toggle title=”Object:”]A collection of data which represents something, and contains information or data about the object.<\/p>\n
It can also have methods<\/em> (see Methods) which can manipulate the objects’ data<\/p>\n Example:<\/p>\n A car=><\/p>\n A car has properties<\/em> (see properties) and DriveCar() is a method <\/em>operating on the car.<\/p>\n Here, Make, Colour and Engine size are constant <\/em>but Engine revs is variable as you DriveCar().[\/vc_toggle][\/vc_column][\/vc_row][vc_row][vc_column][vc_toggle title=”Method:”]A function<\/em> (see Functions) contained within an object which can alter values of the object.<\/p>\n Example:<\/p>\n A car=><\/p>\n A car has properties<\/em> (see properties) and DriveCar() is a method <\/em>operating on the car.<\/p>\n Here, Make is a constant <\/em>but Engine revs is variable as you DriveCar().<\/p>\n Colour and EngineSize are usually constant once a car is made, but can be changed if need be.<\/p>\n These are often called PseudoConstants.<\/em>[\/vc_toggle][\/vc_column][\/vc_row][vc_row][vc_column][vc_toggle title=”Function:”]A routine which performs and operation on data and can return the result.<\/p>\n A general function may look like this: myfunction( x, y){ return x*y}<\/p>\n Example: function area( width,height){ return width * height}<\/p>\n And to use it: mysquare=area( 30, 40)<\/p>\n So mysquare now equals 1200\u00a0 (30*40)<\/em><\/p>\n In the car example we have a Method called DriveCar(): this is an internal function <\/em>which does not return anything.<\/p>\n We could have another method function which returns a value: lets add a method GetRevs() <\/em>and define it as returning the engine revs.<\/p>\n GetRevs(){ return EngineRevs)<\/p>\n MyCar=><\/p>\n So now when we use the new function we will be told EngineRevs:<\/p>\n currentRevs=MyCar=>GetRevs()<\/p>\n currentRevs=10,000 rpm<\/p>\n Functions can also take Arguments <\/em>(see Arguments), so for example we could define DriveCar to take a speed:<\/p>\n MyCar=>DriveCar( speed )<\/p>\n So we have:<\/p>\n MyCar=><\/p>\n And to set car speed we use it thus:<\/p>\n MyCar=> DriveCar( 50 )<\/p>\n [\/vc_toggle][\/vc_column][\/vc_row][vc_row][vc_column][vc_toggle title=”Variables and Constants:”]A user defined data type which can hold the results of functions or preset value.<\/p>\n In the Car example we have 2 variables <\/em> Colour and EngineSize. These are both things which a car owner can change or vary.<\/em><\/p>\n The Car Make is not changeable by the owner once it has been made, so Make is considered a Constant.<\/em><\/p>\n MyCar=><\/p>\n These are all attributes of the car.<\/p>\n (Note properties and attributes terms are often used interchangeably)[\/vc_toggle][\/vc_column][\/vc_row][vc_row][vc_column][vc_toggle title=”Attribute:”]A property of an object which holds a value.<\/p>\n Example:<\/p>\n MyCar=><\/p>\n These are all attributes of the car.<\/p>\n (Note properties and attributes terms are often used interchangeably)[\/vc_toggle][\/vc_column][\/vc_row][vc_row][vc_column][vc_toggle title=”Constructor:”]A collection of attributes which instruct object creation.<\/p>\n To create a car you need to have a Car template or Class, <\/em>then to construct <\/em> a new Car you can use the basic default Car class and modify it as it is constructed.<\/p>\n Example:<\/p>\n MyNewCar= new Car( Colour=Red, Engine_size=1500, Make=Ford )<\/p>\n So the new car will look like this:<\/p>\n MyNewCar=><\/p>\n\n
\n
\n
\n
\n
\n