Application Development with Harbour/Object Oriented Programming

What is object oriented programming?

To understand what object oriented programming is, we need to understand what classes and objects are, and what the differences between them are. You could say that a class is a blueprint to make objects. A metaphor for this is: A map for building a car is the class. The map is not the car itself, but a way to describe how the car should be made. The car with a specific implementation is the object. For example the map for building a car describes characteristics like color, shape/size, weight, and behaviour like steering, switch on/off light.

Here is a class template:

   [CREATE] CLASS <cClassName> [ FROM | INHERIT <cSuperClass1> [, ... ,<cSuperClassN>] ]
             [ MODULE FRIENDLY ] [ STATIC ] [ FUNCTION <cFuncName> ]

   [HIDDEN:]
      [ CLASSDATA | CLASSVAR  | CLASS VAR <DataName1>]
      [ DATA | VAR  <DataName1> [,<DataNameN>] [ AS <type> ] [ INIT <uValue> ]
             [[EXPORTED | VISIBLE] | [PROTECTED] | [HIDDEN]] [READONLY | RO] ]
      ...
      [ METHOD <MethodName>( [<params,...>] ) [CONSTRUCTOR] ]
      [ METHOD <MethodName>( [<params,...>] ) INLINE <Code,...> ]
      [ METHOD <MethodName>( [<params,...>] ) BLOCK  <CodeBlock> ]
      [ METHOD <MethodName>( [<params,...>] ) EXTERN <funcName>([<args,...>]) ]
      [ METHOD <MethodName>( [<params,...>] ) SETGET ]
      [ METHOD <MethodName>( [<params,...>] ) VIRTUAL ]
      [ METHOD <MethodName>( [<params,...>] ) OPERATOR <op> ]
      [ ERROR HANDLER <MethodName>( [<params,...>] ) ]
      [ ON ERROR <MethodName>( [<params,...>] ) ]
      ...
   [PROTECTED:]
      ...
   [VISIBLE:]
   [EXPORTED:]
      ...

   [FRIEND CLASS <ClassName,...>]
   [FRIEND FUNCTION <FuncName,...>]

   [SYNC METHOD <cSyncMethod>]

   ENDCLASS [ LOCK | LOCKED ]