The following code shows a summary of the main clauses:

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DEFINE CLASS Clause [Property_Definition_Clause] [PEMName_COMATTRIB Clause] [ADD OBJECT Clause] [IMPLEMENTS Clause] [Function_Procedure_Definition_Clause] ENDDEFINE

The following sections describe detailed syntax and parameters for each clause of the DEFINE CLASS command:

• DEFINE CLASS Command - DEFINE CLASS Clause
  
  
• DEFINE CLASS Command - Property Definition Clause
  
  
• DEFINE CLASS Command - PEMName_COMATTRIB Clause
  
  
• DEFINE CLASS Command - ADD OBJECT Clause
  
  
• DEFINE CLASS Command - IMPLEMENTS Clause
  
  
• DEFINE CLASS Command - Function or Procedure Definition Clause
  
  

Code for user-defined classes is stored in a program (.prg) file, similar to procedures.

Note:
You cannot follow procedures in a .prg file with normal executable program code. Only class definitions, other procedures, and user-defined functions can follow the first DEFINE CLASS, PROCEDURE or FUNCTION statement in the file. For more information, see User-Defined Procedures and Functions.

You cannot place class definitions created with DEFINE CLASS within structured programming commands, for example, IFВ ...В ENDIF or DO CASEВ ...В ENDCASE, or in loops, such as DO WHILEВ ...В ENDDO or FORВ ...В ENDFOR.

To instantiate, or create instances of, the class you defined, use the CREATEOBJECT(В ) function. You can access public properties and call method and event functions and procedures outside the class definition as shown in the following example:

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myObject = CREATEOBJECT('MyClass') myObject.myPropertyName = myObject.myMethodName( argument1, argument2, ... ) myObject.myEventName

Protected or hidden properties, methods, and events have restricted access as defined by the PROTECTED and HIDDEN keywords. For more information, see DEFINE CLASS Command - Property Definition Clause and DEFINE CLASS Command - Function or Procedure Definition Clause.

Visual FoxPro converts ASВ Type clause values automatically when other COM servers use them. When you type the AS clause in code, IntelliSense functionality in Visual FoxPro displays the type information for COM servers.

The following table shows the data type information that is displayed.

You can view code for Access and Assign methods in the Trace window of the Debugger window. However, you cannot execute Access and Assign methods from the Watch and Local windows of the Debugger window. For more information, see Access and Assign Methods, Trace Window, and Debugger Window.

A safe array is a one- or multi-dimensional array of a single data type, which can be of type VARIANT, allowing you to create arrays of mixed types. The safe array stores its lower bound, which does not have to be zero, and its size. Safe arrays allow locking and unlocking so you can be sure that the pointer you receive to the data is valid.

The following example creates a class named MyForm from the Form base class and adds a command button from the CommandButton base class and a check box from the CheckBox base class:

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DEFINE CLASS MyForm AS Form ADD OBJECT cmdButton1 AS CommandButton ADD OBJECT chkBox1 AS CheckBox ENDDEFINE

As another example, the following code creates a class called MyForm, adds a command button and check box to the class, and specifies values for the Caption properties of the command button and check box.

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DEFINE CLASS MyForm AS Form ADD OBJECT cmdButton1 AS CommandButton WITH Caption = "Yes" ADD OBJECT chkBox1 AS CheckBox WITH Caption = "Click Me" ENDDEFINE