Difference between revisions of "CLASS - Properties"
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Revision as of 09:47, 2 June 2009
Contents
Class
Objects
Purpose
Create properties in a user-defined class
Syntax
PROPERTY <memvar> | <array> | <dynamic array> [, ...]
[AS CHARACTER | NUMERIC | LOGICAL | DATE | <class>] [, ...]
See Also
ADDPROPERTY(), CLASS, CLASS - Methods, CLASS - Parameters, CLASS - Scoping, CREATEOBJECT(), DEFINE CLASS, DODEFAULT(), LOCAL, METHOD, NEWOBJECT(), PRIVATE, PUBLIC, REMOVEPROPERTY(), STATIC
Description
The PROPERTY command is used inside the CLASS...ENDCLASS construct to define properties of a class. The PROPERTY command can create memory variables, arrays, and dynamic arrays. You reference properties in an object using the dot (.) member access operator. The full syntax is <object>.<property>.
The visibility of the properties of an object is governed by their scope. Unless otherwise specified, all properties defined within a class are public.
<memvar> | <array> | <dynamic array>
The property name is either a memory variable name <memvar>, or an array name <array>. Arrays are defined with the "arrayname[<expN>]" construct. The <expN> represents the number of array elements, if the number is not specified then the array is defined dynamic.
AS CHARACTER | NUMERIC | LOGICAL | DATE
The data type of values assigned to a property within an object can be checked at run-time by associating a data type with the property in the class definition. The AS clause is used to perform data scoping. Once a variable has been defined as a specific data type, you cannot change its data type by assigning it a value from a different data type: doing this will result in the run-time error "Data type mismatch".
AS <class name>
A property data type can inherit a class <class name>, and its members and their implementation from another class. Inheritance enables developers to build a hierarchy of descendant objects. The specification of a property data type as an existing class name provides for construction of a class hierarchy. The inheriting class is called a derived class, and the class that the derived class inherits is called a base class.
Example
// Example of Properties class Company property cCOMPANY_NAME as character property cCOMPANY_CODE as character property aADDRESS[] property cCOUNTRY as character property cWWW property cTEL property cFAX endclass oCOMPANY = new Company() oCOMPANY.cCOMPANY_NAME = [Recital Corporation Inc] oCOMPANY.aADDRESS.line1 = [85 Constitution Lane] oCOMPANY.aADDRESS.line2 = [Danvers] oCOMPANY.aADDRESS.line3 = [MA 01923] oCOMPANY.cWWW = [http:/www.recital.com] display memory
Products
Recital Database Server, Recital Mirage Server, Recital Terminal Developer