xHarbour Reference Documentation > Statement Reference

VAR

Declares an instance variable of a class.

Syntax

VAR <MemberName> [ INIT <expression> ] ;
                 [ READONLY ] [ PERSISTENT ]

VAR <MessageName> IN     <SuperClass>
VAR <MessageName> IS     <MemberName> IN <SuperClass>

VAR <MessageName> TO     <ContainedObject>   
VAR <MessageName> IS     <MemberName> TO <ContainedObject>

Arguments

<MemberName>

This is the symbolic name of the instance variable to declare. It must begin with a letter or underscore followed by digits, letters or underscores. The symbolic name can contain up to 63 characters.

INIT <expression>

This is the expression which is executed when an object is created. The return value of <expression> is assigned to <MemberName>.

READONLY

This option declares an instance variable as read only. I.e. when the object exists outside the declaring PRG module, no value can be assigned to <MemberName>. The value of <MemberName> can be changed within methods of the class.

PERSISTENT

This option specifies that the value assigned to <MemberName> is persistent. When an object is serialized with HB_Serialize() and later restored with HB_Deserialize(), the value of <MemberName> is also restored. All instance variables not declared as PERSISTENT are initialized with NIL when a serialized object is restored from its character representation.

<MessageName>

This is the symbolic name of an alternative message to declare for the class.

IN <SuperClass>

Optionally, the name of the super class can be specified to which the message should be sent. This requires the class to inherit one or more other classes.

IS <MemberName>

When a message should be directed to a super class, the member variable to access in the super class can be specified with <MemberName>.

TO <ContainedObject>

This is the symbolic name of an instance variable holding the object that whose instance variable is accessed.

Description

The VAR statement can only be used in the class declaration between CLASS and ENDCLASS. It declares the symbolic name of an instance variable. This name must be sent to an object to access the instance variable.

VAR is more versatile than the DATA declaration, since it allows for declaring message delegation to contained objects or super classes. Refer to DATA for more information on instance variable declaration.

Info

See also:	CLASS, DATA, EXPORTED:, HBObject()
Category:	Class declaration , Declaration , xHarbour extensions
Header:	hbclass.ch
Source:	vm\classes.c
LIB:	xhb.lib
DLL:	xhbdll.dll