Reference Count mode (reference number)
origin
The Reference Count mode is a relatively simple, but the practicability is very practical. For example, the reference in COM is the foundation of the COM lifecycle control.
purpose
Use the REFERENCE COUNT mode to control the life cycle of the object. The objects will be available in the reference count, otherwise the object will desire to itself.
motivation
The foundation of the Reference Count mode is very similar to the foundation of the Lock. The only difference is that the LOCK is predefined, fixed. Its specific class is also similar to the LOCK mode. Reference Count Mode Default A Behavioral Method: SetReferenced, you can create your own habits when you use some modes. Such as
The Reference Count mode has a better application in Singleton mode.
application
Unit ReferenceCount;
TrefcountSample = Class (TOBJECT)
Private
Freerencecnt: integer;
protected
Function Reference: Boolean;
Procedure setReferenced (IsReference: Boolean);
public
Procedure addReference;
Procedure RemoveReference;
END;
{
*********************************************************** ************
}
Procedure Trefcountsample.addReference;
Begin
INC (freerencecnt);
If Freferencecnt = 1 Then SetReference (TRUE);
END;
Function Trefcountsample.referenced: Boolean;
Begin
RESULT: = (freerencecnt <> 0);
END;
Procedure trefcountsample.removereference;
Begin
Dec (freerencecnt);
If freferencecnt = 0 THEN SETREFERENCED (FALSE);
END;
Procedure Trefcountsample.setrEference (IsReference: Boolean);
Begin
IF NOT REFERENCED THEN FREE
END;
Delphi Example: IUNKNOWN
Iunknown = interface
['{00000000-0000-0000-C000-000000000046}']
...
Function QueryInterface (Const IID: Tguid; Out Obj): hResult; stdcall;
Function _addref: integer; stdcall;
Function _Release: integer; stdcall;
END;
