为什么在我的Delphi对象上没有调用_AddRef和_Release？

Question

我真的很困惑.

// initial class
type
    TTestClass = 
        class( TInterfacedObject)
        end;

{...}

// test procedure
procedure testMF();
var c1, c2 : TTestClass;
begin
    c1 := TTestClass.Create(); // create, addref
    c2 := c1; // addref

    c1 := nil; // refcount - 1

    MessageBox( 0, pchar( inttostr( c2.refcount)), '', 0); // just to see the value
end;

它应该显示1,但它显示0.无论我们将执行多少分配,值都不会改变!为什么不？

Answer 1

只有在分配给接口变量而不是对象变量时,才会修改Refcount.

procedure testMF(); 
var c1, c2 : TTestClass; 
    Intf1, Intf2 : IUnknown;
begin 
    c1 := TTestClass.Create(); // create, does NOT addref
    c2 := c1; // does NOT addref 

    Intf1 := C2;  //Here it does addref
    Intf2 := C1;  //Here, it does AddRef again

    c1 := nil; // Does NOT refcount - 1 
    Intf2 := nil; //Does refcount -1

    MessageBox( 0, pchar( inttostr( c2.refcount)), '', 0); // just to see the value 
    //Now it DOES show Refcount = 1
end;