The Delphi developer who implemented TInterfacedObject obviously
considered the case when an interface reference is grabbed during
construction......
// Set an implicit refcount so that refcounting
// during construction won't destroy the object.
class function TInterfacedObject.NewInstance: TObject;
begin
Result := inherited NewInstance;
TInterfacedObject(Result).FRefCount := 1;
end;
procedure TInterfacedObject.AfterConstruction;
begin
// Release the constructor's implicit refcount
InterlockedDecrement(FRefCount);
end;
but didn't consider applying the same logic during destruction. So
grabing an interface reference during destruction causes all hell to
break loose, as the _Release method tries to free the object again and
again recursively.
procedure TInterfacedObject.BeforeDestruction;
begin
if RefCount <> 0 then
Error(reInvalidPtr);
end;
function TInterfacedObject._Release: Integer;
begin
Result := InterlockedDecrement(FRefCount);
if Result = 0 then
Destroy;
end;
Todd.
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