JCL中由接口获得对象的方法

//=== Interface information ==================================================

function GetImplementorOfInterface(const I: IInterface): TObject;
{ TODO -cDOC : Original code by Hallvard Vassbotn }
{ TODO -cTesting : Check the implemetation for any further version of compiler }
const
AddByte = $04244483; // opcode for ADD DWORD PTR [ESP+4], Shortint
AddLong = $04244481; // opcode for ADD DWORD PTR [ESP+4], Longint
type
PAdjustSelfThunk = ^TAdjustSelfThunk;
TAdjustSelfThunk = packed record
case AddInstruction: Longint of
AddByte: (AdjustmentByte: ShortInt);
AddLong: (AdjustmentLong: Longint);
end;
PInterfaceMT = ^TInterfaceMT;
TInterfaceMT = packed record
QueryInterfaceThunk: PAdjustSelfThunk;
end;
TInterfaceRef = ^PInterfaceMT;
var
QueryInterfaceThunk: PAdjustSelfThunk;
begin
try
Result := Pointer(I);
if Assigned(Result) then
begin
QueryInterfaceThunk := TInterfaceRef(I)^.QueryInterfaceThunk;
case QueryInterfaceThunk.AddInstruction of
AddByte:
Inc(PChar(Result), QueryInterfaceThunk.AdjustmentByte);
AddLong:
Inc(PChar(Result), QueryInterfaceThunk.AdjustmentLong);
else
Result := nil;
end;
end;
except
Result := nil;
end;
end;