JCL中由接口获得对象的方法

ruilin215

我原本并不想单独发以下JCL的方法，可是想到很多人可能还是不知道的。另外，从我博客的回复上看，很多人也愿意去了解一下，特此贴出JCL中的代码。
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<blockquote><span style=""><span class="pas1-comment"><div style="padding-right: 5.4pt; padding-left: 5.4pt; background: #e6e6e6; padding-bottom: 4px; width: 95%; padding-top: 4px;">//===Interfaceinformation==================================================

functionGetImplementorOfInterface(constI:IInterface):TObject;
...{TODO-cDOC:OriginalcodebyHallvardVassbotn}
...{TODO-cTesting:Checktheimplemetationforanyfurtherversionofcompiler}
const
AddByte=$04244483;//opcodeforADDDWORDPTR[ESP+4],Shortint
AddLong=$04244481;//opcodeforADDDWORDPTR[ESP+4],Longint
type
PAdjustSelfThunk=^TAdjustSelfThunk;
TAdjustSelfThunk=packedrecord
caseAddInstruction:Longintof
AddByte:(AdjustmentByte:ShortInt);
AddLong:(AdjustmentLong:Longint);
end;
PInterfaceMT=^TInterfaceMT;
TInterfaceMT=packedrecord
QueryInterfaceThunk:PAdjustSelfThunk;
end;
TInterfaceRef=^PInterfaceMT;
var
QueryInterfaceThunk:PAdjustSelfThunk;
begin
try
Result:=Pointer(I);
ifAssigned(Result)then
begin
QueryInterfaceThunk:=TInterfaceRef(I)^.QueryInterfaceThunk;
caseQueryInterfaceThunk.AddInstructionof
AddByte:
Inc(PChar(Result),QueryInterfaceThunk.AdjustmentByte);
AddLong:
Inc(PChar(Result),QueryInterfaceThunk.AdjustmentLong);
else
Result:=nil;
end;
end;
except
Result:=nil;
end;
end;