仅关闭一小部分代码的Delphi范围检查

Unit1;

//here's range checking on or off as per the project setting

code here...

{$R-}

//range checking is off here because the code causes range check errors

code here...

//now I want to revert to the project setting. How do I do that?

code here...

end.

{$IFOPT R+}
  {$DEFINE RANGEON}
  {$R-}
{$ELSE}
  {$UNDEF RANGEON}
{$ENDIF}
//range checking is off here because the code causes range check errors
//code here...
{$IFDEF RANGEON}
  {$R+}
  {$UNDEF RANGEON}
{$ENDIF}

$R

{$R-} // disable range checking
// do non-range-checked operations here
{$R+} // turn range checking back on