Writing Excel Addons - Xloper Definition

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TVal = packed Record
           Case Byte of
           1: (num: Double); (* xltypeNum *)
           2: (str: ^ShortString); (* xltypeStr *)
           3: (bool: Word); (* xltypeBool *)
           4: (err: Word); (* xltypeErr *)
           5: (w: Integer); (* xltypeInt *)
           6: (sref : packed record
                 count:word;
                 ref: Xlref;
               end);
           8: (_array : packed Record (* xltypeMulti *)
                         lparray: LPXLOPERArray;
                         rows: WORD;
                         columns: WORD;
                       End);
           9: (mref : packed record // xltyperef
                         lpmref : lpxlmref;
                         idsheet : integer;
                       End);
          End; // tval

  XlOper = packed Record
             val: TVal;
             xltype: WORD;
             dummy:array[0..5] of byte; // pads to 16 byte size
           End;
lpxloper = ^xloper;

Problem with Excel calls

From Delphi the big stumbling block with add-ins is the extra parameter after the return address on the stack. This comes free with every call to Excel. I’ve never found out what it holds, but so long as you throw it away, your add-in will work fine. Add the line asm pop variable, end; after every call where variable can be any global, local or object variable that is at least 4 bytes long- integer is fine. To repeat- THIS MUST BE INCLUDED after every Excel4v call. Otherwise you are constructing a time-bomb.

Example

Eresult:= Excel4V(xlfCaller,@xres,0,[nil]);
asm pop sink; end; // Never Remove

Note that with Delphi syntax, if xres is an xloper, you can use @xres to define an lpxloper.

Next: Caution- Recalculation Alert! >>
 

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