CALCUDF()
 To get/set the calculator key handler block.
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 Syntax

      CALCUDF( [<bCalcUDF>], [<lAllKeys>] )  -> bOldCalcUDF

 Arguments

      <bCalcUDF> is an optional block parameter containing a code block
      to evaluate upon (0) initialization, (1) operational keys,
      (2) keyboard exceptions, and (3) termination.  DEFAULTS TO NIL.

      <lAllKeys> is an optional logical parameter denoting whether to
      call the code block upon operational keys (i.e. not only keyboard
      exceptions). DEFAULTS TO FALSE.

 Returns

      CALCUDF() returns the current CALCUDF() code block.

 Description

      You may use CALCUDF() to get/set the calculator key handler block.

      Regarding the code block <bCalcUDF> (If it is not NIL):

      . Will be evaluated with 7 parameters:

         . Procedure name (always CALCULATOR)
         . Version number (always 16 in version 1.6)
         . The variable name when the Calculator hotkey was pressed or NIL
         . Numeric representation of the current display
         . Character representation of the current display
         . Numeric mode (0=initialization call, 1=a key was pressed,
             2=key exception, 3=termination)
         . Character representation of the current calculator color
         . Numeric representation of the last key pressed
             (valid for mode #1 and 2 only) (same as LastKey())

      . Will send as the 6th parameter the numeric mode:

         0 = called upon entering the calculator
             (best time to set up your own help screen for your keys)

         2 = called upon a key exception (a key not recognized by
             the calculator operation and no setkey exists)

         3 = called upon exiting the calculator
             (best time to take down your help)

         (If <lAllKeys> is true, then mode 1 will be called,
          else if will not be called):
         1 = called upon any keypress in the calulator,
             prior to executing any operation that the key represents

      . Return Values of the code block

         (The following applies to mode 0, 1, and 2 only - not 3):

         . If your code block returns a TRUE, the calcuator will immediately
           return without further processing.

         . If your code block returns a NUMERIC, the calculator will
           display the numeric as the last result of the calculator.

         . If your code block returns a CHARACTER, it will be "keyboarded"
           into the calculator as if the user had typed it him/herself
           (Be aware of the current SET TYPEAHEAD).

         . Any other data type will be ignored and processing will
           continue normally.

 Examples

     ** Example

        Function Test()

        //Sets the UDF to call during the calculator
        // but (.F.) do not call with ALL keys
        bOldUDF := CALCUDF( {|x1,x2,x3,x4,x5,x6,x7,x8| ;
                    MyCalcUDF(x1,x2,x3,x4,x5,x6,x7,x8) } , .F. )

        Calculator()

        RETURN NIL


        Function MyCalcUDF(cProc,nVer,cVar,nValue,cValue,nMode,cColor,nKey)
        Local xRetCode := .F.  //continue normally

           Do Case
              Case nMode = 0   //Initialization call
                 //put up extra help menu for *MY* keys & save screen

              Case nMode = 3   //Termination call
                 //take down my help screen

              Case nMode = 2   //Key Exception call
                 Do Case
                    Case nKey == K_ALT_F2     //my Square Root
                       xRetCode := SQRT(nValue)

                    Case nKey == K_ALT_T      //my add tax key!
                       xRetCode := nValue * 1.0775

                    Case nKey == "~"          //my sign reverse key!
                       xRetCode := -nValue

                    Case nKey == K_ALT_M      //my memory counter key!
                       CalcMemory( CalcMemory()+1 )

                 Endcase

           Endcase

        Return xRetCode

     -----------------------------------------------------------------------
     . NOTE

     (When initially entering the calculator, or during keyboard calls):

         . If your code block returns a TRUE, it will immediately
           abandon the calculator without further processing.

         . If your code block returns a NUMERIC, the calculator will
           display the numeric as the last result of the calculator.

         . If your code block returns a CHARACTER, it will be "keyboarded"
           into the calculator as if the user had typed it him/herself
           (Be aware of the current SET TYPEAHEAD).

         . Any other data type will be ignored and processing will
           continue normally.

     This NOTE does not apply to the call when exiting the calculator.
     -----------------------------------------------------------------------


 Files: CALC.LIB

 Author: Touchstone Business Creations          CompuServe ID: 73670,2561
         28613 River Glen Ct. #1
         Menifee, CA 92584-8987 USA

         (909) 679-3364

 Owner : (c) Copyright, 1991,92,93 Touchstone Business Creations