Functions and Directives

Function ReadVar() Foundation

Determines name of the current GET or MENU TO variable.

Syntax
ReadVar() --> cVariableName
Return

ReadVar() returns the name of the variable in the current GET or MENU TO command as a character string.

Description

The environment function ReadVar() returns the variable name as a character string which was specified in the command GET or MENU TO. The variable name is only returned if one of these two commands were executed. Using ReadVar(), a context sensitive help system can be created based on the name of the variable specified to store the MENU TO result or identified as an input field of a Get.

Examples
Help system with ReadVar()
// The example shows a simple help system based on 
// ReadVar(). When the F1 key is pressed, help text is 
// displayed using MemoEdit() and information stored in 
// a memo file. Depending on the #define constant DEBUG, 
// the help text can be edited or just displayed at runtime. 
// Using this technique, help text can be written at runtime 
// during development of a program while the delivery version 
// of the program only allows help text to be displayed. 

#include "Inkey.ch" 

#define  DEBUG // help texts can be edited at runtime 

PROCEDURE Main 
   LOCAL nMainMenu 
   IF ! File("HELP.DBF") 
      DbCreate("HELP", { { "READVAR" , "C", 10, 0} ,; 
                         { "HELPTEXT", "M", 10, 0} } ) 
      USE HELP NEW EXCLUSIVE 
      INDEX ON Readvar TO HELP 
   ENDIF 

   SET KEY K_F1 TO Help 

   DO WHILE .T. 

      @ 10,10 PROMPT "Customer screen" 
      @ 11,10 PROMPT "Parts screen" 
      MENU TO nMainMenu 

      DO CASE 
      CASE nMainMenu == 0 
         CLOSE ALL 
         EXIT 
      CASE nMainMenu == 1 
         Customers() 
      CASE nMainMenu == 2 
         Parts() 
      ENDCASE 
   ENDDO 

RETURN 

******************* 
PROCEDURE Customers 
   CLS 

   USE Customer NEW 
   @ 10,10 SAY " Last name:" GET Customer->Lastname 
   @ 11,10 SAY "First name:" GET Customer->Firstname 
   READ 

   CLOSE Customer 
RETURN 

*************** 
PROCEDURE Parts 
   CLS 

   USE Parts NEW 
   @ 10,10 SAY "Part No:" GET Parts->PartNo 
   @ 11,10 SAY "   Part:" GET Parts->Part 
   READ 

   CLOSE Parts 
RETURN 

************** 
PROCEDURE Help 
   LOCAL nArea := Select() 

   IF Select("HELP") == 0 
      USE Help INDEX Help NEW 
   ENDIF 

   SELECT Help 
   SEEK Upper( ReadVar() ) 

   IF Found() 
      ShowHelpText( Help->HelpText ) 
   ELSE 
      #ifdef DEBUG 
         APPEND BLANK 
         REPLACE Help->Readvar WITH Upper( ReadVar() ) 
         ShowHelpText( Help->HelpText ) 
      #else 
         ShowHelpText("No help available") 
      #endif 
   ENDIF 
   DbSelectArea( nArea ) 
RETURN 

********************** 
PROCEDURE ShowHelpText( cHelpText ) 
   LOCAL cScreen := SaveScreen( 2, 2, 22,78 ) 

   DispBox(  2, 2,22,78, 2 ) 

   #ifdef DEBUG                    // help texts can be edited 
     REPLACE Help->HelpText WITH ; // in the DEBUG version 
        MemoEdit(cHelpText, 3, 3, 21, 77, .T. ) 
   #else 
     SET CURSOR OFF                // help texts can only be 
                                   // displayed in the 
                                   // delivery version 
     MemoEdit(cHelpText, 3, 3, 21, 77, .F.) 
   #endif 

   RestScreen(2, 2, 22, 78, cScreen) 
   SET CURSOR ON 

RETURN 

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