IO_UserHook                                                      IOTTT



NOTE This is not a procedure. IO_UserHook is declared as a pointer
     variable.

Purpose   To provide a way of intercepting the input and optionally
          calling a non-Toolkit procedure, i.e. a special procedure
          you have written.

Type Optional

Declaration    IO_UserHook := @Procedure_Name

          Procedure_name is the actual name of the procedure which is
          to be called each time a key is pressed.

Uses CRT, FastTTT, DOS, WinTTT, KeyTTT, IOTTT.

Remarks   The procedure must be declared as follows:


Example        {$F+}
               PROCEDURE_NAME(CH:CHAR; FIELDID: INTEGER; VAR RETURNSTR:
               STRING);
               BEGIN
               .....   {STATEMENTS}
               END;
               {$F-}


The compiler directives (F and F-) designate the procedure as
FAR. The Procedure_Name can be any valid procedure name, and
this procedure may call other procedures. The 3 procedure
parameters must be defined in the order shown.

Ch will be the value of the character input by the user
,refer to appendix B for a list of the codes. Check this
variable immediately and EXIT the procedure if it is not one
of the special keys you are trying to intercept.

FieldID will indicate the ID of the field the user is
currently editing.

ReturnStr is passed to the procedure with the current field
value. You may update this variable to reset the current
value of the field.

Example   See IOdem.pas on the distribution disk.