harbour-core/doc/en/hb_set.txt

/*
 * The following parts are Copyright of the individual authors.
 * www - http://harbour-project.org
 *
 * Copyright 1999 David G. Holm <dholm@jsd-llc.com>
 *   Header file for the API
 *
 * See COPYING.txt for licensing terms.
 *
 */

/* $DOC$
   $TEMPLATE$
      Function
   $NAME$
      hb_setListenerAdd()
   $CATEGORY$
      C level API
   $SUBCATEGORY$
      Environment
   $ONELINER$

   $SYNTAX$
      C Prototype

      #include "hbset.h"
      hb_setListenerAdd( PHB_SET_LISTENER_CALLBACK callback ) --> int
   $ARGUMENTS$
      <callback>
      A pointer to a function taking two enum parameters and returning
      no value. The first parameter identifies the SET parameter that is
      to be changed and the second parameter identifies whether the call
      is from before or after the value is changed. The callback function
      will be called twice whenever a SET parameter is changed using the
      Harbour SET function. The first call takes place before the SET
      value is changed and the second one is after the SET parameter has
      been changed.
   $RETURNS$
      An integer value representing the callback handle, in case the
      caller needs to deactivate the callback function.
   $DESCRIPTION$
      This function allows a subsystem that needs to track the status
      of some SET parameters to be notified whenever a SET parameter gets
      changed.
   $EXAMPLES$
      void callback_function( HB_set_enum set, HB_set_listener_enum when )
      {
         printf("\nCalled for SET parameter %d %s changing.",
            set, (when ? "after" : "before"));
      }
      int handle = hb_setListenerAdd( callback_function );
   $STATUS$
      R
   $COMPLIANCE$
      NA
   $FILES$
      Library is core
   $PLATFORMS$
      All
   $SEEALSO$
      hb_setListenerRemove()
   $END$
 */

/* $DOC$
   $TEMPLATE$
      Function
   $NAME$
      hb_setListenerNotify()
   $CATEGORY$
      C level API
   $SUBCATEGORY$
      Environment
   $ONELINER$

   $SYNTAX$
      C Prototype

      #include "hbset.h"
      hb_setListenerNotify( HB_set_enum set, HB_set_listener_enum
      when ) --> int
   $ARGUMENTS$
      <set>
      The number of the SET parameter that is to be or was changed.

      <when>
      Set to HB_SET_LISTENER_BEFORE when called before the SET parameter
      is to be changed and set to HB_SET_LISTENER_AFTER when called
      after the SET parameter has been changed.
   $RETURNS$
      <int>
   $DESCRIPTION$
      This function notifies all SET listener callback functions. It
      must be called any time you change the value of a SET parameter
      directly instead of using the Harbour SET function. Both before
      and after the change.
   $EXAMPLES$
      hb_setListenerNotify( HB_SET_DECIMALS, HB_SET_LISTENER_BEFORE );
      hb_set.HB_SET_DECIMALS = 3;
      hb_setListenerNotify( HB_SET_DECIMALS, HB_SET_LISTENER_AFTER );
   $STATUS$
      R
   $COMPLIANCE$
      NA
   $FILES$
      Library is core
   $PLATFORMS$
      All
   $SEEALSO$
      hb_setListenerAdd()
   $END$
 */

/* $DOC$
   $TEMPLATE$
      Function
   $NAME$
      hb_setListenerRemove()
   $CATEGORY$
      C level API
   $SUBCATEGORY$
      Environment
   $ONELINER$

   $SYNTAX$
      C Prototype

      #include "hbset.h"
      hb_setListenerRemove( int handle ) --> int
   $ARGUMENTS$
      <handle>
      The handle for the SET listener callback function to be removed.
   $RETURNS$
      The handle if the callback function could not be located or the
      negative value of the handle if the callback function was removed.
   $DESCRIPTION$
      This function removes a SET listener callback function.
   $EXAMPLES$
      int handle = hb_setListenerAdd( callback_function );
      ...
      hb_setListenerRemove( handle );
   $STATUS$
      R
   $COMPLIANCE$
      NA
   $FILES$
      Library is core
   $PLATFORMS$
      All
   $SEEALSO$
      hb_setListenerAdd()
   $END$
 */