harbour-core/harbour/doc/en/idle.txt

/*
 * $Id$
*/

/*  $DOC$
 *  $TEMPLATE$
 *     Document
 *  $NAME$
 *      The idle states
 *  $CATEGORY$
 *      Document
 *  $ONELINER$
 *      Read me file for Idle States
 *  $DESCRIPTION$
 *      The idle state is the state of the harbour virtual machine when it
 *      waits for the user input from the keyboard or the mouse. The idle
 *      state is entered during INKEY() calls currently. All applications
 *      that don't use INKEY() function call can signal the idle states with
 *      the call of HB_IDLESTATE() function (or hb_idleState() on C level).
 *
 *      During idle states the virtual machine calls the garbage collector and
 *      it can call user defined actions (background tasks). It also releases
 *      the CPU time slices for some poor platforms that are not smart enough
 *      (Windows NT).
 *
 *      For defining the background tasks see the HB_IDLEADD() and HB_IDLEDEL()
 *      functions.
 *
 *      For direct call for background actions see HB_IDLESTATE() function.
 *
 *      For signaling the idle state from C code see the hb_idleState()
 *      API function.
 *  $SEEALSO$
 *      HB_IDLEADD(),HB_IDLEDEL()
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *     Function
 *  $NAME$
 *      HB_IDLEADD()
 *  $CATEGORY$
 *      API
 *  $SUBCATEGORY$
 *      Idle states
 *  $ONELINER$
 *      Adds the background task.
 *  $SYNTAX$
 *      HB_IDLEADD( <bAction> ) --> nHandle
 *  $ARGUMENTS$
 *      <bAction> is a codeblock that will be executed during idle states.
 *      There are no arguments passed to this codeblock during evaluation.
 *  $RETURNS$
 *      <nHandle> The handle (an integer value) that identifies the task. This
 *      handle can be used for deleting the task.
 *  $DESCRIPTION$
 *      HB_IDLEADD() adds a passed codeblock to the list of background
 *      tasks that will be evaluated during the idle states. There is no
 *      limit for the number of tasks.
 *  $EXAMPLES$
 *      nTask := HB_IDLEADD( {|| SayTime() } )
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      Harbour extension similar to FT_ONIDLE() function available
 *      in NanForum library.
 *  $PLATFORMS$
 *      All
 *  $FILES$
 *      src/rtl/idle.c
 *  $SEEALSO$
 *      HB_IDLEDEL(),HB_IDLESTATE()
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *     Function
 *  $NAME$
 *      HB_IDLEDEL()
 *  $CATEGORY$
 *      API
 *  $SUBCATEGORY$
 *      Idle states
 *  $ONELINER$
 *      Removes the background task from the list of tasks.
 *  $SYNTAX$
 *      HB_IDLEDEL( <nHandle> ) --> <bAction>
 *  $ARGUMENTS$
 *      <nHandle> is the identifier of the task returned by the
 *      HB_IDLEADD() function.
 *  $RETURNS$
 *      <bAction> NIL if invalid handle is passed or a codeblock that was
 *      passed to HB_IDLEADD() function
 *  $DESCRIPTION$
 *      HB_IDLEDEL() removes the action associated with passed identifier
 *      from the list of background tasks. The identifer should be the
 *      value returned by the previous call of HB_IDLEADD() function.
 *
 *      If specified task is defined then the codeblock is returned
 *      otherwise the NIL value is returned.
 *  $EXAMPLES$
 *      nTask := HB_IDLEADD( {|| SayTime() } )
 *      INKEY(10)
 *      bAction := HB_IDLEDEL( nTask )
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *      All
 *  $FILES$
 *      src/rtl/idle.c
 *  $SEEALSO$
 *      HB_IDLEADD(),HB_IDLESTATE()
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *     Procedure
 *  $NAME$
 *      HB_IdleState()
 *  $CATEGORY$
 *      API
 *  $SUBCATEGORY$
 *      Idle states
 *  $ONELINER$
 *      Evaluates a single background task and calls the garbage collector.
 *  $SYNTAX$
 *      HB_IDLESTATE()
 *  $ARGUMENTS$
 *      None
 *  $DESCRIPTION$
 *      HB_IDLESTATE() requests the garbage collection and executes a
 *      single background task defined by the codeblock passed with
 *      HB_IDLEADD() function. Every call to this function evaluates a
 *      different task in the order of task creation. There are no
 *      arguments passed during a codeblock evaluation.
 *
 *      This function can be safely called even if there are no background
 *      tasks defined.
 *  $EXAMPLES$
 *      nTask1 := HB_IDLEADD( {|| SayTime() } )
 *      nTask2 := HB_IDLEADD( {|| SaveScreen() } )
 *      DO WHILE( !bFinished )
 *        bFinished := DOSomethingVeryImportant()
 *        HB_IdleState()
 *      ENDDO
 *      cbAction := HB_IDLEDEL( nTask1 )
 *      HB_IDLEDEL( nTask2 )
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      Harbour extension similar to FT_IAMIDLE() function available
 *      in NanForum library.
 *  $PLATFORMS$
 *      All
 *  $FILES$
 *      src/rtl/idle.c
 *  $SEEALSO$
 *      HB_IDLEADD(),HB_IDLEDEL()
 *  $END$
 */

/*  $DOC$
 *  $TEMPLATE$
 *     Procedure
 *  $NAME$
 *      hb_idleState()
 *  $CATEGORY$
 *      C level API
 *  $SUBCATEGORY$
 *      Idle states
 *  $ONELINER$
 *      Evaluates a single background task and calls the garbage collector.
 *  $SYNTAX$
 *      void hb_idleState( void );
 *  $ARGUMENTS$
 *      None
 *  $DESCRIPTION$
 *      hb_idleState() is a C function that requests garbage collection and
 *      executes a single background task defined by the codeblock passed
 *      with HB_IDLEADD() function. It also releases the CPU time slices for
 *      platforms that require it.
 *
 *      Every call for this function evaluates different task in the
 *      order of task creation. There are no arguments passed during
 *      codeblock evaluation.
 *
 *      This function can be safely called even if there are no background
 *      tasks defined.
 *
 *      This function is automatically called from the INKEY() function.
 *  $STATUS$
 *      R
 *  $COMPLIANCE$
 *      H
 *  $PLATFORMS$
 *      All
 *  $FILES$
 *      src/rtl/idle.c
 *  $SEEALSO$
 *      HB_IDLEADD(),HB_IDLEDEL(),HB_IDLESTATE()
 *  $END$
 */