Procedure

   void chkout_c ( ConstSpiceChar  * module )

Abstract

   Inform the CSPICE error handling mechanism of exit from a
   routine.

Required_Reading

   ERROR

Keywords

   ERROR

Brief_I/O

   VARIABLE  I/O  DESCRIPTION
   --------  ---  --------------------------------------------------
   module     I   The name of the calling routine.

Detailed_Input

   module         is the name of the routine calling chkout_c.  The
                  named routine is supposed to be `checking out'
                  when it calls chkout_c; that is, the call should be
                  the last executable statement preceding any exit
                  from the routine.

Detailed_Output

   None.

Parameters

   None.

Exceptions

   chkout_c does not signal errors; rather it writes error messages,
   so as to avoid recursion.

   1)  If the input module name module does not match the name popped
       from the trace stack, the short error message
       SPICE(NAMESDONOTMATCH) is written to the error output device.

   2)  If the trace stack is empty, the short error message
       SPICE(TRACESTACKEMPTY) is written to the error output device.

Files

   None.

Particulars

   This routine is part of the CSPICE error handling mechanism.

   Conceptually, the effect of this routine is to `pop' a module
   name from a stack.  The routine chkin_c performs the inverse, or
   `push' operation.

   Every routine that participates in the traceback scheme should
   have a call to chkin_c as the second executable statement.
   The first executable statements should be:

      if ( return_c() )
         {
         return;
         }
      else
         {
         chkin_c ( module );
         }


   Here module is the name of the routine in which this code appears.

   The line of code preceding the exit or any return statement
   should be

      chkout_c  ( module );

   All CSPICE routines should call chkin_c and chkout_c, unless they
   are classified as `error free'.  Programs linked with CSPICE
   may also use chkin_c and chkout_c.

   Routines that don't call chkin_c and chkout_c won't appear in the
   traceback.

   All routines that call chkin_c must also call chkout_c, or else the
   trace mechanism will become very confused and need alot of therapy.

   It is possible to disable check-ins (and check-outs) by calling
   the trcoff_c.  chkin_c and chkout_c will return immediately
   upon entry after trcoff_c has been called.  It is not possible to
   re-enable check-ins and check-outs after calling trcoff_c. Routines
   that don't call chkin_c and chkout_c won't appear in the traceback.

Examples

   1)  Call chkout_c before a return statement:

          if ( failed() )
             {
             chkout_c ( module );
             return;
             }


   2)  Call chkout_c before an exit statement:

          chkout_c ( module );
          exit;


   3)  Only ONE call to chkout_c is needed here:

          chkout_c ( module ) ;
          return;

Restrictions

   Routines that call this routine must call chkin_c as the second
   executable statement. (The first is a call to return_c() ).

Literature_References

   None.

Author_and_Institution

   N.J. Bachman    (JPL)
   K.R. Gehringer  (JPL)

Version

   -CSPICE Version 2.0.1, 08-FEB-1998 (EDW)

      Corrected and clarified header entries.

   -CSPICE Version 2.0.0, 09-JAN-1998 (NJB)

      Input argument filename was changed to type ConstSpiceChar *.

      Re-implemented routine without dynamically allocated, temporary
      strings.

   -CSPICE Version 1.0.0, 25-OCT-1997 (EDW)

Index_Entries

   module check out

Link to routine chkout_c source file chkout_c.c