The DAT_ASSOC routine will associate an object with a program parameter and return a locator for it. The association can be cancelled and the locator annulled by calling DAT_CANCL.
INCLUDE 'DAT_PAR' INTEGER STATUS CHARACTER*(DAT__SZLOC) LOC CALL DAT_ASSOC( 'OBJECT', 'READ', LOC, STATUS ) ... HDS operations ... CALL DAT_CANCL( 'OBJECT', STATUS )
If DAT_ASSOC fails to associate the parameter with an object it will report the problem and prompt for a new value. It will do this up to five times before giving up and returning status PAR__NULL.
DAT_EXIST is similar to DAT_ASSOC
but it will return immediately if the association fails. It can therefore be
used to test for the existence of an object. Status PAR__ERROR
(not DAT_EXIST, for historical reasons) will be returned if the
object does not exist, but the parameter value will not be cancelled so
a subsequent HDSPAR subroutine call (such as
DAT_CREAT)
specifying the same parameter would not prompt for a new object name.
See
the example in Section for an
illustration of this.
The ACCESS Field (see SUN/115) specified in the Interface Module for the program must be compatible with the access mode specified in the DAT_ASSOC or DAT_EXIST call, otherwise status SUBPAR_ICACM will be returned.
Both routines may be called more than once for the same parameter but
DAT_CANCL must be called to cancel an existing association if a
different object is required (see
`Parameter States', Section ).
HDSPAR - HDS Parameter Routines