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tt_otype_opnum_callback_add(3)
CDE


NAME
  tt_otype_opnum_callback_add - return a callback if two opnums are equal

SYNOPSIS
  #include <Tt/tt_c.h>
  Tt_status tt_otype_opnum_callback_add(const char *otid,
					int opnum,
					Tt_message_callback f);

DESCRIPTION
  The tt_otype_opnum_callback_add function adds a callback that is
  automatically invoked when a message is delivered because it matched a
  pattern derived from a signature in the named otype with an opnum equal to
  the specified one.  The callback is defined in Tt/tt_c.h5.

  The otid argument is the identifier of the object type involved in this
  operation.  The opnum argument is the opnum of the specified otype.  The f
  argument is the message callback to be run.

RETURN VALUE
  Upon successful completion, the tt_otype_opnum_callback_add function
  returns the status of the operation as one of the following Tt_status
  values: The operation completed successfully.
  The specified object type is not the name of an installed object type.
  The pointer passed does not point to an object of the correct type for this
  operation.
  The ttsession1 process is not running and the ToolTalk service cannot
  restart it.

APPLICATION USAGE
  The tt_otype_opnum_callback_add function will only be called for messages
  delivered by virtue of matching handler signatures.  The callback cannot be
  called for observer signatures because the observer ptype is not recorded
  in the incoming message.

SEE ALSO
  Tt/tt_c.h5, tt_message_callback_add3.