tt_otype_opnum_callback_add(3)

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.h>.

     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:

        TT_OK   The operation completed successfully.

        TT_ERR_OTYPE
                The specified object type is not the name of an installed
                object type.

        TT_ERR_POINTER
                The pointer passed does not point to an object of the correct
                type for this operation.

        TT_ERR_NOMP
                The ttsession(1) 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
     Tttt_c(5), tt_message_callback_add(3).