Fully qualified name of currently executing subroutine.

=item  $DB::lineno

Line number that will be executed next.

=back

=head2 API Methods

The following are methods in the DB base class.  A client must
access these methods by inheritance (*not* by calling them directly),
since the API keeps track of clients through the inheritance
mechanism.

=over 8

=item CLIENT->register()

register a client object/package

=item CLIENT->evalcode(STRING)

eval STRING in executing code context

=item CLIENT->skippkg('D::hide')

ask DB not to stop in these packages

=item CLIENT->run()

run some more (until a breakpt is reached)

=item CLIENT->step()

single step

=item CLIENT->next()

step over

=item CLIENT->done()

de-register from the debugging API

=back

=head2 Client Callback Methods

The following "virtual" methods can be defined by the client.  They will
be called by the API at appropriate points.  Note that unless specified
otherwise, the debug API only defines empty, non-functional default versions
of these methods.

=over 8

=item CLIENT->init()

Called after debug API inits itself.

=item CLIENT->prestop([STRING])

Usually inherited from DB package.  If no arguments are passed,
returns the prestop action string.

=item CLIENT->stop()

Called when execution stops (w/ args file, line).

=item CLIENT->idle()

Called while stopped (can be a client event loop).

=item CLIENT->poststop([STRING])

Usually inherited from DB package.  If no arguments are passed,
returns the poststop action string.

=item CLIENT->evalcode(STRING)

Usually inherited from DB package.  Ask for a STRING to be C<eval>-ed
in executing code context.

=item CLIENT->cleanup()

Called just before exit.

=item CLIENT->output(LIST)

Called when API must show a message (warnings, errors etc.).


=back


=head1 BUGS

The interface defined by this module is missing some of the later additions
to perl's debugging functionality.  As such, this interface should be considered