general mechanisms is enabled by calling Perl with the B<-d> switch, the
following additional features are enabled (cf. L<perlvar/$^P>):
-=over
+=over 4
=item *
=item *
-The array C<@{"_<$filename"}> holds the lines of $filename for all
-files compiled by Perl. The same for C<eval>ed strings that contain
+Each array C<@{"_<$filename"}> holds the lines of $filename for a
+file compiled by Perl. The same for C<eval>ed strings that contain
subroutines, or which are currently being executed. The $filename
for C<eval>ed strings looks like C<(eval 34)>. Code assertions
-in regexes look like C<(re_eval 19)>.
+in regexes look like C<(re_eval 19)>.
+
+Values in this array are magical in numeric context: they compare
+equal to zero only if the line is not breakable.
=item *
-The hash C<%{"_<$filename"}> contains breakpoints and actions keyed
+Each hash C<%{"_<$filename"}> contains breakpoints and actions keyed
by line number. Individual entries (as opposed to the whole hash)
are settable. Perl only cares about Boolean true here, although
the values used by F<perl5db.pl> have the form
-C<"$break_condition\0$action">. Values in this hash are magical
-in numeric context: they are zeros if the line is not breakable.
+C<"$break_condition\0$action">.
The same holds for evaluated strings that contain subroutines, or
which are currently being executed. The $filename for C<eval>ed strings
=item *
-The scalar C<${"_<$filename"}> contains C<"_<$filename">. This is
+Each scalar C<${"_<$filename"}> contains C<"_<$filename">. This is
also the case for evaluated strings that contain subroutines, or
which are currently being executed. The $filename for C<eval>ed
strings looks like C<(eval 34)> or C<(re_eval 19)>.
The fields of interest which may appear in the last line are
-=over
+=over 4
=item C<anchored> I<STRING> C<at> I<POS>
Here is some explanation of that format:
-=over
+=over 4
=item C<buckets SMALLEST(APPROX)..GREATEST(APPROX)>
Here are explanations for other I<Id>s above:
-=over
+=over 4
=item C<717>
If warn() string starts with
-=over
+=over 4
=item C<!!!>