Set an action to be done before the line is executed.
The sequence of steps taken by the debugger is
-=over 3
-
-=item 1
-
-check for a breakpoint at this line
-
-=item 2
-
-print the line if necessary (tracing)
-
-=item 3
-
-do any actions associated with that line
-
-=item 4
-
-prompt user if at a breakpoint or in single-step
-
-=item 5
-
-evaluate line
-
-=back
+ 1. check for a breakpoint at this line
+ 2. print the line if necessary (tracing)
+ 3. do any actions associated with that line
+ 4. prompt user if at a breakpoint or in single-step
+ 5. evaluate line
For example, this will print out C<$foo> every time line
53 is passed:
See L<"Debugger Internals"> below for more details.
+=over 12
+
=item E<lt> [ command ]
Set an action (Perl command) to happen before every debugger prompt.