DB<1> use constant foo => 1 DB<2> print 1-foo Ambiguous use of -foo resolved as -&foo() at (eval 15)[/usr/lib/perl5/5.8.0/perl5db.pl:17] line 2. eval '($@, $!, $^E, $,, $/, $\\, $^W) = @saved;package main; $^D = $^D | $DB::db_stop; print 1-foo; ;' called at /usr/lib/perl5/5.8.0/perl5db.pl line 17 DB::eval called at /usr/lib/perl5/5.8.0/perl5db.pl line 1323 DB::DB called at -e line 1 0