>perl -wMstrict -le
"package base;
   sub func {
     print q{in }, __PACKAGE__, qq{ via $_[0] got $_[1]};
     }
 package derived;
   our @ISA = qw(base);
 package main;
   my $pack = 'derived';
   $pack    ->func(42);
   'derived'->func(42);
   my $foo = 'fu';
   $pack->can(qq{${foo}nc})->(42);
   no strict 'refs';
   &{ $pack->${\qq{${foo}nc}} }(42);
   $pack->${\qq{${foo}nc}}->(42);
"
in base via derived got 42
in base via derived got 42
Use of uninitialized value in concatenation (.) or string at ...
in base via 42 got
Use of uninitialized value in concatenation (.) or string at ...
in base via derived got
Undefined subroutine &main::1 called at -e line 1.