package base;

sub function { }

package derived;

our @ISA = qw|base|;

package main;

derived->function(); # <-- works, not what I want

my $pack = "base";
&{"${pack}::functon"}(); # <-- works, not what I want

$pack = "derived";
&{"${pack}::function"}(); # <-- doesn't work, this is what I want

$pack = "derived";
eval "${pack}->function()"; # <-- works, not what I want