my $plugin = ...;

my $pm = $plugin;
$pm =~ s{::}{/}g;
$pm .= '.pm';
eval { require $pm }
   or die("Unable to load plugin $plugin: $@\n");

# Example static method call.
$plugin->method();

# Example function call.
my $func = do { no strict 'refs'; *{"${plugin}::func"}{CODE} }
   or die("Undefined function func in plugin $plugin\n");
$func->();