$op_map{$op_choice}->(@args);

##</code><code>##

&{$op_map{$op_choice}}(@args);

##</code><code>##

die "Unknown choice: $op_choice\n"
  unless my $cmd = $op_map{$op_choice};

##</code><code>##

my $default = 'OP1';
my $cmd = $op_map{$op_choice} || $op_map{$default};

##</code><code>##

$cmd->();

##</code><code>##

&$cmd; # see WARNING below