How To Call An Anonymous Subroutine?

Plankton has asked for the wisdom of the Perl Monks concerning the following question:

Dear Wise Monks

I am having trouble getting an anonymous sub routine to execute.

#!/usr/bin/perl -w
use strict;

my %new_resolvers = (
   'dns-one'          => [
      "127.0.0.1\tdns-apple"
    , "127.0.0.2\tdns-banana"
    , "127.0.0.3\tdns-shoe"
    ]
    ,  'dns-extern'    => [ 
    sub {
       my $ip = shift or die "you need to pass in IP address";
       my @array;
       open ( PIPE, "./get_resolvers_for_client.sh|" ) 
          or die __FILE__ . " [" . __LINE__ . "] could not open get_re
+solvers_for_client.sh:$!";
       while ( <PIPE> ) {
          chomp;
          last if /not a one of our IP addresses/;
          push ( @array, $_ );
       }
       return reverse @array;
    }
    ]
);

for my $dns_server ( keys %new_resolvers )  {
   print "getting new resolvers for dns server $dns_server\n";
   my $resolvers           = join "\n", @{$new_resolvers{$dns_server}}
+;
   print "$resolvers\n\n";
}
[download]

When I run my script I get this output ...


getting new resolvers for dns server dns-extern
CODE(0x92fe808)

getting new resolvers for dns server dns-one
127.0.0.1       dns-apple
127.0.0.2       dns-banana
127.0.0.3       dns-shoe
[download]

What am I doing wrong here? How do I invoke the anonymous sub? Thank you.

Comment on How To Call An Anonymous Subroutine? Select or Download Code

Replies are listed 'Best First'.
Re: How To Call An Anonymous Subroutine? by runrig (Abbot) on Apr 25, 2012 at 18:07 UTC
You invoke an anonymous sub with `->()`. Your sub would be invoked with `$new_resolvers{"dns-extern"}[0]->($ip_address)`. The way you have your loop written, you'll have to tell the difference between a scalar and a sub though. You could rewrite the loop as: `print "getting new resolvers for dns server $dns_server\n"; for my $resolver ( @{$new_resolvers{$dns_server}} ) { if (ref $resolver) { print "$_\n" for $resolver->($ip); } else { print "$resolver\n\n"; } } print "\n";` [download] I don't know where `$ip` is supposed to come from, but that's the way you have your anonymous sub written.	[reply] [d/l] [select]
Re^2: How To Call An Anonymous Subroutine? by Plankton (Vicar) on Apr 25, 2012 at 19:31 UTC
Thank you runrig. that's what I needed!	[reply]

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