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

Hello Monks,

I'm trying to use the Seen() method of Data::Dumper to make coderefs show as something more useful than sub { "DUMMY" }, but I'm not having any luck, and I don't understand the example in the documentation - can anyone help me out? 

use Data::Dumper;
$foo = sub {return []};
$bar = {arefpromise => $foo};
$d = Data::Dumper->new([$bar]);
print "foo is a coderef $foo returning ".$foo->()."\n";
$d->Seen ({$foo => $foo->()});
print $d->Dump();

[download]

outputs:

foo is a coderef CODE(0x8154684) returning ARRAY(0x8153c28)
$VAR1 = {
          'arefpromise' => sub { "DUMMY" }
        };

[download]


Basically, in the output of Data::Dumper I'd like to get the thing a coderef would return, or maybe the string overload of the package of $foo - in fact, wouldn't 'arefpromise' => sub { "CODE(0x8154684)" } be a more useful default?

Thanks!

Replies are listed 'Best First'.
Re: using Data::Dumper->Seen() with coderefs?
by tilly (Archbishop) on Jan 11, 2009 at 00:54 UTC
    You need to set $Data::Dumper::Deparse to a true value. 
    use Data::Dumper;
$Data::Dumper::Deparse = 1;
$foo = sub {return []};
$bar = {arefpromise => $foo};
$d = Data::Dumper->new([$bar]);
print "foo is a coderef $foo returning ".$foo->()."\n";
$d->Seen ({$foo => $foo->()});
print $d->Dump();

    [download]
    will print 
    foo is a coderef CODE(0x801734) returning ARRAY(0x801944)
$VAR1 = {
          'arefpromise' => sub {
                               return [];
                           }
        };

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