Unless you have some expectaton of subclassing this, the object orientation seems like overkill.

Also, for general purpose use, UNIVERSAL is probably better than the stringification/regex approach, as it plays better with string overloading.

A further speed improvement can be gained by using list processing to avoid recursive calling: 

use strict;
use UNIVERSAL 'isa';

sub deep_grep (&@) {
  my $test = shift;
  
  my ( @results, %seen );
  
  while ( scalar @_ ) {
    my $target = shift @_;
    
    push @results, grep $test->( $_ ), $target; 
    
    unshift @_, $seen{$target} ++        ? ()              : 
                  isa($target, 'HASH')   ? values %$target :
                  isa($target, 'ARRAY')  ? @$target        :
                  isa($target, 'REF')    ? $$target        :
                  isa($target, 'SCALAR') ? $$target        : ();
  }
  return @results;
}

[download]

The prototype allows you to call it blockwise, like the builtin grep, but isn't needed: 

my @loggers = deep_grep( sub { isa( $_, 'Log' ) }, $target );

my @loggers = deep_grep { isa( $_, 'Log' ) } $target;

[download]

In reply to Re^3: searching for an object reference by simonm
in thread searching for an object reference by Anonymous Monk

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