2467c2467
<       $param_map->{$param}[HTML::Template::LOOP::PARAM_SET] = [@{$value}];
---
>       $param_map->{$param}[HTML::Template::LOOP::PARAM_SET] = $value;
2612c2612
<         eval { $result .= $line->output($x, $options->{loop_context_vars}); };
---
>         eval { $line->output($x, $options->{loop_context_vars},\$result); };
2885a2886,2888
>   my $result;
>   my $blank = "";
>   $result = shift or $result = \$blank;
2906c2908
<     $result .= $template->output;
---
>     ${$result} .= $template->output;
2914c2916
<   return $result;
---
>   return ${$result};

##</code><code>##

package Tie::Array::SubIterator;

use base Tie::Array;

sub TIEARRAY {
  my $class = shift;
  my %in = @_;
  $in{'length'} = -1 unless $in{'length'} && $in{'length'} =~ /^\d$/;
  die "Expected coderef for next option" unless ref($in{'next'}) eq "CODE";
  die "Expected coderef for determine_end option" unless !defined($in{'determine_end'}) or $in{'length'} < 0 or ref($in{'determine_end'}) eq "CODE";
  $in{'determine_end'} = sub { return defined(+shift->{'last_result'}) ? 0:1; } if (!$in{'determine_end'} && $in{'length'} < 0);
  $in{'last_counted'} = 0;
  $in{'ended'} = 0;
  my $self = bless \%in, $class; 
  eval { $self->{'last_result'} = $self->{'next'}->($self,0) if $self->{'length'} < 0; };
  $self->{'ended'} = 1 if $@;
  return $self;
}

sub FETCH {
  my $self = shift;
  return $self->{'next'}->($shift,@_) if ($self->{length} > -1); 
  my $last = $self->{'last_result'};
  eval { $self->{'last_result'} = $self->{'next'}->($self,++$_[0]) unless $self->{'ended'}; };
  $self->{'ended'} = 1 if $@;
  return $last;
}

sub FETCHSIZE { 
  $self = shift;
  return $self->{'length'} if $self->{'length'} > -1;
  ++$self->{'last_counted'} unless ($self->{'ended'}) || ($self->{'ended'} = $self->{determine_end}->($self));
  $self->{'last_counted'};
}

sub DESTROY {
  my $self = $_[0];
  $self->{destroy}->(@_) if ref($self->{destroy}) eq "CODE";
}

1;

##</code><code>##

#!/usr/bin/perl -w

use strict;
use Tie::Array::SubIterator;
use HTML::Template;
use Devel::Size qw(total_size);

my @array= (1..10_000);

sub next {
  my $self = shift;
  return undef if $_[0] > $#array;
  return { num => $array[$_[0]], added => $array[$_[0]]+10, subtracted => $array[$_[0]]-10 };
}

my @old_method;
push @old_method, { "num" => $_, "added" => ($_ + 10), subtracted => $_-10 } for (@array);

print "old: ", total_size(\@old_method),$/;
print "new: ", total_size(\@array),$/;

tie my @data, "DMN::TieArrayForeach", next=>\&next;

my $tmpl = q|<tmpl_var bob>
<tmpl_loop data>
<br><tmpl_var num> <tmpl_var added> <tmpl_var subtracted><br>
</tmpl_loop>
<tmpl_var bob>|;

my $template = HTML::Template->new(scalarref => \$tmpl);
$template->param(data => \@old_method,bob=>"outer area");
my $one = $template->output();
$template->param(data => \@data,bob=>"outer area");
my $two = $template->output();

print "identical$/" if $one eq $two;

##</code><code>##

old: 2145624
new: 240056
identical