I'm assuming you have a block somewhat like the following?

# ouch
open(my $fh, '>', 'data.tmp') or die("open failed: $!");
$template->output(print_to => $fh);
close($fh);

open(my $fh, '<', 'data.tmp') or die("open failed: $!");
chomp( my @template_txt = <$fh> );
close($fh);
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Or maybe you're doing more harm than that even?

# major ouch
open(my $fh, '>', 'data.tmp') or die("open failed: $!");
print $fh $template->output();
close($fh);

open(my $fh, '<', 'data.tmp') or die("open failed: $!");
chomp( my @template_txt = <$fh> );
close($fh);
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Either way, the output() method without the 'print_to' parameter will return the template text as a scalar. If you want each line of the template text to be its own array entry (or all in one scalar), you'd want this:

# one line per array entry, no ouch
my @template_txt = split( /\n/, $template->output() );

# all in one scalar, no ouch
my $template_txt = $template->output();
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update: minor updates to the original 'ouch' possibilities, in order to include the reading of file to array.