use Modern::Perl;
use Data::Dump qw/dump/;

my @subsections;
{
    local $/ = "\n\n";
    @subsections = <DATA>
}

say dump(@subsections);

__DATA__
subsection 1 line 1
subsection 1 line 2
subsection 1 line 3
subsection 1 line 4

subsection 2 line 1
subsection 2 line 2
subsection 2 line 3

subsection 3 line 1
subsection 3 line 2
subsection 3 line 3

subsection 4 line 1
subsection 4 line 2


##</code><code>##

open my $fh, '<', \$subsections[1];

print while <$fh>;