use warnings;
use strict;


my $foo = 'there';
my $bar = 'now';

my $lines = <<'LINES';  # no interpolation here
hello $foo
goodbye $bar
LINES

open my $fh, '<', \$lines or die "opening ref: $!";

local $/ = undef;  # file slurp mode

my $file_interpolation = <<"FILE_INTERPOLATION";
pre-slurp
@{[ <$fh> ]}
post-slurp
FILE_INTERPOLATION

# can eval() step be eliminated?
my $eval_interpolation = eval "qq{$file_interpolation}";

print "$file_interpolation \n";
print "$eval_interpolation \n";

##</code><code>##

pre-slurp
hello $foo
goodbye $bar

post-slurp

pre-slurp
hello there
goodbye now

post-slurp