How can get a filehandle for a Perl program's output?

Question

I have an encrypted file X1, I have a Perl program P1 that decrypts the X1. I am parsing the decrypted file using a Perl program p2.

X1--P1(decrypter) --> X2(plain text file) --p2(parser) --> parse output

My parser is based on XML::Parser. It can work with a filehandle to the decrypted file. Now I am getting the X2 and storing it in the file system and reading it in the P2 and parsing it. Is there way I can directly get the filehandle over the P1's output and use that filehandle in the P2 to parse it directly with out requiring a temporary file?

Answer 1

Say you're using very weak encryption:

#! /usr/bin/perl

print <<EOXML;
<doc>
  <elem attr="Hello, world!" />
</doc>
EOXML

Using open $fh, "-|", ... will create a pipe connected to the standard output of a child process:

#! /usr/bin/perl

use warnings;
use strict;

open my $decrypted, "-|", "./decrypt"
  or die "$0: open: $!";

while (<$decrypted>) {
  print "got: $_";
}

Output:

got: <doc>
got:   <elem attr="Hello, world!" />
got: </doc>