Rhandom has asked for the wisdom of the Perl Monks concerning the following question:

Without going into details, I would like to munge reading from STDIN and writing to STDOUT into one handle. I have tried writing my own IO::Handle sub class but haven't been able to get it to deal with <$handle> and print $handle "blah\n" simultaneously. Preferably I would like to avoid forking (I know that I can fork and get it to work with some effort). I would essentially like to do something like the following: 
use MyIO::Handle ();
my $io = MyIO::Handle->new(); # ISA IO::Handle
$io->fdopen(fileno(STDIN), 'r');
$io->fdopen(fileno(STDOUT),'w'); # don't block over STDIN

my $line = <$io>;
print $io "You said $line";

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Any ideas, or is it really even feasible?

Replies are listed 'Best First'.
Re: Munging STDIN and STDOUT into one handle
by japhy (Canon) on Feb 13, 2001 at 22:51 UTC
    You can do things like: 
    package TwoWayHandle;

sub TIEHANDLE {
  my ($class, $in, $out) = @_;
  bless [ \$in, \$out ], $class;
}

sub PRINT {
  my $self = shift;
  local *FH = ${ $self->[1] };
  print FH @_;
}

sub READLINE {
  my $self = shift;
  local *FH = ${ $self->[0] };
  <FH>;
}

1;

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    And then use it as: 
    use TwoWayHandle;
tie *ACDC, TwoWayHandle => (
  *STDIN,
  *STDOUT,
) or die "can't tie *ACDC: $!";

print ACDC "What's your name? ";
$name = <ACDC>;
chomp $name;
print ACDC "Hello, $name.\n";

    [download]
    Not sure why, but I can't call chomp() at the same time I read from the filehandle.

    japhy -- Perl and Regex Hacker
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Re: Munging STDIN and STDOUT into one handle
by chromatic (Archbishop) on Feb 13, 2001 at 22:53 UTC
    You could tie a handle, providing a READ method that reads from STDIN and a PRINT method that writes to STDOUT.

    That's about the simplest approach I can think of, especially if you subclass Tie::Handle.

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