use strict;
use IPC::Open3;
use IO::Select;
use Symbol;

sub _run_ReadWrite {
    my ($invocant, $cmd, $input) = @_;

    # Declare needed variables
    my ($child_pid, $output, $errors, $select, $fh, @ready);
    my ($child_in, $child_out, $child_err) = (gensym, gensym, gensym);

    # Try to connect to specified process
    eval {
        $child_pid = open3($child_in, $child_out, $child_err, $cmd)
    };
    # ..... throw error if $@ .....

    # Feed input to process, then close input
    print $child_in $input; close ($child_in);

    # Create a select object and add fhs
    $select = IO::Select->new();
    $select->add($child_out, $child_err);

    # This loop will block until data is available
    while ( @ready = $select->can_read ) {
        # We now have a list of readable fhs
        foreach $fh ( @ready ) {
            # Read 4096 bytes of data
            my $data; my $len = sysread $fh, $data, 4096;
            # There was a read error
            if ( !defined $len ) {
                # ..... throw error .....
            }
            # Current filehandle is empty, remove from select object
            elsif ( $len == 0 ) { $select->remove($fh) and next } 
            # Data was read from a proper fh, add it to proper var
            elsif ( $fh == $child_out ) { $output .= $data and next }
            elsif ( $fh == $child_err ) { $errors .= $data and next }
            # There was an unexpected error
            else {
                # ..... throw error .....
            }
        }
    }

    # Process can be reaped
    waitpid($child_pid, 0);

    # Return collected results
    return { OUTPUT => $output , ERRORS => $errors };
}