Yes. It is an option. It may not be the best option for your uses.

I use iterators when schlepping event logs through my monitoring system, whether they come from a real-time event queue, stored log files, or current state of a system. To my consumer software, all of the data looks the same.

The reason I suggested this technique is that it does not significantly increase the memory or filesystem requirements (as reading files fully into memory or storing in a temp file and processing would^Wcould do). It also allows the consumer (your XML processing in this case) to treat it as just a file handle. 

# UNTESTED
#
# This is for line-by-line reading, not block-by-block reading.
# Adjust as necessary.
sub create_iterator {
    my $original_fh  = \*STDIN;
    my @cached_data  = $original_fh->getline;                # enough 
+to id the file
    my $data_type_id = identify_data_type( \@cached_data );  # Remove 
+from @cached if provided

    my $iterator = iter( sub {
        my $retval;
        if ( $data_type_id ) {
            $retval = $data_type_id;
            $data_type_id = undef;
        }
        elsif ( @cached_data ) {
            $retval = shift( @cached_data );
        }
        else {
            $retval = $original_fh->getline;
        }
        return $retval;
    } );

    return $iterator;
}

[download]

--MidLifeXis

In reply to Re^3: peek at STDIN, to determine data type and then pass STDIN to a parser by MidLifeXis
in thread peek at STDIN, to determine data type and then pass STDIN to a parser by aral

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