use XML::Checker::Parser;

my %expat_options = (KeepCDATA => 1,
                      Handlers => [ Unparsed => \&my_Unparsed_handler ]);

my $parser = new XML::Checker::Parser (%expat_options);

eval {
    local $XML::Checker::FAIL = \&my_fail;
    $parser->parsefile ("valid.xml");
};

if ($@) {
    print "Either XML::Parser (expat) threw an exception or my_fail() died.";
}

 # Throws an exception (with die) when an error is encountered, this
 # will stop the parsing process.
 # Don't die if a warning or info message is encountered, just print a message.
 sub my_fail {
     my $code = shift;
     die XML::Checker::error_string ($code, @_) if $code < 200;
     XML::Checker::print_error ($code, @_);
 }

sub my_Unparsed_handler {
    print "!";
}