This doesn't work for IO::Scalar filehandles however:

    #!/usr/bin/perl -w

    use strict;
    use IO::Scalar;

    my $str;
    tie *TMP, 'IO::Scalar', \$str;

    print TMP "Hello, World!\n";

    print "Not a FH\n" unless defined eval {fileno \*TMP};
[download]

I also tested it with IO::Socket::INET filehandles and it works for those.

--
John.