...
unless( is_filehandle( $arg ) {
    open $arg, '...', $arg or die $!;
}
...

##</code><code>##

#! perl -slw
package main;
use strict;
use FileHandle;
use IO::File;
use IO::Socket::INET;

sub ok{
    my( $code, $wanted, $label, $value ) = @_;
    my $bool = $code->( $value );
    return $label . ':' . ( $bool == $wanted ? 'Ack' : 'Nak' );
}

sub isIO {
    my $arg = shift;
    my $p = eval{ fileno( $arg ) };
    return defined( $p ) && $p >=0 ? 1 : 0;
}

my @handles = (
    [0, "1",           1],
    [0, "hashref",     {}],
    [0, "arrayref",    []],
    [0, "globref",     \*INC],
    [1, "in-memory",   do {{ my $buf; open my $fh, "<", \$buf; $fh }}],
    [1, "FH1 glob",    do {{ open FH1, "<", "nul"; *FH1 }}],
    [1, "FH2 globref", do {{ open FH2, "<", "nul"; \*FH2 }}],
    [1, "FH3 string",  do {{ no strict; $FH3 = 'nul'; open FH3; FH3 }}],
    [1, "STDIN glob",  \*STDIN],
    [1, "STDOUT glob",  \*STDOUT],
    [1, "plain read",  do {{ open my $fh, "<", "nul"; $fh }}],
    [1, "plain write", do {{ open my $fh, ">", "nul"; $fh }}],
    [1, "FH read",     FileHandle->new("< nul")],
    [1, "FH write",    FileHandle->new("> nul")],
    [1, "I::F read",   IO::File->new("< nul")],
    [1, "I::F write",  IO::File->new("> nul")],
    [1, "pipe read",   do {{ open my $fh, "ver |"; $fh }}],
    [1, "pipe write",  do {{ open my $fh, "| more"; $fh }}],
    [1, "socket",      IO::Socket::INET->new(LocalAddr => sprintf('localhost:%d', 10000 + rand 20000))],
);

print ok( \&isIO, @$_ ) for @handles;


__END__
1:Ack
hashref:Ack
arrayref:Ack
globref:Ack
in-memory:Nak
FH1 glob:Ack
FH2 globref:Ack
FH3 string:Ack
STDIN glob:Ack
STDOUT glob:Ack
plain read:Ack
plain write:Ack
FH read:Ack
FH write:Ack
I::F read:Ack
I::F write:Ack
pipe read:Ack
pipe write:Ack
socket:Ack

##</code><code>##

#! perl -slw
package main;
use strict;
use FileHandle;
use IO::File;
use IO::Socket::INET;

sub ok{
    my( $code, $wanted, $label, $value ) = @_;
    my $bool = $code->( $value );
    return $label . ':' . ( $bool == $wanted ? 'Ack' : 'Nak' );
}

sub isIO{
    local $^W;
    my $arg = shift;
    my $p = eval{ tell( $arg ) };
    return defined( $p ) && $p >=0 ? 1 : 0;
}

my @handles = (
    [0, "1",           1],
    [0, "hashref",     {}],
    [0, "arrayref",    []],
    [0, "globref",     \*INC],
    [1, "in-memory",   do {{ my $buf; open my $fh, "<", \$buf; $fh }}],
    [1, "FH1 glob",    do {{ open FH1, "<", "nul"; *FH1 }}],
    [1, "FH2 globref", do {{ open FH2, "<", "nul"; \*FH2 }}],
    [1, "FH3 string",  do {{ no strict; $FH3 = 'nul'; open FH3; FH3 }}],
    [1, "STDIN glob",  \*STDIN],
    [1, "STDOUT glob",  \*STDOUT],
    [1, "plain read",  do {{ open my $fh, "<", "nul"; $fh }}],
    [1, "plain write", do {{ open my $fh, ">", "nul"; $fh }}],
    [1, "FH read",     FileHandle->new("< nul")],
    [1, "FH write",    FileHandle->new("> nul")],
    [1, "I::F read",   IO::File->new("< nul")],
    [1, "I::F write",  IO::File->new("> nul")],
    [1, "pipe read",   do {{ open my $fh, "ver |"; $fh }}],
    [1, "pipe write",  do {{ open my $fh, "| more"; $fh }}],
    [1, "socket",      IO::Socket::INET->new(LocalAddr => sprintf('localhost:%d', 10000 + rand 20000))],
);

print ok( \&isIO, @$_ ) for @handles;

__END__
[ 6:39:21.75] C:\test>junk6
1:Ack
hashref:Ack
arrayref:Ack
globref:Ack
in-memory:Ack
FH1 glob:Ack
FH2 globref:Ack
FH3 string:Ack
STDIN glob:Ack
STDOUT glob:Ack
plain read:Ack
plain write:Ack
FH read:Ack
FH write:Ack
I::F read:Ack
I::F write:Ack
pipe read:Ack
pipe write:Ack
socket:Ack