Now if only you could localize a variable that represents the file position, you wouldn't have to manually save/restore its value. Hmmm....

    package Tie::Scalar::FHPos;
    use FileHandle;
    sub TIESCALAR
    {
        my( $pkg, $fh ) = @_;
        bless [$fh], $pkg;
    }
    sub FETCH
    {
        my( $self ) = @_;
        $self->[0]->tell
    }
    sub STORE
    {
        my( $self, $pos ) = @_;
        $self->[0]->seek($pos,0);
    }
[download]

Test:

open F, "< foo.dat";
our $pos;
tie $pos, 'Tie::Scalar::FHPos', \*F;

{
 local $pos = 20;
 print "$pos: ", scalar(<F>);
}
print "$pos: ", scalar(<F>);
[download]

Cool!