Overriding CORE::GLOBAL::open

gistfile1.txt

#!/usr/bin/perl

use strict;
use warnings;
use 5.010;

BEGIN {
    no strict 'refs';
    use Symbol ();
    use Devel::Peek;

    # See https://gist.github.com/ernix/a613c09d7e5fee7f91f9
    *CORE::GLOBAL::open = sub (*;$@) {
        warn "We're opening\n";
        Dump($_[0]);
        if (defined $_[0]) {
            my $x = shift;
            unshift @_,Symbol::qualify($x, scalar caller);
        }
        Dump($_[0]);

        return CORE::open($_[0]) if @_ == 1;
        return CORE::open($_[0], $_[1]) if @_ == 2;
        return CORE::open($_[0], $_[1], $_[2]) if @_ == 3 && defined $_[2];
        return CORE::open($_[0], $_[1], undef) if @_ == 3;
        return CORE::open($_[0], $_[1], @_[2..$#_]);
    };
}

package Foo::Bar;

sub opening {
    open my $fh, '<', '/etc/passwd' or die $!;
    say scalar <$fh>;
    open FILEH, '</etc/passwd' or die $!;
    say scalar <FILEH>;
}

package main;

Foo::Bar::opening();