use IO::Handle;
my $captured = IO::Handle->new;
tie *$captured, 'Capture::Handle',
    handle => $captured
    or die "Couldn't tie *CAPTURED: $!";
select CAPTURED;

print ....

my $captured = tied(*CAPTURED)->get_captured;

package Capture::STDOUT;
sub TIEHANDLE {
    my $class = shift;
    bless { @_ }, $class
}
sub set_handle { shift()->{'handle'} = shift }
sub get_handle { shift()->{'handle'} }
sub PRINT {
    my $self = shift;
    print $self->{'handle'} @_;
    push @{$self->{'captured'}}, @_;
}
sub get_captured { @{shift()->{'captured'}} }