It is OK because:

for (@items) {
      return 0 unless $self->($_);
}
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'for' localizes $_ correctly and therefor $_ is what you expect it to be. This is perfectly OK.

How about this btw.:

sub filter (&@){
    my $sub = shift;
    for(@_){ return unless $sub->() }
    1
}
print +( filter {/foo/} qw/foobar foobar bazfoo/ )
    ? 'y' : 'n' , "\n";
[download]

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