Dear ikegami,
To confirm my understanding on the use of "local our".
You mean in this context right?

foreach my $ss (@str_set) {
    local our @matches;
    $ss =~ m/
          (XXX.*YYY)                 # Search and capture
          (?{ push @matches, $1 })   # Save result
          (?!)                       # Try again
         /x;
    print Dumper \@matches ;
}
[download]

Namely if I use "my" instead it will return:

$VAR = [ # with something ]

# and then empty....

$VAR = [];
$VAR = []; 

etc...
[download]