Some, untested, ways:

@array = $str =~ /[^][,]/g;
@array = $str =~ /[0-9]/g;
@array = split ',', substr $str, 1, -1;
@array = do {my %h = split //, $str; grep {defined} values %h};
[download]

It's hard to determine from a single, simple, example what you really want.