if ($category_id eq "all") {
        push @all_matches, SomethingAll(...);
    }
    elsif ($category_id eq "subj") {
        push @all_matches, SomethingSubj(...);
    }

##</code><code>##

my %dispatch_table = (
   all => \&SomethingAll
   subj => \&SomethingSubj
   _default => \&SomethingDefault
);
...
my $callback = $dispatch_table{$category_id} || $dispatch_table{_default};
push @all_matches, $callback->(...);