Accoring to the documentation for sort, it expects a function that returns -1, 0, or 1 for (a<b),(a==b),(a>b), respectively. So, that's all your sub needs to do. 

# note passing your sub $a and $b
foreach my $id (sort { mysort($direction,$a,$b) } keys %hash) {
  print "$id - $hash{$id}{$orderby}\n";
} # end-foreach

sub mysort {
    my ($direction, $_a, $_b) = @_;
    my $result =  
        $hash{$_a}{$orderby} <=> $hash{$_b}{$orderby}
        || $hash{$_a}{$orderby} cmp $hash{$_b}{$orderby};
    
    # default to ascending, but if the dir is 'DESC', we
    # return the *opposite* answer
    return ($direction eq 'DESC') ? -($result) : $result;
}

[download]

Untested, of course, but the idea should be basically sound. If I understand what you're trying to accomplish, though, you might take a different approach. 

# we pass the sub the actual values to compare
foreach my $id (
  sort { mysort($direction,$hash{$a}{$orderby},$hash{$b}{$orderby}) } 
+keys %hash
) {
    print "$id - $hash{$id}{$orderby}\n";
} # end-foreach

sub mysort {
    my ($direction, $_a, $_b) = @_;
    # generalized, simplified comparison
    my $result = $_a <=> $_b || $_a cmp $_b;
    
    # default to ascending, but if the dir is 'DESC', we
    # return the *opposite* answer
    return ($direction eq 'DESC') ? -($result) : $result;
}

[download]
<-radiant.matrix->
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In reply to Re: sort direction by radiantmatrix
in thread sort direction by rsiedl

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