hasenbraten has asked for the wisdom of the Perl Monks concerning the following question:

Hi,

I need to sort a list with a customized sort order, e.g. (a,c,d,e,b). This works fine as long I give the sortorder in the sort_sub like this: 

@tobesorted=(b,a,d);
@sorted=sort by_list @tobesorted;

sub by_list{
@sortorder=(a,c,d,e,b);
map { if ($a eq $sortorder[$_]){$ai=$_} } 0..$#sortorder;
map { if ($b eq $sortorder[$_]){$bi=$_} } 0..$#sortorder;
$ai <=> $bi;
}

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Nevertheless is there a possibility to hand over the list to the sub like: 

@sorted=sort by_list(\@sortorder) @tobesorted;
....
sub by_list{
@sortorder=@{$_[0]};
.....

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I cant get the argument handed over to the sort_sub. Has that to do with the "local ($a,$b)" used for sort ? Any hints to write the code more elegant are appreciated.

Thanks, Hasenbraten

Replies are listed 'Best First'.
Re: give arguments to sort_sub
by Fletch (Bishop) on Apr 12, 2004 at 00:26 UTC 
    @sorted = sort { by_list( \@sortorder ) } @tobesorted;

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    Update: Or if you do it more than once with a few common orders: 

    sub make_sorter {
  my $order = shift;
  return sub { by_list( $order ) };
}
my $order1 = make_sorter( [ qw( a c d e b f ) ] );
my $order2 = make_sorter( [ qw( f b a d c e ) ] );
my @order1 = sort $order1, @tobesorted;
my @order2 = sort $order2, @tobesorted;
my @other2 = sort $order2, @othertobesorted;

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•Re: give arguments to sort_sub
by merlyn (Sage) on Apr 12, 2004 at 00:31 UTC
[reply]

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