Am Freitag, 13. Februar 2004 01:40 schrieb Larry Wall:
> On Thu, Feb 12, 2004 at 04:29:58PM -0500, Uri Guttman wrote:
> : again, confusing. why should the order of a binary operator mean so
> : much? the order of a sort key is either ascending or descending. that is
> : what coders want to specify. translating that to the correct operator
> : (cmp or <=>) and the correct binary order is not the same as specifying
> : the key sort order and key type (int, string, float).
>
> Uri is dead on with this one, guys.
As I listen to this mails, I get the feeling that something like this is
wanted:
Key generation:
@unsorted_temp = map {
$k1=$_.func1('a'); # ASC
$k2=$_.func2('we'); # DESC
[ $_, $k1, $k2 ];
} @unsorted;
Now we've got an array with keys and the objects.
Sorting:
@sorted = sort {
$a->[1] cmp $b->[1] ||
$b->[2] <=> $a->[2] ||
} @unsorted_temp;
These things would have to be said in P6.
So approx.:
@sorted = @unsorted.sort(
keys => [ { $_.func1('a'); },
{ $_.func2('we'); } ],
cmp => [ cmp, <=> ],
order => [ "asc", "desc"],
key_generation => "lazy",
);
That would explain what I want.
Maybe we could turn the parts around:
@sorted = @unsorted.sort(
1 => [ { $_.func1('a'); }, cmp, "asc"],
2 => [ { $_.func2('we'); }, <=>, "desc"],
);
or maybe use a hash instead of an array:
@sorted = @unsorted.sort(
1 => [ key => { $_.func1('a'); }, op => cmp, order => "asc"],
2 => [ key => { $_.func2('we'); }, op => <=>, order => "desc"],
);
If that's too verbose? I don't think so; I've stumbled often enough on $a <=>
$b vs. $b <=> $a and similar, and the above just tells what should be done.
Regards,
Phil
