http://qs321.pair.com?node_id=1114788


in reply to How can I access object data in a user defined sort cmp function?

why do you need a custom function byvalue() ?

Even sorting the keys of a normal hash by value¹ can only be done by somehow tunneling the reference into byvalue() by closure/currying (like choroba showed) or by doing a (schwarzian?) transform of the hash into an array of key/value-tupels.

Both approaches look like overkill if you can do this straightforwardly:

my %h = %{$self->{hash_ref}}; my @keys = sort { $h{$a} <=> $h{$b} } keys %h;

Easy to read, easy to understand.

So why ?

DB<100> $self={ hash_ref=>{item1=>'value1',item2=>'value2'} } => { hash_ref => { item1 => "value1", item2 => "value2" } } DB<101> %h=%{$self->{hash_ref}} => ("item1", "value1", "item2", "value2") DB<103> @keys=sort {$h{$a}<=>$h{$b}} keys %h; => ("item1", "item2")

Cheers Rolf

PS: Je suis Charlie!

PS: downvoted for lack of indentation, I agree with the Guido comment.

¹) hint "Reduction to a simpler problem"!

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Re^2: How can I access object data in a user defined sort cmp function?
by tkguifan (Scribe) on Jan 28, 2015 at 17:48 UTC
    Of course I have tried to use identation, but whenever I type TAB, it takes me off the edit box, so I gave up.
      Don't type code into the text area, copy&paste it from your favourite editor where you can also check its syntax with syntax highlighting and test it by running it.
      لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ
      > but whenever I type TAB, it takes me off the edit box

      SPACE! Man! ;-)

      Cheers Rolf

      PS: Je suis Charlie!

      PS: Choroba is right it's not feasible to hack several lines without typo, and you can't expect others to fiddle with them.

      But since these are your first posts I should have gone easier on you. Sorry!