Re^2: Help with Hash of hashes, is there a better way?

[TeraMarv]

in reply to Re: Help with Hash of hashes, is there a better way?
in thread Help with Hash of hashes, is there a better way?

wfsp,

I suppose i'm not happy with the nested loops as i have to traverse the structure several times in the code and that requires using the same bit of code again and again. Any bit of code that gets used more than once is crying out for a function to be written. Unfortunately either my skills,imagination or experience isn't quite up to it.

Any ideas?

[wfsp]

Some thoughts.
• I could live with 'several' and not worry too much. :-)
• You could do everything in one pass.
• You could consider putting your traversing loops into a sub and pass a sub ref for the particular work that needs to be done.

HTH

[friedo]

that requires using the same bit of code again and again.

Whenever I see this phrase, deafening alarm bells and sirens go off in my head. In the vast majority of cases, any time you're using the same (or similar) chunk of code over and over again, you can probably do better with a subroutine. In the case of a sub for traversing a complex data structure, you may want to use a callback hook to provide the specific functionality.

[bart]

There are modules available on CPAN to traverse complex data structures. One that I'm aware of is nothingmuch's Data::Visitor::Callback, but I'm sure there are more...

Data::Traverse looks like it fits the bill, too.

[ikegami]

Option 1)

You could build an iterator, seperating the traversal from the client as demonstrated by the following:

{
   my $iter = get_target_iter($stuff);

   while (my (
      $env_name,
      $platform_name,
      $host_name,
      $target_name,
      $total_capacity,
      $free_capacity,
   ) = $iter->()) {
      local $, = "\t";
      local $\ = "\n";

      print $env_name,
            $platform_name,
            $host_name,
            $target_name,
            $total_capacity,
            $free_capacity;
   }
}

Read more... sub get_target_iter (2 kB)

Tested.

Update: Below is an alternative iterator. It's a drop-in replacement for the above function. This version is much smaller thanks to Algorithm::Loops's NestedLoops.

Read more... Alternative sub get_target_iter (1393 Bytes)

Tested.

[ikegami]

Option 2)

A callback would be simpler:

{
   iterate {
      my (
         $env_name,
         $platform_name,
         $host_name,
         $target_name,
         $total_capacity,
         $free_capacity,
      ) = @_;
   
      local $, = "\t";
      local $\ = "\n";

      print $env_name,
            $platform_name,
            $host_name,
            $target_name,
            $total_capacity,
            $free_capacity;
   } $stuff;
}

Read more... sub iterate (906 Bytes)

Tested.

[TeraMarv]

Thanks ikegami,

I like it, very cool. Something I would never have come up with myself....well at least not this year ;-)

That's what I love about perlmonks, you always learn something useful.

Thanks again....to all Monks