Hi monks!

I want to see if I can make the following more efficient, or if it's worth the bother..

I'm parsing through some listing results from the EC2 api commands, getting lists of snapshots/volumes; I have an array  @snapshot_listing, it's a bunch of lines and looks like this.. 

TAG     snapshot  snap-162c4c78   Name    rotation-snap-msgin-msginvol
+-vol-28fb2141-1306254741
TAG     snapshot  snap-182ce47a   Name    rotation-snap-msgin-msginvol
+-vol-22fb2a40-1306253728
TAG     snapshot  snap-3e02ee50   Name    rotation-snap-util-backupvol
+-vol-11cb3d7a-1307246947
TAG     snapshot  snap-133c4c7e   Name    rotation-snap-msgin-msginvol
+-vol-28fb2140-1306254729
TAG     snapshot  snap-112ae52a   Name    rotation-snap-msgin-msginvol
+-vol-28fb2140-1307254721
TAG     snapshot  snap-2e0a6e5f   Name    rotation-snap-util-backupvol
+-vol-14ca3d7a-1308456945

[download]

My little name tags have a timestamp on the end, so I want to extract that out when I build up the following hash, so I can decide which objects are old enough to delete.. I have an hoa where the key is my timestamp.. 

my %snapshot_roster = map {
      ($k,$v) = (split /\s+/,$_)[2,4];
      strip_stamp($v) => [ $k, $v ];          
   } @snapshot_listing;

sub strip_stamp
{
   /-([\d]+)$/ and return $1;
}

[download]

I could get rid of the subroutine, and do the string construction for the hash key on the fly 

   $v=~/-([\d]+)$/ ? $1 : undef => [ $k, $v ];

[download]
and although this works, it somehow seem dangerous and not the safest way to do it... are there cases where $v could get overwritten (it's not right now somehow), and undef seems like the wrong other choice if by chance the string comparison doesn't have my expected timestamp on the end... maybe time() instead of undef .. any suggestions on how to better think this through ?

-Harold

In reply to HoA create from array using map, more efficient? by hsinclai

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