Re^2: Emptying (and refilling) an array.

Thanks for the critique: I've updated my benchmarks with something hopefully a little better.

Yes, I was thinking of undef @working. Fixed.

I kept meaning to get those off-by-one errors matched up, but I knew it didn't actually make a difference... My bad.

$#working = 100; actually isn't part of what I was looking at: I was specifically looking at an array that (usually) already has a length.

my @working; is the same as my @working = (); when @working doesn't exist. Once it does, the latter does seem to actually clear the array. (As far as I can tell: My code that should throw errors if it didn't.)

Comment on Re^2: Emptying (and refilling) an array. Select or Download Code

Replies are listed 'Best First'.
Re^3: Emptying (and refilling) an array. by ikegami (Patriarch) on Jan 12, 2009 at 16:38 UTC
`my @working;` is the same as `my @working = ();` when `@working` doesn't exist. Once it does, the latter does seem to actually clear the array. Not all. It's already cleared (but not deallocated) at the end of the last pass by the run-time effect of `my`. `my @working = ();` will never result in something different than `my @working;`. (`my @working = () if $x;` is not necessarily the same as `my @working if $x;`, but that code is a buggy to begin with.) Are you confusing `my @working;` with just `@working;`? I noticed you removed the "`my`". Removing the "`my`" is silly. It's not something you should do. At least add this test, please: `'my' => 'my @working; $working[$_] = $_ foreach ( 0...1 +00 );',` [download]	[reply] [d/l] [select]
Re^3: Emptying (and refilling) an array. by JavaFan (Canon) on Jan 12, 2009 at 16:43 UTC
If you want to benchmark explicitely clearing of the array, you should do that - and not start with a "new" array (although, behind the scenes, the array isn't quite new) each time. Move the declaration of the array outside of the loops. Something like: `our @working; cmpthese -20, { one => '@working = (); $working[$_] = $_ foreach 0 .. 100', ... };` [download] Of course, if you're going to fill in all the elements anyway, why bother clearing them?	[reply] [d/l]