In my attempts to write more efficient code, i have come up with a few situations where i dont understand exactly what Perl is doing, and thus can't decide which way to code something for faster execution.

Basically i am trying to figure out when a function is called, and then exited, what sticks around for subsequent calls, and what is destroyed and needs to be recreated internally on each call. 

# case 1
sub blah {
   ...
   my @list = qw(# list of things);
   foreach my $item (@list) {
   ...
}

# case 2
{
   my @list;
   BEGIN {
      @list = qw(# list of things);
   }
   sub blah {
      ...
      foreach my $item (@list) {
      ...
   }
}

# case 3
sub blah {
   ...
   foreach my $item qw(# list of things) {
   ...
}

[download]
I'm assuming that @list is not going to ever change in blah().

In case 1, im pretty sure that @list is re-initialized on each call to blah()

In case 2, @list is initialized once, in the BEGIN{}, and never goes away, because of the closure.

case 3, i am not sure what happens. Does the inline list re-create itself on each call to blah(), or is it created once and sticks around somewhere? I'm uncertain about this one because the list is never assigned to a variable (as a whole), which makes me think that its sticking around somewhere.

I could ask similar questions about inlined regexs, etc.

UPDATE:
changed my blah {} to sub blah {} - as it should be.

In reply to Resource allocation question by shemp

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