On each iteration of the loop the (simplified) process is

  1. Allocate memory for @array
  2. Initialize @array
  3. Deallocate memory assigned to @array

Well, I don't know what you mean by "Initialize @array", but otherwise, that's the documented behaviour. And in most cases — including the one you called optimized — it's the observable behaviour.

Perl, however, is not that simple and its loop would be more like

  1. Allocate memory for @array
  2. Initialize @array
  3. Deallocate memory assigned to @array if not referred to else where

No, that's not what it does. For starters, the @array is never deallocated by the loop (or sub).

  1. Allocate memory for @array if it isn't already allocated. (I don't actually know when this is done. It might be earlier.)
  2. When my is executed, put a directive on the stack to clear/free @array.
  3. On stack unwind, in response to the directive, clear the @array if there are no more references to it. Otherwise, allocate a new @array.

In reply to Re^8: references--hard vs anonymous operational weirdness by ikegami
in thread references--hard vs anonymous operational weirdness by hill

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