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  • The pointers to the scalars placed on the stack. But that has to happen no matter the interface.

I believe LanX's performance concern is whether a hash with 100,000 elements must extend the perl stack to 200,000 elements before beginning the loop. It's not a guaranteed implementation detail since, as I recall, for (1..100_000) is optimized to use a counter and repeatedly modify a scalar rather than generating 100_000 distinct scalars at once.

So I think I'm hearing that yes it does need to allocate the perl stack to 200_000 elements, and does not perform some fancy optimized use of 'each'.

Also I would not say that "it uses the built-in iterator" unless it picks up from the current position of the internal iterator, rather than from the start of the hash. @foo= %bar always gives you the full contents of %bar, but while (my @x= each %bar) { push @foo, @x; } could omit elements if a previous 'each' iteration left off in the middle.

In reply to Re^9: Why does each() always re-evaluate its argument? ("for_list" ) by NERDVANA
in thread Why does each() always re-evaluate its argument? by Darkwing

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