But then, when I looked more carefully at the idiom you suggested, there's a subtle bug in: while ( (my $a, @a) = @a ) {". I realized it doesn't, in fact, reasign most of @a to iteslf every time, because you're declaring my @a (along with my $a), so it's a different @a that you're doing the assignment to! Also, when you run it, you get an infinite loop:

You are talking about the code I wrote, but the code you actually tested is very different. There is a big difference between

(my $a, @a) = @a
[download]

and

my ($a, @a) = @a
[download]

In the first case, only $a is redeclared with my. The @a variable is the same one on both sides. In the second case, both $a and @a are redeclared with my. Notice that in my reply, I used the first one. There is no infinite loop, and it really does work like I described.

So for now, I'll stick with the "while (defined($a = shift @a))" syntax.

Again, this will fail if there is an undef in the array. You can't get undef from <$fh> unless it's the end of the file, so it is safe to test the result of <$fh> for undef. But it is perfectly reasonable to have undef as a value in an array (and not be at the end of the array).

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