Undocumented variable?

[dpmott]

So, I was quickly coding up a proof-of-concept script today, and I fat-fingered a line that was supposed to check the $@ variable. However, the compiler didn't catch my use of the undocumented global array @$. So I wrote some test code:

#!perl
use strict;           # need to pre-declare variables...
@$ = (1, 2, 3, 4);    # I wonder what this is?
eval { die "blah"; }; # This sets $@
print join(', ', @$); # prints '1, 2, 3, 4'

Could someone please tell me what the @$ array is, what it's used for, and/or why the compiler doesn't warn or die when I use it? It's not documented in perlvar or any reference material that I have. One of my co-workers speculated that the implementation probably reserved the glob of '$' variables, since there's the '$$' variable...

I don't mind if I get dyslexic with '$$', but '@$' should be some kind of compile-time error, IMHO.

Unless it's actually used for something? Anyone?

Thanks,
-dpmott