SPUG: "Clobberation" in ($c,$d)=($d,$c)

[Brian Ingerson]

Daniel Chetlin wrote:
> 
> During the Q&A session at the Perligata meeting, someone mentioned that
> if you alias a variable and then use it on one side of a variable
> switch, you get "clobberation". I was thinking about that tonight and
> decided to take a look, but I couldn't reproduce it.
> 
> If memory serves, the problem was with constructs like:
> 
>   *e = \$c;
>   ($c, $d) = ($d, $e);
> 
> But that seems to work fine, so I must be remembering wrong. Can someone
> refresh my memory?

What Damian wrote on the board was not exactly what was needed to
produce the problem, just the basic idea. Try this:

(*c1, *d1) = (\$c, \$d);
($c, $d) = (10, 20);
($c, $d) = ($d1, $c1);
print "$c, $d\n";

The result should be perfectly clear :)

Brian

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