Hello Perl Monks

This is my first question here, so please don't laugh.

Can anyone explain to me what's going on in this code? 

#!/usr/bin/perl
use strict;
use warnings;
sub foo ($) {
    my $x = shift;
    print "foo gets '$x'\n";
    return ($x+2, 33);
}
my @a = foo(42);   
print "a=@a\n";   
@a = sort(foo(42)); 
print "a=@a\n";  
@a = (sort foo(42));  
print "a=@a\n";    
@a = sort foo(42);  
print "a=@a\n";

[download]
which produces the following output on my Linux system with Perl 5.10.1: 
foo gets '42'
a=44 33
foo gets '42'
a=33 44
a=42
a=42

[download]

If I use old-style subs (i.e. &foo instead of foo), then it produces 'a=33 44' three times, which is what I'd expect.

In reply to New-style sub strangeness by ChrisDennis

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