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  $name = $user[$idx]  -> {'name'};     # may create a hash
  $name = $user[$idx] ?-> {'name'};     # leaves @user alone
  $name = $person  -> name;             # chokes on undef
  $name = $person ?-> name;             # passes undef on

 
# If velocity is defined, use it, otherwise don't.
# Note that just the concatenation arg is guarded,
...
# so a nonexistent 'parent' component would be created.

$c = $d^^ ->{'parent'}->{'name'};

# these two are equivalent:
$a = foobar($b^^);
...

# this would be safer:
$a = defined($b)? foobar($b): undef;

$f = ($g | $h^^ | $i)^^ & $j;

# these two are equivalent:
$a =              $b . $c^^;
$a = defined($c)? $b . $c: undef;

# these two are equivalent:
$a =         foo() ?? bar();
$a = defined(foo())?  bar(): undef;

$a = "hello $b";       # may trigger a warning
$a = "hello $b^^";     # does not help
$a = 'hello ' . $b^^;  # may evaluate to undef

$a = $b^^++;        # error
$a = $b++^^ * $c;   # ok
$a = ++$b^^ * $c;   # ok but pointless