Perl中可以使用什么样的语法糖来减少l / rvalue运算符的代码与if语句？

有一堆,因为Perl是一个漂亮的含糖语言,但是使用任何语言中最常用的语句是if语句和设置值的组合.我想我已经找到了很多,但还是有一些差距.最终,目标是不必多次写入变量名称：

这是我到目前为止

$r ||= $s;          # $r = $s unless ($r);
$r //= $s;          # $r = $s unless (defined $r);
$r &&= $s;          # $r = $s if ($r);
$r = $c ? $s : $t;  # if ($C) { $r = $s } else { $r = $t }
$c ? $r : $s = $t;  # if ($C) { $r = $t } else { $s = $t }
$r = $s || $t;      # if ($s) { $r = $s } else { $r = $t }
$r = $s && $t;      # if ($s) { $r = $t } else { $r = $s = undef,untrue,etc. }
$c and return $r;   # return $r if ($c);
$c or  return $r;   # return $r unless ($c);
$c and $r = $s;     # $r = $s if ($c);
@$r{qw(a b c d)}    # ($r->{a},$r->{B},$r->{C},$r->{D})

有人也有一个really interesting article在一个“秘密操作符”,如下所示：

@H_904_4@my @part = ( 'http://example.net/app',( 'admin' ) x!! $is_admin_link,( $subsite ) x!! defined $subsite,$mode,( $id ) x!! defined $id,( $submode ) x!! defined $submode,);

但是,我发现从列表中缺少的是：

$r <= $s;                 # read as "$r = min($r,$s);" except with short-circuiTing
$r = $s if (defined $s);  # what's the opposite of //?
$r and return $r          # can that be done without repeaTing $r?

还有什么值得添加的吗？什么其他条件集变量可用来减少代码？还有什么缺点？

$c and return $r;    # return $r if ($c);
$c or return $r;     # return $r unless ($c);
$c and $r = $s;      # $r = $s if ($c);

$var = $new_value if Defined $new_value;

defined and $var = $_ for $new_value;

$foo = "[$foo]";
$bar = "[$bar]";

$_ = "[$_]" for $foo,$bar;