perl - 将属性重置为默认值

Question

我可以像这样用 Moose 声明一个属性：

has 'attr' => (is => 'rw', isa => 'Int', default => 10);

是否可以将此值重置为默认值？

例子：

$obj->attr(5); # sets attr to 5
$obj->_reset_attr;
print $obj->attr; # will print 10

Answer 1

如果你这样做：

has 'attr' => (
  is => 'rw',
  isa => 'Int',
  lazy => 1,
  default => 10,
  clearer => '_clear_attr',
);

那么你可以这样做：

my $obj = Class->new;
print $obj->attr; # 10
$obj->attr(5);
print $obj->attr; # 5
$obj->_clear_attr;
print $obj->attr; # 10

lazy和的组合在clearer这里很重要。