Ruby 中是否可以像 PHP 中那样自动初始化多维哈希数组?
我已经习惯了在 PHP 中使用多维数组,我可以通过
unset($a); // just to show that there is no variable $a
$a['settings']['system']['memory'] = '1 Gb';
$a['settings']['system']['disk space'] = '100 Gb';
Is there a way to do those in Ruby? 来分配和初始化哈希?或者我需要先初始化所有维度,然后再赋值。是否可以定义一个高级哈希来执行我需要的操作?你会怎么做?
更新
除了Douglas提出的解决方案(见下文)之外,我还找到了关于该主题的线程,其中 Brian Schröäer 提出了 Hash
类的扩展:
class AutoHash < Hash
def initialize(*args)
super()
@update, @update_index = args[0][:update], args[0][:update_key] unless args.empty?
end
def [](k)
if self.has_key?k
super(k)
else
AutoHash.new(:update => self, :update_key => k)
end
end
def []=(k, v)
@update[@update_index] = self if @update and @update_index
super
end
end
它可以解决问题当仅请求项值时意外创建丢失的哈希项时,例如a['key']
。
一些其他参考
I am so used to work in PHP with multi-dimensional arrays, where I can assign and initialize a hash by
unset($a); // just to show that there is no variable $a
$a['settings']['system']['memory'] = '1 Gb';
$a['settings']['system']['disk space'] = '100 Gb';
Is there a way to do similar thing in Ruby? Or I need to initialize all dimensions first, and then to assign values. Is it possible to define an advanced Hash which will allow to do what I need? How would you do that?
Update
In addition to the solution proposed by Douglas (see below), I have found a thread on the subject, in which Brian Schröäer has proposed an extension for the Hash
class:
class AutoHash < Hash
def initialize(*args)
super()
@update, @update_index = args[0][:update], args[0][:update_key] unless args.empty?
end
def [](k)
if self.has_key?k
super(k)
else
AutoHash.new(:update => self, :update_key => k)
end
end
def []=(k, v)
@update[@update_index] = self if @update and @update_index
super
end
end
It allows to solve the problem when a missing hash item is undesirably created when the item value was only requested, e.g. a['key']
.
Some additional references
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试试这个:
如果键不存在,则块的结果将用作默认值。在这种情况下,默认值也是一个散列,它使用散列作为其默认值。
Try this:
If the key doesn't exist, then the result of the block will be used as the default value. In this case, the default value is also a hash which uses hashes as its default values.