在返回哈希或nil的方法上使用ruby 'or = ' ||=

I have a method that returns a hash, or nil:

我有一个返回哈希或nil的方法:

def person_of_age(age)
  some_hash = @array_of_hashes.select { |h| h.age == age }.last
  return some_hash
end

I want to use this hash like so:

我想用这样的哈希表:

my_height = 170
my_age = 30
if my_height < self.person_of_age(my_age)['height']
 puts "You are shorter than another person I know of the same age!"
end

Now, if the hash returns nil, ruby doesn't like me using ['height']:

现在，如果哈希返回nil, ruby不喜欢我使用['height']:

undefined method `[]' for nil:NilClass (NoMethodError)

Fair enough, but how can I use ||= to avoid this problem? If the method does return nil, let's just say I want the 'height' to be 0.

很好，但是我如何使用||=来避免这个问题?如果这个方法返回nil，我们就说我想要“高度”为0。

I have tried things along the lines of, to no avail:

我已经尝试过了，但没有成功:

if my_height < self.person_of_age(age)||={ 'height' => 0 }['height']
#...
if my_height < self.person_of_age(age)['height'] ||= 0

Clearly my example is running a little thin, and there are other ways around this problem, but if ||= can be used I'd love to know how.

显然，我的例子有点牵强，有其他方法可以解决这个问题，但是如果||=可以使用，我很想知道如何使用。

Thank you!

谢谢你！

3 个解决方案

#1

obvious:

显而易见的:

(self.person_of_my_age(age) || {'height' => 0})['height']

but somehow this does not feel so right

但不知何故，这感觉不太对

#2

You can do it like this:

你可以这样做:

if my_height < self.person_of_age(age).nil? ? 0 : self.person_of_age(age)['height']

Or you can rewrite person_of_age method:

或者可以重写person_of_age方法:

def person_of_age(age)
  some_hash = @array_of_hashes.select { |h| h.age == age }.last || {:height => 0}
  return some_hash
end

or simpler

或者更简单的

def person_of_age(age)
  @array_of_hashes.select { |h| h.age == age }.last || {:height => 0}      
end

#3

I'm not sure if this helps in your circumstance, but one capability Hash has is

我不确定这是否对您的情况有所帮助，但是一个功能散列是。

hash.fetch(key) { block_for_code_evaluated_if_key_absent }

#1