ruby Array.empty 的相反方法是什么？或 [].empty？红宝石
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What is the opposite method of Array.empty? or [].empty? in ruby
提问by Kamilski81
I do realize that I can do
我确实意识到我可以做到
unless [1].empty?
But I'm wondering if there is a method?
但我想知道是否有方法？
回答by noodl
As well as #any?as davidrac mentioned, with ActiveSupportthere's #present?which acts more like a truth test in other languages. For nil, false, '', {}, []and so on it returns false; for everything else true (including 0, interestingly).
除了#any?提到的davidrac 之外，ActiveSupport还有#present？这更像是其他语言的真实测试。对于nil、false、''、 等{}，[]它返回 false；对于其他一切都是真的（包括 0，有趣的是）。
回答by davidrac
You may use [1].any?, which is actually defined in Enumerable
您可以使用[1].any?，它实际上是在Enumerable 中定义的
Note that this will not work in case your array hold only nil or false values (thanks for the comment @InternetSeriousBusiness).
请注意，如果您的数组仅包含 nil 或 false 值，这将不起作用（感谢@InternetSeriousBusiness 的评论）。
回答by Rod McLaughlin
[nil].any?
=> false
[nil].any? {|something| true}
=> true
[].any? {|something| true}
=> false
[false, false].any? {|something| true}
=> true
[nil, 'g'].any? {|something| true}
=> true
回答by CRandER
No single method I know of is going to give you that in Ruby. Key word 'single':
我所知道的任何一种方法都不会在 Ruby 中为您提供这种方法。关键词“单身”：
[5].size.positive? => true
[5].size.nonzero? => 1
[].size.positive? => false
[].size.nonzero? => nil
Both of these are even more useful with the safe navigation operator, since nil returns falsy, meaning negative methods (like #empty?) break down a bit:
这两个对于安全导航操作符更有用，因为 nil 返回假，意味着否定方法（如#empty？）有点分解：
# nil considered 'not empty' isn't usually what you want
not_empty = proc{|obj| !obj&.empty? }
not_empty.call nil => true
not_empty.call [ ] => false
not_empty.call [5] => true
# gives different 3 answers for the 3 cases
# gives truthy/falsy values you'd probably expect
positive_size = proc{|obj| obj&.size&.positive? }
positive_size.call nil => nil
positive_size.call [ ] => false
positive_size.call [5] => true
# gives truthy/falsy values you'd probably expect
nonzero_size = proc{|obj| obj&.size&.nonzero? }
nonzero_size.call nil => nil
nonzero_size.call [ ] => nil
nonzero_size.call [5] => 1
回答by vidur punj
To check for elements in array :
.empty?
.present?
检查数组中的元素：
.empty？
。展示？
if a={}
a.any? .nil?
will gives you false.
如果 a={}
a.any? 。零？
会给你假的。
To check whether or not a field has a non-nil value:
要检查字段是否具有非 nil 值：
.present?
.nil?
.any?
