大伙儿很有兴趣，再来一题，6yku。
We have an awesome, custom collection class, Bag, which already has implemented an #each for traversing its items and #count for counting the items. New requirements come in for the project to check arbitrary conditions regarding data inside of a Bag.
We were just about to break out the trusty old #each hammer, when we realize there might be an better/easier/cleaner way. Spotting an abstraction waiting to happen, we decide implement a new method, #every?, to make sure that every item in a Bag matches the condition.
The #every? method needs to receive a block to run some test against every item. If every test passes, it returns true. If any of the tests fail, it returns false. Empty bags should pass all tests.
It also has a shorthand variation for our lazy friends. If you do not pass a block to #every, it tests the truthiness of the items themselves.
class Bag
# already implemented:
# #each
# #count
Examples:
bag = Bag.new(:surefire, :tests)
bag.every? { true } # => true
bag.every? { false } # => false
bag = Bag.new(1,2,3,4)
bag.every? { |num| num > 0 } # => true
bag.every? { |num| num.odd? } # => false
bag = Bag.new(:code, :wars)
bag.every? # => true
bag = Bag.new(:cat, :+, :roomba, nil, :profit!)
bag.every? # => false
反正已经出过一次洋相了不介意再出一次...
def every?
self.each do |item|
if block_given?
return false unless yield item
else
return false unless item
end
end
true
end
#1 楼 @blacktulip 谢谢，学习了。
def every?
each do |item|
return false unless block_given? ? yield(item) : item
end
return true
end
这个思路类似
