Today I Learned

Enumerable Predicate Methods Have a New Argument

Enumerable#grep accepts an argument that returns elements that are true using case equality (===). These elements can then be passed to its block for further proccessing:

fruits = %w(apples orange grapes)
fruits.grep(/s$/) # => ["apples", "grapes"]
fruits.grep(/s$/) { |e| e.start_with?("a") } # => [true, false]

In Ruby 2.5, this parameter argument was added to the Enumerable predicate methods all?, none?, one?, and any?.

fruits = %w(apples orange grapes)
fruit.any?(/s$/) # => true

# === works with more than Regexes!
[1, 3.14, 2ri].all?(Numeric) # => true
[0, 1, 2, 3].all?(1..10) # => false
[0, 5].one?(1..3) # => false
[0, 5].none?(1..3) # => true