class 的范围猴子修补

Question

我需要修补 class，但希望修补程序是某些模块的本地修补程序。在 Ruby 我会做：

module ArrayExtension
  refine Array do
    def ===(other)
      self.include?(other)
    end
  end
end

module Foo
  using ArrayExtension
  def self.foo
    case 2
    when [1,2] then puts "bingo!"
    end
  end
end

Foo.foo          # => bingo!
puts [1,2] === 2 # => false

Crystal中有类似的东西吗？

Answer 1

所以要重新定义 === 你只需重新定义它即可。

module Foo
  def ===(other)
    self.includes?(other)
  end
end

class CustomArray(T) < Array(T)
  include Foo
end

custom_array = CustomArray(Int32).new

custom_array << 1
custom_array << 2

puts custom_array === 1 # true
puts custom_array === 2 # true
puts custom_array === 3 # false

class 的范围猴子修补

Scoped monkey-patching of a class

scope

refinements

crystal-lang