如何从Ruby模块中仅导入几个函数？

Question

假设我有一个带有方法的模块:function1,function2,function3.我想导入function1和function2但不导入function3.有没有办法在红宝石中做到这一点？

Answer 1

不确定是否有一种干净的方法来添加所需的方法,但您可以通过使用删除不需要的方法undef_method.

module Foo
  def function1
  end

  def function2
  end

  def function3
  end
end

module MiniFoo
  include Foo
  not_wanted_methods = Foo.instance_methods - %w(function1 function2)
  not_wanted_methods.each {|m| undef_method m}
end

class Whatever
  include MiniFoo
end

Answer 2

类似的解决方案,但更自动.我不知道会发生什么样的奇怪事情.

module Foo
  def m1
    puts "Hello from m1"
  end

  def m2
    puts "Hllo from m2"
  end
end

class Module
  alias :__include__ :include
  def include(mod, *methods)
    if methods.size > 0
        tmp  = mod.dup
        new_mod = Object.const_set("Mod#{tmp.object_id}", tmp)
        toremove = new_mod.instance_methods.reject { |m| methods.include? m.to_sym }
        toremove.each { |m| new_mod.send(:undef_method, m) }
        __include__(new_mod)
    else
      __include__(mod)
    end
  end
end

class Bar
  include Foo
end

class Baz
  include Foo, :m2
end

bar = Bar.new
baz = Baz.new
p bar.methods - Object.methods
p baz.methods - Object.methods

=>

["m1", "m2"]
["m2"]

Answer 3

假设您控制模块的源代码,我认为最干净的方法是将模块拆分为更多,呃,模块化的部分.

如果你只想要一个模块的某些部分,这是一个非常好的迹象,你可以将该模块重构为多个负责较少的模块.