Ruby:是否可以在模块中定义类方法?

问题描述：

假设有三个类:A、B &C.我希望每个类都有一个类方法，比如 self.foo，它对 A、B 和 B 具有完全相同的代码.C.

Say there are three classes: A, B & C. I want each class to have a class method, say self.foo, that has exactly the same code for A, B & C.

是否可以在模块中定义 self.foo 并将该模块包含在 A、B &C?我尝试这样做，但收到一条错误消息，指出无法识别 foo.

Is it possible to define self.foo in a module and include this module in A, B & C? I tried to do so and got an error message saying that foo is not recognized.

答

module Common
  def foo
    puts 'foo'
  end
end

class A
  extend Common
end

class B
  extend Common
end

class C
  extend Common
end

A.foo

或者，您可以在之后扩展类:

Or, you can extend the classes afterwards:

class A
end

class B
end

class C
end

[A, B, C].each do |klass|
  klass.extend Common
end

Ruby:是否可以在模块中定义类方法?

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