Ruby类方法继承，如何阻止子方法执行？

Question

This question pertains to a Ruby on Rails problem but this simplified problem will give me the solution I am looking for.

I have two classes, the child class is inheriting a parent method, but I want to half the execution of the child method code if certain conditions are met in the parent method.

class A

  def test_method
    puts 'method1'
    return false
  end

end

class B < A

  def test_method
    super
    #return false was called in parent method, I want code to stop executing here
    puts 'method2'
  end

end

b = B.new
b.test_method

And the output is:

method1
method2

My desired output is:

method1

Does anyone know how to achieve my desired output?

Thanks!

Answer 1

You could use simple if-end statement:

class B < A
  def test_method
    if super
      puts 'method2'
    end
  end
end

Now, B#test_method will return false if super returns false . Otherwise it evaluates code inside if-end block.

Answer 2

class B < A
  def test_method
    super and puts 'method2'
  end
end

This way both will run, if super is anything except nil or false

Alternatively, you can use the stronger precedenced && but this lower precedence is often used as flow control.

See Avdi's blog post about this.