add the same code in multiple methods

Question

I have a class that has N methods.

class MyClass
  def self.method_one(params)
    #specific code
  end

  def self.method_two(params)
    #specific code
  end
end

I need to add the same code for each method created in that class. I need to put the code between "begin and rescue"

I tried the following, but I did not succeed:

class MyClass < BaseClass
  add_rescue :method_one, :method_two, Exception do |message|
    raise message                                                     
  end

  def self.method_one(params)
    #specific code
  end

  def self.method_two(params)
    #specific code
  end
end

I created a method to change the methods

class BaseClass
  def self.add_rescue(*meths, exception, &handler)
    meths.each do |meth|
      old = instance_method(meth)
      define_method(meth) do |*args|
        begin
          old.bind(self).call(*args)
        rescue exception => e
          handler.call(e)
        end
      end
    end
  end
end

I always get the error message: undefined method `method_one 'for Myclass: Class

Sidenote: even if this worked, you discard the block that might be passed to the method in your wrapper. — Aleksei Matiushkin
– Aleksei Matiushkin, Commented Jun 15, 2018 at 12:58

Aleksei Matiushkin · Accepted Answer · 2018-06-15 13:00:41Z

3

MyClass#method_one is a class method or, in other words, the instance method of MyClass.singleton_class. That said, we can Module#prepend the desired functionality to MyClass.singleton_class:

def self.add_rescue(*meths, exception, &handler)
  mod =
    Module.new do
      meths.each do |meth|
        define_method meth do |*args, &λ|
          begin
            super(*args, &λ)
          rescue exception => e
            handler.(e) 
          end
        end
      end
    end

  MyClass.singleton_class.prepend(mod)
end

edited Jun 15, 2018 at 13:00

answered Jun 15, 2018 at 12:55

Aleksei Matiushkin

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