How can I intercept method call in ruby?

by

This is one way to do it:

class Superclass
  def before_each_method name
    p [:before_method, name]
  end

  def self.method_added name
    return if @__last_methods_added && @__last_methods_added.include?(name)
    with = :"#{name}_with_before_each_method"
    without = :"#{name}_without_before_each_method"
    @__last_methods_added = [name, with, without]
    define_method with do |*args, &block|
      before_each_method name
      send without, *args, &block
    end
    alias_method without, name
    alias_method name, with
    @__last_methods_added = nil
  end
end

class SubclassA < Superclass
  def my_new_method
    p :my_new_method
  end

  def my_new_other_method
    p :my_new_other_method
  end
end

SubclassA.new.my_new_method
SubclassA.new.my_new_other_method

This will create a wrapper method using the alias_method_chaining method as soon as the method you’d like to wrap is defined in the subclass.

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