Question

I am an RoR newbie. I have created a small application in ruby which has small functions to execute the code.

e.g.

 def abc(xyz)
    some code
 end

 def ghi(xyz)
    some code
 end

 def jkl(output)
    some code
 end

 xyz = abc[ARGV(0)]
 output = ghi(xyz)
 puts jkl(output)

Now, when I run this code in command prompt using ruby .rb, it executes nicely and returns the desired results. But when I try to create a class and add this whole code to it e.g.

 class Foo
     def abc(xyz)
    some code
 end

 def ghi(xyz)
    some code
 end

 def jkl(output)
    some code
 end

 xyz = abc[ARGV(0)]
 output = ghi(xyz)
 puts jkl(output)
 end

It generates the error like “undefined method ‘abc’ for Foo:Class (NoMethodError)”

All I want to ask is that how shall I add this code to a class so that it can become more pluggable and get the desired results.

Thanks in advance.

Answer 1

As this is written, these are all instance methods. You need to make them class methods like these two examples, or you could leave them as is and create an instance of the class. Either way, you should probably move the last three statements outside the class definition.

class Foo
  class << self
    def abc(xyz)
      some code
    end

    def ghi(xyz)
      some code
    end

    def jkl(output)
      some code
    end
  end
end
xyz = Foo.abc('something')
output = Foo.ghi(xyz)
puts Foo.jkl(output)

OR….

class Foo
  def self.abc(xyz)
    some code
  end

  def self.ghi(xyz)
    some code
  end

  def self.jkl(output)
    some code
  end
end
xyz = Foo.abc('something')
output = Foo.ghi(xyz)
puts Foo.jkl(output)

EDIT: To answer your question in the comments, this is how you would instantiate the class and call using instance methods.

class Foo
  def abc(xyz)
    some code
  end

  def ghi(xyz)
    some code
  end

  def jkl(output)
    some code
  end
end
bar = Foo.new
xyz = bar.abc('something')
output = bar.ghi(xyz)
puts bar.jkl(output)

If you don’t have any Ruby learning materials yet, you might want to check out Chris Pine’s tutorial, which includes a section on classes and how they work. As for books, here is a great book for Ruby in general and here is a question regarding books for Rails. I would suggest getting a decent grasp of Ruby before getting too deep into Rails.