CODEWITHSUNDEEP
rubycoding-style
daremkd
daremkd

Reputation: 8424

Public method with methods defined inside vs. private

Suppose I have

class SomeClass
  def some_public_method
    method_1
    method_2
  end

where method_1 and method_2 won't be used by anything except some_public_method.

They can be defined inside that method:

class SomeClass
  def some_public_method
    def method_1
      p 'hi'
    end
    def method_2
      p 'there'
    end
    method_1
    method_2
  end
end

or defined separately as private ones in the class. I was wondering which approach will be easier to maintain in the future and why (should these methods "belong" to some_public_method and not created unless some_public_method is created or they should belong to the class). I think this question isn't opinion-based because of the why part. Please provide examples of how some other code might conflict with either of these two approaches to prove your point on why either approach is better for more maintainable code.

Upvotes: 1

Views: 63

Answers (1)

BroiSatse
BroiSatse

Reputation: 44685

There are no such a thing as nested methods in ruby, but you can write methods which define new methods. By doing this:

class SomeClass
  def some_public_method
    def method_1
      p 'hi'
    end

    def method_2
      p 'there'
    end

    method_1
    method_2
  end

end

Methods method_1 and method2 are not defined just after class is declared, because their definitions has not been executed. As soon as you execute some_public_method, those definitions are executed and both methods are added to the class. Whether they are public or private depends on whether methods private, protected or public (Yep, those are methods) has been executed against the class or not. If none of those methods has been executed, they are public.

s = SomeClass.new
t = SomeClass.new

s.method_1     #=> undefined method error
t.some_public_method
s.method_1     #=> hi

If you run some_public_method again, those methods will be redefined which may result in a warning.

In short, do not nest method definitions, unless you are going for some nice metaprograming feature. Even then it is probably better to use define_method method.

Upvotes: 2

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