Creating a function in ruby

Question

I have some problem creating a function for my Rails application.

I want it to work as follows:

str = "string here"
if str.within_range?(3..30)
puts "It withing the range!"
end

To do this, I added this to my application helper:

def within_range?(range)
  if self.is_a?(String)
    (range).include?(self.size)
  elsif self.is_a?(Integer)
    (range).include?(self)
  end
end

I get this error:

undefined method `within_range?' for "":String

Does anyone know what the problem is?

Answer 1

Hello, I have a problem creating a function for my Rails application.

Uh, right there we come across our first misunderstanding: Ruby is not a functional programming language. It is an object oriented programming language. There is no function like function in Ruby. Ruby only uses methods that live on classes.

str = 'string here'
puts "It within the range!" if str.within_range?(3..30)

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def within_range?(range)
  if is_a?(String)
    range.include?(size)
  elsif is_a?(Integer)
    range.include?(self) 
  end
end

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class Object
  def within_range?(range)
    if    is_a?(String)  then range.include?(size)
    elsif is_a?(Integer) then range.include?(self) end
  end
end

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  def within_range?(range)
    case self
    when String  then range.include?(size)
    when Integer then range.include?(self) end
  end
end

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class String
  def within_range?(range)
    range.include?(size)
  end
end

class Integer
  def within_range?(range)
    range.include?(self)
  end
end

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# => NoMethodError: undefined method `within_range?' for []:Array

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Answer 2

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: Rubys Mixins Rails Java Framework

Answer 3

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class Object
  def within_range?(range)
    if is_a?(String)
      (range).include?(size)
    elsif is_a?(Integer)
      (range).include?(self)
    end
  end
end

Answer 4

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def within_range?(obj, range)
  case obj
  when String  then range.include?(obj.size)
  when Integer then range.include?(obj)
  end
end

:

str = "string here"
puts "'#{str}' is within the range!" if within_range?(str, 3..30)

Answer 5

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class String
 def within_range?(range)
  if self.is_a?(String)
    (range).include?(self.size)
  elsif self.is_a?(Integer)
    (range).include?(self)
  end
 end
end