Dependency Inversion Principle

inversion.rb

# Violation of the Dependency Inversion Principle in Ruby
# The class Printer depends on classes PdfFormatter and HtmlFormatter which are low-level objects
class Printer
  def initialize(data)
    @data = data
  end

  def print_pdf
    PdfFormatter.new.format(@data)
  end

  def print_html
    HtmlFormatter.new.format(@data)
  end
end

class PdfFormatter
  def format(data)
    # format data to Pdf logic
  end
end

class HtmlFormatter
  def format(data)
    # format data to Html logic
  end
end



#Correct use of the Dependency Inversion Principle in Ruby
#Refactor Printer class by ensuring the printer ‒ a high-level object 
#doesn’t depend directly on the implementation of low-level objects ‒ the PDF and HTML formatters

class Printer
  def initialize(data)
    @data = data
  end

  def print(formatter: PdfFormatter.new)
    formatter.format(@data)
  end
end

class PdfFormatter
  def format(data)
    # format data to Pdf logic
  end
end

class HtmlFormatter
  def format(data)
    # format data to Html logic
  end
end