Question

Is it possible to use the method open on my Parser class? It seems that the method is conflicting with IO::open?

class Parser
    require 'nokogiri'

    def parse
        doc = open "someFile.html"
        # Get to parsin' ...
    end 

    def open str
        Nokogiri::HTML(open(str))
    end 
end 

parser = Parser.new
parser.parse

When I run the script I get this error:

$ ruby parser.rb
parser.rb:10: stack level too deep (SystemStackError)

I’ve tried a variety of things, but the only thing that seems to work is to rename Parser::open to something other than open, like docopen

I’m trying to understand how ruby works, so any further explanation beyond the answer is greatly appreciated!

Answer 1

open is a method on the module Kernel that is included in Object the parent class of all Ruby classes. What happens is that open(str) in

class Parser

  def open str
    Nokogiri::HTML(open(str))
  end

is calling your defined open method on Parser recursively. If you change your method to

  def open str
    Nokogiri::HTML(Kernel.open(str))
  end

you’ll call the open method on Kernel as intended.