In Ruby is there a way to overload the initialize constructor?

by

The answer is both Yes and No.

You can achieve the same result as you can in other languages using a variety of mechanisms including:

  • Default values for arguments
  • Variable Argument lists (The splat operator)
  • Defining your argument as a hash

The actual syntax of the language does not allow you to define a method twice, even if the arguments are different.

Considering the three options above these could be implemented with your example as follows

# As written by @Justice
class Person
  def initialize(name, lastName = nil)
    name = name + " " + lastName unless lastName.nil?
    @name = name
  end
end


class Person
  def initialize(args)
    name = args["name"]
    name = name + " " + args["lastName"] unless args["lastName"].nil?
    @name = name
  end
end

class Person
  def initialize(*args)
    #Process args (An array)
  end
end

You will encounter the second mechanism frequently within Ruby code, particularly within Rails as it offers the best of both worlds and allows for some syntactic sugar to produce pretty code, particularly not having to enclose the passed hash within braces.

This wikibooks link provides some more reading

More Related Contents:

  1. What is attr_accessor in Ruby?
  2. How to pass command line arguments to a rake task
  3. Parsing a JSON string in Ruby
  4. How to set TLS context options in Ruby (like OpenSSL::SSL::SSL_OP_NO_SSLv2)
  5. Ruby: kind_of? vs. instance_of? vs. is_a?
  6. Why does installing Nokogiri on Mac OS fail with libiconv is missing?
  7. Pass variables to Ruby script via command line
  8. Cannot call non W3C standard command while in W3C mode (Selenium::WebDriver::Error::UnknownCommandError) with Selenium ChromeDriver in Cucumber Ruby
  9. What is the difference between Ruby 1.8 and Ruby 1.9
  10. Is there a reason that we cannot iterate on “reverse Range” in ruby?
  11. How does “(1..4).inject(&:+)” work in Ruby
  12. Is sort in Ruby stable?
  13. Open an IO stream from a local file or url
  14. Installing RubyGems in Windows
  15. Comparing ruby hashes [duplicate]
  16. How can I capture STDOUT to a string?
  17. Using WWW:Mechanize to download a file to disk without loading it all in memory first
  18. Set global default encoding for ruby 1.9
  19. What do you call the -> operator in Ruby?
  20. Understanding Ruby’s load paths
  21. Why is this RMagick call generating a segmentation fault?
  22. git, Heroku: pre-receive hook declined
  23. Understanding private methods in Ruby
  24. What is the difference between STDIN and $stdin in Ruby?
  25. Iterate through every file in one directory
  26. Why isn’t self always needed in ruby / rails / activerecord?
  27. Ruby: extend self
  28. How to make Sinatra work over HTTPS/SSL?
  29. ERROR: Error installing ffi: ERROR: Failed to build gem native extension
  30. What is the opposite of string.next?

Leave a Comment