Question

Working with the Ruby Gem ‘Mail’, I am confused as to how variables are able to be stored without initializing an object? For example:

Mail.defaults do
  retriever_method :pop3, :address    => "pop.gmail.com",
                          :port       => 995,
                          :user_name  => '<username>',
                          :password   => '<password>',
                          :enable_ssl => true
end

After which you are able to call methods such as Mail.first and have it return the first message in the mailbox with the configured defaults.

I realize everything in Ruby is an object, even a class, so when require 'mail' is called, does an object containing the the class Mail actually get created and mad available to the program? What exactly is happening here?

Answer 1

The contents of mail.rb are loaded into the file that has the require 'mail' statement.

After having a look in the gem, mail.rb contains the Mail module, which in turn contains many other require statements.

mail.rb

module Mail
  ## skipped for brevity

  # Finally... require all the Mail.methods
  require 'mail/mail'
end

mail/mail.rb

module Mail
  ## skipped for brevity

  # Receive the first email(s) from the default retriever
  # See Mail::Retriever for a complete documentation.
  def self.first(*args, &block)
    retriever_method.first(*args, &block)
  end
end

So then the methods are made available to your program.