From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-10-13T23:04:10+09:00
Subject: Re: Options in a class

On Wed, Oct 13, 2010 at 3:46 PM, Andrew Wagner <wagner.andrew@gmail.com> wrote:
> Try this:
> module Abc
>  def self.test(arg => :red)
>    puts arg
>  end
> end
>
> puts Abc.test # => red
> puts Abc.test(:blue) #=> blue

The above should be '=', not '=>'. Like this:

irb(main):010:0> module Abc
irb(main):011:1> def self.test(color = :red)
irb(main):012:2> puts color
irb(main):013:2> end
irb(main):014:1> end
=> nil
irb(main):015:0> Abc.test
red
=> nil
irb(main):016:0> Abc.test(:blue)
blue
=> nil

As you mentioned "options", it seems that you might want to allow
passing several options, not just one argument. The usual idiom for
that is using a hash:

irb(main):017:0> module Abc
irb(main):018:1> def self.test(options = {})
irb(main):019:2> color = options[:color] || :red
irb(main):020:2> size = options[:size] || 3
irb(main):021:2> puts color,size
irb(main):022:2> end
irb(main):023:1> end
=> nil
irb(main):024:0> Abc.test
red
3
=> nil
irb(main):025:0> Abc.test(:color => :blue)
blue
3
=> nil
irb(main):027:0> Abc.test(:color => :blue, :size => 5)
blue
5
=> nil

You could also have the default values in the default argument:

def self.test(options = {:color => :red, :size => 3})

or like this:

def self.test(options = {})
options = {:color => :red, :size => 3}.merge(options)
end

Jesus.