Rails optional argument

It’s as simple as this:

class Person
    attr_accessor :name, :age

    def initialize(name="", age = 0)
        self.name = name
        self.age = age
    end
end


Person.new('Ivan', 20)
Person.new('Ivan')

However, if you want to pass only age, the call would look pretty ugly, because you have to supply blank string for name anyway:

Person.new('', 20)

To avoid this, there’s an idiomatic way in Ruby world: options parameter.

class Person
    attr_accessor :name, :age

    def initialize(options = {})
        self.name = options[:name] || ''
        self.age = options[:age] || 0
    end
end

Person.new(name: 'Ivan', age: 20)
Person.new(age: 20)
Person.new(name: 'Ivan')

You can put some required parameters first, and shove all the optional ones into options.

Edit

It seems that Ruby 2.0 will support real named arguments.

def example(foo: 0, bar: 1, grill: "pork chops")
  puts "foo is #{foo}, bar is #{bar}, and grill is #{grill}"
end

# Note that -foo is omitted and -grill precedes -bar
example(grill: "lamb kebab", bar: 3.14)