ruby keyword arguments of method

Question

How can I declare a method with keyword arguments just like rails do. some examples may be

Person.find(:all, :conditions => "..."). 

How can I use symbols to create methods similar to the above?

I am very new to ruby. Thanks in advance!

Answer 1

Ruby doesn't actually have keyword arguments. Rails is exploiting a feature of Ruby which lets you omit the braces around a hash. For example, with find, what we're really calling is:

Person.find(:all, { :conditions => "...", :offset => 10, :limit => 10 } )

But if the hash is the last argument of the method, you can leave out the braces and it will still be treated as a hash:

Person.find(:all, :conditions => "...", :offset => 10, :limit => 10)

You can use this in your own methods:

def explode(options={})
    defaults = { :message => "Kabloooie!", :timer => 10, :count => 1 }
    options = defaults.merge(options)

    options[:count].times do
        sleep options[:timer]
        puts options[:message]
    end
end

And then call it:

explode :message => "Meh.", :count => 3

Or call it without an argument, resulting in all default values being used:

explode

Answer 2

Since Ruby 2.0, ruby does have keyword arguments.

def my_method(arg1, name: 'defaultName', number: 0)
  puts arg1, name, number
end