One Year With Ruby and Sometimes Still a Newbie

On Rails production performance and monitoring

One Year With Ruby and Sometimes Still a Newbie

Published on May 06, 2008 by eric

I wrote a block of code the other day that had to do with authentication. The use case is that sometimes users authenticate by email and password, and occasionally (in the case of a forgotten password or first login) users can authenticate with a token that is sent via email allowing them to change their password.

So this is what I wrote:

def authenticate(email, password)
  ...
end

def authenticate(token)
  ...
end

and then I tried logging in with an email and password. Oops! The Ruby veterans are out there laughing at me. There is no method overloading in Ruby.

I guess my initial reaction was disbelief. Coming from .NET, overloading methods is something you do just about every day. On one hand, it makes perfect sense not to have the feature in Ruby because method overloading and typing of method arguments are very closely related, but on the the other hand, I am only talking about a variable number of arguments, which has nothing to do with typing.

Here is what I ended up with:

def authenticate(*args)
  if args.size == 1
    ...
  else
    ...
  end
end

It’s not the prettiest of solutions. Here is another way, where args is a hash:

def authenticate(args)
  if args.has_key?(:token)
    ....
  else
    ...
  end
end

#usage
authenticate(:token => 'zA3sDV')
authenticate(:email => 'foo@asdf.com', :password => 'password')

I am definitely thinking that the second way is cleaner. I better get going, I have some code to refactor ;-)

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Continued Discussion

5 responses to this entry

Perhaps it would be lovely and readable for your pseudo-overridden authenticate method directly called one of two specific implementations:

def authenticate(args)
  if args.has_key?(:token)
    authenticate_with_token(args.first)
  else
    authenticate_with_username_password(args[0..1])
  end
end

Dr Nic said:

on May 06, 2008 at 06:37 PM

Since the caller knows what arguments it will be authenticating with, why not just call authenticate_with_token or authenticate_with_username_password directly? Encapsulating the behavior into a single method only adds a layer of complexity.