gistfile1.rb

# in a simple case, I wish rails worked like this

messages = order.validate # returns errors array

if messages.empty?
  order.save!
  render 'show'
else
  flash[:errors] = messages
  render 'edit'
end


# with more complex cases, I would do something like your order.pay method, with even more complex cases 
# I would bust out a PayOrder use case controller.

# I don't think 4c is "bad" by any stretch of the imagination. But if you can get away with the null object pattern, 
# I think using return values make tracing the code more clear. If you are looking at a function that returns a value, 
# you know exactly where execution resumes. If you look at a function that raises, it gets more complecated :)

# On a side note, I don't agree with 2, unless it is in very simple cases. I think the domain model should be an 
# abstract representation that is used by use case controllers (or play DCI roles) to do things. Fat models end up with 
# giant classes with super complex interactions, DCI/Use case controllers tend to make understanding how things work much 
# easier, since coordination logic doesn't get spread out across multiple classes/files.