What is a def ... else ... end construct?

Question

I have this code:

def with_else
  puts 'we enter something funny'
  if true
    puts "yes"
    'return YES'
  end
  'return what?'
else
  puts 'no'
  'return else -> no'
end

puts with_else

and the output is this:

we enter something funny
yes
no
return else -> no 

Why don't I get an error for that? What does def/else/end mean?

http://rubyfiddle.com/riddles/8df07

Answer 1

This is actually part of a larger syntactical structure:

def foo
  # method stuff
rescue
  # stuff if an exception is caught
else
  # stuff if no exception is caught
ensure
  # always run after rescue and else
end

But each section is optional! So you can leave out the rescue and ensure to get your example.