Module.prepend vs. alias_method_chain: FIGHT!

code.rb

# classic situation:

class B1
  def foo
    'B'
  end
end

module A1
  def foo
    'A' + super
  end
end
B1.prepend A1

class B1
  def foo_with_c
    'C' + foo_without_c
  end
  alias_method_chain :foo, :c
end

# but this doesn't work!!!
# [13] dev (main)> B1.new.foo
# SystemStackError: stack level too deep

# This works:

class B2
  def foo
    'B'
  end
end

class B2
  def foo_with_c
    'C' + foo_without_c
  end
  alias_method_chain :foo, :c
end

module A2
  def foo
    'A' + super
  end
end
B2.prepend A2

# [19] dev (main)> B2.new.foo
# => "ACB"
# but it's really scary!

# Module#prepend is definitely the new hotness, and much better then
# alias_method_chain, but you need to be careful about using it in a
# legacy codebase, or else you can run into all sorts of issues.