module_syntax.rb

def f a, b = Proc.new
  Module.new {
    const_set :M__, self
    module_exec self, *a, &b
  }
end

m1 = module f(:m1_ok) { |mod, sym| @foo = sym }::M__
  def foo
    @foo
  end
  extend self
  self
end

p m1.foo #=> :m1_ok

m2 = module f(:m2_ok, -> mod, sym {
  extend m1
  @bar = sym
})::M__
  @foo = :m2_foo
  BAR = @bar
  self
end

p m2.foo #=> :m2_foo
p m2::BAR #=> :m2_ok

m3 = module f(:m3_ok) do |mod, sym|
  extend m1
  self::FOO = sym
end::M__
  @foo = [FOO, Module.nesting]
  self
end

p m3.foo #=> [:m3_ok, [#<Module:0x41398b90>]]