module Sprockets::Utils

def module_include(base, mod)
  MODULE_INCLUDE_MUTEX.synchronize do
    old_methods = {}
    mod.instance_methods.each do |sym|
      old_methods[sym] = base.instance_method(sym) if base.method_defined?(sym)
    end
    mod.instance_methods.each do |sym|
      method = mod.instance_method(sym)
      if base.method_defined?(sym)
        base.send(:alias_method, sym, sym)
      end
      base.send(:define_method, sym, method)
    end
    yield
  ensure
    mod.instance_methods.each do |sym|
      base.send(:undef_method, sym) if base.method_defined?(sym)
    end
    old_methods.each do |sym, method|
      base.send(:define_method, sym, method)
    end
  end
end