我非常简单的自定义木偶类型和提供程序不工作

我正在阅读如何在Puppet中创建自定义类型和提供程序。
但我得到了错误:

Error: Could not autoload puppet/provider/createfile/ruby: undefined method `[]' for nil:NilClass

运行以下代码时:

mymodule/lib/puppet/type/filecreate.rb

require 'fileutils'

Puppet::Type.newtype(:filecreate) do
  ensurable do
    defaultvalues
    defaultto :present
  end

  @doc = "Create a file."

  newproperty(:name, :namevar => true) do
    desc "The name of the file"
  end

  newproperty(:path) do
    desc "The path of the file"
  end
end

mymodule/lib/puppet/provider/filecreate/rby.rb

require 'fileutils'

Puppet::Type.type(:filecreate).provide(:ruby) do
  desc "create file.."

  puts resource[:name]  # this line does not seem to work, why?
  puts resource[:path]  # this line does not seem to work, why?

  def create
    puts "create file..."
    puts resource[:name]
  end

 def destroy
    puts ("destroy file...")
    FileUtils.rm resource[:path]+resource[:name]
  end

  # Exit method never seems to be called
  def exists?
    puts "is method beeing called???"
    File.exists?(resource[:path])
  end
end

我猜获取参数值的方法, puts resource[:name] 不正确。那么我如何获取文件名 file.txt 声明为自定义类型的namevar filecreate (见下文)?

此外,方法 exists 似乎没有被调用。为什么?

还有我的初始化。pp包含以下简单代码:

class myclass {
  filecreate{'file.txt':
    ensure => present,
    path   => '/home/myuser/',
  }
}