擅长:python、mysql、java
<blockquote>
<p>i've got a metaclass that reads this information and does some setup</p>
</blockquote>
<p>大多数使用元类的框架都提供了解决这个问题的方法。例如,<a href="http://docs.djangoproject.com/en/1.0/ref/models/fields/#foreignkey" rel="noreferrer">Django</a>:</p>
<pre><code>subplan = ForeignKey('self')
</code></pre>
<p><a href="http://code.google.com/appengine/docs/python/datastore/typesandpropertyclasses.html#SelfReferenceProperty" rel="noreferrer">Google App Engine</a>:</p>
<pre><code>subplan = SelfReferenceProperty()
</code></pre>
<p>解决方案的问题是,大多数ORM元类都希望在创建类时存在类属性,比如在以后附加属性或使用<code>__new__</code>。</p>