擅长:python、mysql、java
<p>来自Python 2<a href="http://docs.python.org/reference/expressions.html#parenthesized-forms" rel="noreferrer">docs</a>和Python 3<a href="http://docs.python.org/release/3.1.3/reference/expressions.html#parenthesized-forms" rel="noreferrer">docs</a>:</p>
<blockquote>
<p>... two occurrences of the empty tuple may or may not yield the same object.</p>
</blockquote>
<p>换句话说,您不能指望<code>() is ()</code>来计算为true。在</p>