擅长:python、mysql、java
<p>任何类方法中的第一个变量都是对类实例的引用。您的方法需要两个变量:<code>val1</code>和<code>val2</code>,但是当您调用<code>self.near(val1, val2)</code>时,它相当于调用一个以<code>self</code>、<code>val1</code>和{<cd2>}作为参数的函数。在</p>
<p>从<a href="https://docs.python.org/2/tutorial/classes.html" rel="nofollow">Python Docs on Classes</a>,第二段:</p>
<blockquote>
<p>the method function is declared with an explicit first argument
representing the object, which is provided implicitly by the call</p>
</blockquote>