擅长:python、mysql、java
<p>不需要在<code>subtraction</code>或<code>addition</code>中指定<code>x</code>和<code>y</code>:</p>
<pre><code>class calculator:
def __init__(self, x, y):
self.x = x
self.y = y
def addition(self):
return self.x + self.y
def subtraction(self):
if self.x > self.y:
return self.y - self.x
else:
return self.x - self.y
</code></pre>
<p><code>self</code>将涵盖为您检索<code>x</code>和<code>y</code>,因为您正在引用这些实例变量。否则,需要在调用时指定它们:</p>
<pre><code># Yields 2-1 rather than 4-3
result = calculator(1,2).subtraction(3,4)
</code></pre>
<p>但是,在实例化类时需要指定它们</p>
<pre><code>myinst = calculator(1,2)
</code></pre>