擅长:python、mysql、java
<p>你的代码没有正确缩进。把它改成这个,它就会起作用(可能不是预期的那样,但它会起作用):</p>
<pre><code>for user in userLinks:
url = userLinks[user]
response = urllib2.urlopen(url)
html = response.read()
if userSources[user] != html:
del userSources[user]
del userLinks[user]
api.PostDirectMessage(user,'It appears the page has updated! Your item may be back in stock!')
</code></pre>
<p>发生此错误是因为您在<code>for</code>循环中定义了<code>response</code>,但是如果循环没有运行(即<code>userLinks == []</code>),则永远不会设置该变量。在</p>