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POWhat in the world is the attribute "__class__" in python
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  1. POWhat in the world is the attribute "__class__" in python
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    copied!<p>I have a question about <code>__class__</code> in python.</p> <p>The documentation says that <code>__class__</code> is the class to which a class instance belongs. So I conducted a series of experiments:</p> <pre><code>class counter: count = 0 def __init__(self): self.__class__.count += 1 NewCounter1 = counter() print NewCounter1.count #The result is 1 NewCounter2 = counter() print NewCounter2.count #The result is 2 print NewCounter2.__class__.count is NewCounter2.count #result: True </code></pre> <p>Everything goes well.</p> <p>Then I enter code as follows:</p> <pre><code>NewCounter2.__class__.count = 3 print NewCounter1.count #result:3 print NewCounter1.__class__.count #result:3 print NewCounter2.count #result:3 print NewCounter2.__class__.count #result:3 print NewCounter2.__class__.count is NewCounter2.count #result: True </code></pre> <p>From the code above, I thought that maybe <code>NewCounter1.count</code> equals <code>NewCounter1</code>, or <code>__class__.count</code>, but the following code surprised me:</p> <pre><code>NewCounter2.count = 5 print NewCounter1.count #result:3 print NewCounter1.__class__.count #result:3 print NewCounter2.count #result:5 print NewCounter2.__class__.count #result:3 print NewCounter2.__class__.count is NewCounter2.count #result: False </code></pre> <p>Why has <code>NewCounter2.count</code> changed but <code>NewCounter2.__class__.count</code> remained at 3? What's more, when I changed <code>NewCounter2.count</code>, <code>NewCounter2.__class__.count is NewCounter2.count</code> became <code>False</code>. What in the world is the attribute <code>__class__</code> ？</p>
 

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