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POPython Object attribute search mechanism
 

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    <p>As per <a href="http://www.cafepy.com/article/python_attributes_and_methods/python_attributes_and_methods.html" rel="nofollow">this article</a></p> <blockquote> <p>When accessed objectname.attributename, the following objects are searched in sequence for the attribute:</p> </blockquote> <p>1. The object itself (<code>objectname.__dict__</code> or any Python-provided attribute of objectname).</p> <p>2. The object's type (<code>objectname.__class__.__dict__</code>). Observe that only <code>__dict__</code> is searched, which means only user-provided attributes of the class. In other words <code>objectname.__bases__</code> may not return anything even though <code>objectname.__class__.__bases__</code> does exist.</p> <p>3. The bases of the object's class, their bases, and so on. (<code>__dict__</code> of each of <code>objectname.__class__.__bases__</code>). More than one base does not confuse Python, and should not concern us at the moment. The point to note is that all bases are searched until an attribute is found.</p> <p>To test the theory I created this example</p> <pre><code>class Superb(object): svar=1 class Sub(Superb): ... class Leaf(Sub): def __init__(self): print(Leaf.svar) lobj=Leaf() </code></pre> <p>The instance creation worked and printed the value of Leaf.svar (as 1). This means that when resolving Leaf.svar, Python looked at the <em>base of the base of the Leaf object</em>, which is not something mentioned in the article. As per the article, <em>bases of the object's class</em> (i.e. type) are searched . I doubt that the article writer made any mistake it's most certainly a gap in my understanding. Can someone please clarify.</p>
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    1. USJoe Frambach
    1. USDev Maha
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    1. CO"The bases of the object's class, **their bases**, and so on"
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      1. USPavel Anossov
    2. COThe base of the object's (Leaf) class here is 'type' it's base is 'object' -> This path of search doesn't go thru Sub (Leaf's base) and Superb (Sub's base)
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      1. USDev Maha
    3. CONo, Leaf's `bases` are `(Sub,`). Try `print(Leaf.__bases__)`. How did you get `type`?
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      1. USPavel Anossov
 

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