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    <p>There is no "casting" in Python. Any subclass of a class is considered an instance of its parents. Desired behavior can be achieved by proper calling the superclass methods, and by overriding class attributes.</p> <p>What you can do on your example, is to have to have a subclass initializer that receives the superclass and copies its relevant attributes - so, your MutantReturnstatement could be written thus:</p> <pre><code>class MutantReturnStatement(ReturnStatement): def __init__(self, previous_object=None): if previous_object: self.attribute = previous_object.attribute # repeat for relevant attributes def act(self): print "I'm wrapping ReturnStatement." return ReturnStatement().act() </code></pre> <p>And then change your MutantWorking class to:</p> <pre><code>class MutantWorking(Working): def do(self): print "I am wrapping Working." return MutantReturnStatement(Working().do()) </code></pre> <p>There are Pythonic ways for not having a lot of <code>self.attr = other.attr</code> lines on the <code>__init__</code>method if there are lots (like, more than 3 :-) ) attributes you want to copy - the laziest of which wiuld be simply to copy the other instance's <code>__dict__</code> attribute. </p> <p>Alternatively, <strong>if you know what you are doing</strong>, you could also simply change the <code>__class__</code> attribute of your target object to the desired class - but that can be misleading and carry you to subtle errors (the <code>__init__</code> method of the subclass would not be called, would not work on non-python defined classes, and other possible problems), I don't recomment this approach - this is not "casting", it is use of introspection to bruteforce an object change and is only included for keeping the answer complete:</p> <pre><code>class MutantWorking(Working): def do(self): print "I am wrapping Working." result = Working.do(self) result.__class__ = MutantReturnStatement return result </code></pre> <p>Again - this should work, but don't do it - use the former method.</p> <p>By the way, I am not too experienced with other OO languages, that allow casting - but is casting to a subclass even allowed in any language? Does it make sense? I think casting s only allowed to parentclasses.</p>
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    1. POHow to cast object in Python
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    1. USjsbueno
    1. USjsbueno
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    1. COCould you please post the answer in code? Otherwise I don't think you answered my question.
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      1. USVisko
    2. CO@jsbueno, yes you *can* define a cast from any object to any object in for example C++.
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      1. USJohan Lundberg
    3. COI don't necessarily know the non-mutant classes' attributes. Let's say they are C++ libraries imported to Python.
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