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POCreate a subclass, instead, when calling the creation of a class, depending on some logic
 

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    <p><em>The question that I posted initially was lacking so here is an explanation that I hope will satisfy everyone and cancel some down votes that I received on it.</em></p> <p>I would like to have an intelligence inside a class, that with the creation of an instance, it is decided that the instance would be of a different class, which is one of the subclasses of this class, according to some logic.</p> <p>More specifically, I am making a <a href="https://en.wikipedia.org/wiki/Magic_square" rel="nofollow">Magic Square</a> solver as a learning exercise and:</p> <ul> <li>I want to have a <code>MagicSquare</code> class that will contain the logic of a MagicSquare.</li> <li>I want to have <code>OddMagicSquare</code> and <code>EvenMagicSquare</code> subclasses of that class that will contain the logics of solving these two types of Magic Squares.</li> <li>I want to be able to call the creation of a <code>MagicSquare</code>, providing it's size, <code>n</code>, and have the intelligence within <code>MagicSquare</code> determine which subclass to create an instance of, instead of the generic, top, class <code>MagicSquare</code>.</li> </ul> <p>I understand that the intelligence to determine which subclass (<code>OddMagicSquare</code>/<code>EvenMagicSquare</code>) to create an instance of <em>can be</em> (and perhaps would be easier to implement if it would be) <strong>outside</strong> of <code>MagicSquare</code>. The reason that I want it to be inside <code>MagicSquare</code> is perhaps a gut feeling. I have a hunch that it would be more clean and tidy this way because the logic of determining which kind of Magic Square a certain Magic Square is, seems to me, to belong in the <code>MagicSquare</code> class.</p>
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    1. COThis smells like an [XY problem](http://meta.stackexchange.com/questions/66377/what-is-the-xy-problem). Why do you want to re-class it? Why not use a "factory function" (or, equivalently, a `@classmethod` as an alternate constructor) that constructs an object of the right class in the first place? Or a `__new__` method? Why wait until you've gotten to `__init__` and then change the class?
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    2. CO@abarnert I don't specifically want to re-class. I want the code that determines which subclass the object will be an instance of to be in the top, `Car`, class. Is there a reason for it not to be in `__init__`? Would it be better in `__new__`?
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    3. COYes, there is a reason for it not to be in `__init__`. Because by the time you've gotten into the base's `__init__`, it's obviously too late to just construct the object normally because you're already in the middle of object construction. `__new__` would probably be better than `__init__`, but an alternate constructor `@classmethod` (or some other variation on the theme—a factory, a Cocoa-style "class cluster" constructor, …) would probably be even _better_.
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