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copied!<p>You can change the metaclass after class creation the same way that you can change the class of an object, however you'd have a lot of issues. For starters, the initial metaclass needs to be different from <code>type</code>, the <code>__init__</code> and <code>__new__</code> of the new metaclass won't be called (though you can manually call <code>__init__</code> or a method that performs <code>__init__</code>'s job).</p> <p>Possibly the least troublesome way to change the metaclass is to recreate the class again from scratch:</p> <pre><code>B = MetaClass(B.__name__, B.__bases__, B.__dict__) </code></pre> <p>But if you insist on changing the metaclass dynamically, you first need to define B with a temporary custom metaclass:</p> <pre><code>class _TempMetaclass(type): pass class B: __metaclass__ = _TempMetaclass # or: type('temp', (type, ), {}) </code></pre> <p>Then you can define the metaclass like that:</p> <pre><code>class MetaClass(type): def __init__(cls, *a, **kw): super(MetaClass, cls).__init__(*a, **kw) cls._actual_init(*a, **kw) def _actual_init(cls, *a, **kw): # actual initialization goes here </code></pre> <p>And then do something like:</p> <pre><code>B.__class__ = MetaClass MetaClass._actual_init(B, B.__name__, B.__bases__, B.__dict__) </code></pre> <p>You also need to make sure that all the initialization of the class is done <code>_actual_init</code>. You can also add a <code>classmethod</code> to the metaclass that changes the metaclass for you.</p> <p>Both solutions have the slight shortcoming that B's bases would be limited - they need to be compatible with both the original and the new metaclass, but I guess that's not an issue in your case.</p>

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