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    <p>Python doesn't have (or need) "parameterized classes", so it's hard to provide examples of them in Python;-). A metaclass is simply "the class of a class": normally <code>type</code> (as long, in Py2, as you remember to make the class new-style by inheriting from <code>object</code>, or some other built-in type or other new-style class -- old-style classes are a legacy artefact in Py2, fortunately disappeared in Py3, and you should ideally just forget about them). You can make a custom metaclass (usually subclassing <code>type</code>) for several advanced purposes, but it's unlikely that you'll ever <em>need</em> to (esp. considering that, since python 2.6, much of what used to require a custom metaclass can now be done more simply with a class decorator).</p> <p>Given any class C, <code>type(C)</code> is its metaclass.</p> <p>A parameterized class is a completely different concept. Closest you can come to it in Python is probably a factory function that makes and returns a class based on its arguments:</p> <pre><code>def silly(n): class Silly(object): buh = ' '.join(n * ['hello']) return Silly Silly1 = silly(1) Silly2 = silly(2) a = Silly1() print(a.buh) b = Silly2() print(b.buh) </code></pre> <p>will print</p> <pre><code>hello hello hello </code></pre> <p>Again, it's definitely <strong>not</strong> something you'll need often — making several classes that differ just by one or a few arguments. Anyway, as you can see, it has absolutely nothing to do with the classes' class (AKA metaclass), which is always <code>type</code> in this example (and in almost every more realistic example I could think of — I just chose to give a simple example, where the point of doing this is hard to discern, rather than a realistic and therefore necessarily very complex one ;-).</p>
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    1. POWhat is the difference between a parameterized class and a metaclass (code examples in Python please)?
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    1. USAlex Martelli
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    1. COI switched to Py3 a couple of days ago, thinking that since I'm just a student right now, I should learn the 'hip new thing' of tomorrow. Guess that was a smart move :-)
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      1. USyrsnkd
    2. CO+1. Good explanation.
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      1. USManoj Govindan
    3. CO+1 Excellent explanation as always.
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      1. USKatriel
 

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