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POHow to create objects dynamically in an elegant way in python?
 

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  1. POHow to create objects dynamically in an elegant way in python?
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    <p>I have two classes that I would like to merge into a composite. These two classes will continue to be used standalone and I don't want to modify them. For some reasons, I want to let my composite class creating the objects. I am thinking about something like the code below (it is just an example) but I think it is complex and I don't like it very much. I guess that it could be improved by some techniques and tricks that I ignore.</p> <p>Please note that the composite is designed to manage a lot of different classes with different constructor signatures.</p> <p>What would recommend in order to improve this code?</p> <pre><code>class Parent: def __init__(self, x): self.x = x class A(Parent): def __init__(self, x, a="a", b="b", c="c"): Parent.__init__(self, x) self.a, self.b, self.c = a, b, c def do(self): print self.x, self.a, self.b, self.c class D(Parent): def __init__(self, x, d): Parent.__init__(self, x) self.d = d def do(self): print self.x, self.d class Composite(Parent): def __init__(self, x, list_of_classes, list_of_args): Parent.__init__(self, x) self._objs = [] for i in xrange(len(list_of_classes)): self._objs.append(self._make_object(list_of_classes[i], list_of_args[i])) def _make_object(self, the_class, the_args): if the_class is A: a = the_args[0] if len(the_args)&gt;0 else "a" b = the_args[1] if len(the_args)&gt;1 else "b" c = the_args[2] if len(the_args)&gt;2 else "c" return the_class(self.x, a, b, c) if the_class is D: return the_class(self.x, the_args[0]) def do(self): for o in self._objs: o.do() compo = Composite("x", [A, D, A], [(), ("hello",), ("A", "B", "C")]) compo.do() </code></pre>
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    1. COAre you talkning about Meta Classes? http://www.ibm.com/developerworks/linux/library/l-pymeta.html
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    2. CO*Metaclasses are deeper magic than 99% of users should ever worry about. If you wonder whether you need them, you don't (the people who actually need them know with certainty that they need them, and don't need an explanation about why)*. -- Tim Peters
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    3. COI don't know if metaclass can be a solution of this problem. I am not very familiar with this concept. I will look at the link you gave carefully. Thanks
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