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copied!<p>How about only calling the decorated method if it has been validated? You can pass the return value of the <code>validate</code> method along if you like:</p> <pre><code>class BaseClass(object): def getvalue(self): return True def validate(input_function): def wrapper(self, *args, **kwargs): self.validated = self.getvalue() if not self.validated: print "Not validated." return input_function(self, validated=self.validated, *args, **kwargs) return wrapper validate = staticmethod(validate) class ExtendedClass1(BaseClass): @BaseClass.validate def do_some_work(self, validated=None): print "Things are validated if the method got this far.", validated class ExtendedClass2(BaseClass): @BaseClass.validate def do_some_work(self, validated=None): print "Things are validated if the method got this far.", validated class ExtendedClass3(BaseClass): def do_some_work(self): print "This one doesn't require validation." work1 = ExtendedClass1() work1.do_some_work() work2 = ExtendedClass2() work2.do_some_work() work3 = ExtendedClass3() work3.do_some_work() </code></pre> <p>The key here is adding <code>self</code> to the <code>wrapper</code> function. What happens is that your decorated functions do not get bound to the instance (and become methods), but the function returned by the decorator (<code>wrapper</code> in the above example) get's bound instead. So this function will get the <code>self</code> (the instance) parameter passed in when called! It's important to remember that what a <code>@decorator</code> does is simply call <code>decorator</code> passing in the function you are decorating, and then <em>replace</em> the function you are decorating with whatever the decorator returned. In your example this is <code>wrapper</code>, and to the class, there is no difference between that and the original function before decorating.</p> <p>In the above example, I declared <code>self</code> explicitly. If we hadn't, we could also have just taken it from <code>args</code>:</p> <pre><code>def validate(input_function): def wrapper(*args, **kwargs): print "args[0] is now the instance (conventionally called 'self')", args[0] self = args[0] self.validated = self.getvalue() if not self.validated: print "Not validated." return input_function(validated=self.validated, *args, **kwargs) </code></pre> <p>Also note that we pass an extra keyword argument to the wrapped method, named <code>validated</code>. This is entirely optional, you can just drop the <code>validated=self.validated</code> and <code>validated=None</code> parts from the example. </p>

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