Re: How to customize getattr(obj, prop) function ?
Try this: class Class: a='aa' b='bb' def __getattr__(self, ppt): return 'custom computed result' __getattr__ is only called when "normal" attribute lookup fails, so there's no need for the "hasattr" test. Also, I believe that __getattribute__ only applies to new-style classes (classes derived from "object"), and it will override *all* attribute accesses, anyway (meaning you'd have infinite recursion if you used it since you look up "self.ppt") Pierre wrote: > Hi, > > Sorry in advance, english is not my main language :/ > > I'd like to customize the result obtained by getattr on an object : if > the object has the requested property then return it BUT if the object > doesn't has actually this property return something else. > > In my case, I can't use getattr(object, property, default_value). > > I tried to write a class with a __getattr__ method and even a > __getattribute__ method but this doesn't do what I want > > Maybe I didn't correctly understand this : > http://docs.python.org/ref/attribute-access.html > > Here is a piece of my code : > = > class myclass: > """docstring""" > > a = 'aa' > b = 'bb' > > def __getattr___(self, ppt): > """getattr""" > if hasattr(self, ppt): > return self.ppt > else: > return "my custom computed result" > > def __getattribute__(self, ppt): > """getattribute""" > if hasattr(self, ppt): > return self.ppt > else: > return "my custom computed result" > > if __name__ == "__main__": > > d = myclass() > p1 = getattr(d, "a") > print p1 > p2 = getattr(d, "b") > print p2 > p3 = getattr(d, "c") > print p3 > > > I get an AttributeError when accessing to the property named "c". > > Any explanation/solution to my problem ? > -- http://mail.python.org/mailman/listinfo/python-list
Re: How to customize getattr(obj, prop) function ?
Try this: class Class: a='aa' b='bb' def __getattr__(self, ppt): return 'custom computed result' __getattr__ is only called when "normal" attribute lookup fails, so there's no need for the "hasattr" test. Also, I believe that __getattribute__ only applies to new-style classes (classes derived from "object"), and it will override *all* attribute accesses, anyway (meaning you'd have infinite recursion if you used it since you look up "self.ppt") Pierre wrote: > Hi, > > Sorry in advance, english is not my main language :/ > > I'd like to customize the result obtained by getattr on an object : if > the object has the requested property then return it BUT if the object > doesn't has actually this property return something else. > > In my case, I can't use getattr(object, property, default_value). > > I tried to write a class with a __getattr__ method and even a > __getattribute__ method but this doesn't do what I want > > Maybe I didn't correctly understand this : > http://docs.python.org/ref/attribute-access.html > > Here is a piece of my code : > = > class myclass: > """docstring""" > > a = 'aa' > b = 'bb' > > def __getattr___(self, ppt): > """getattr""" > if hasattr(self, ppt): > return self.ppt > else: > return "my custom computed result" > > def __getattribute__(self, ppt): > """getattribute""" > if hasattr(self, ppt): > return self.ppt > else: > return "my custom computed result" > > if __name__ == "__main__": > > d = myclass() > p1 = getattr(d, "a") > print p1 > p2 = getattr(d, "b") > print p2 > p3 = getattr(d, "c") > print p3 > > > I get an AttributeError when accessing to the property named "c". > > Any explanation/solution to my problem ? > -- http://mail.python.org/mailman/listinfo/python-list
Re: How to customize getattr(obj, prop) function ?
Try this: class Class: a='aa' b='bb' def __getattr__(self, ppt): return 'custom computed result' __getattr__ is only called when "normal" attribute lookup fails, so there's no need for the "hasattr" test. Also, I believe that __getattribute__ only applies to new-style classes (classes derived from "object"), and it will override *all* attribute accesses, anyway (meaning you'd have infinite recursion if you used it since you look up "self.ppt") Pierre wrote: > Hi, > > Sorry in advance, english is not my main language :/ > > I'd like to customize the result obtained by getattr on an object : if > the object has the requested property then return it BUT if the object > doesn't has actually this property return something else. > > In my case, I can't use getattr(object, property, default_value). > > I tried to write a class with a __getattr__ method and even a > __getattribute__ method but this doesn't do what I want > > Maybe I didn't correctly understand this : > http://docs.python.org/ref/attribute-access.html > > Here is a piece of my code : > = > class myclass: > """docstring""" > > a = 'aa' > b = 'bb' > > def __getattr___(self, ppt): > """getattr""" > if hasattr(self, ppt): > return self.ppt > else: > return "my custom computed result" > > def __getattribute__(self, ppt): > """getattribute""" > if hasattr(self, ppt): > return self.ppt > else: > return "my custom computed result" > > if __name__ == "__main__": > > d = myclass() > p1 = getattr(d, "a") > print p1 > p2 = getattr(d, "b") > print p2 > p3 = getattr(d, "c") > print p3 > > > I get an AttributeError when accessing to the property named "c". > > Any explanation/solution to my problem ? > -- http://mail.python.org/mailman/listinfo/python-list
Re: How to customize getattr(obj, prop) function ?
I tested the exact code I sent you on python 2.4.1. What version of Python are you using? Thanks, Rick Pierre wrote: > Nop I get the same AttributeError when I try to access to the property > "c"... > -- http://mail.python.org/mailman/listinfo/python-list
Re: How to customize getattr(obj, prop) function ?
I tested the exact code I sent you on python 2.4.1. What version of Python are you using? Thanks, Rick Pierre wrote: > Nop I get the same AttributeError when I try to access to the property > "c"... > -- http://mail.python.org/mailman/listinfo/python-list
