Newbie: Why doesn't this work

[Jeff McNeil]

Perhaps you'd be better off using a standard property?  Within your Person
class, you can define a property 'name' to handle what you're trying to do:
Python 2.5 (r25:51918, Sep 19 2006, 08:49:13)
[GCC 4.0.1 (Apple Computer, Inc. build 5341)] on darwin
Type "copyright", "credits" or "license()" for more information.

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IDLE 1.2
>>>

>>> class Person(object):
def __init__(self, fname, lname):
self.fname = fname
self.lname = lname
def get_name(self):
return '%s %s' % (self.fname, self.lname)
def set_name(self, name):
self.fname, self.lname = name
name = property(get_name, set_name)

>>> p = Person('first', 'last')
>>> p.name
'first last'
>>> p.name = ('first2', 'last2')
>>> p.name
'first2 last2'
>>>


I found http://users.rcn.com/python/download/Descriptor.htm#properties to be
a pretty good reference.

Thanks,

Jeff


On 12/31/07, ct60 at aol.com <ct60 at aol.com> wrote:
>
> Hi Python Community:
>
> Despite my new-ness to Python  I have alreadhy been able to do some (I
> think) amazing things.  It is a truly elegant and smart language.
>
> Yet, I can not seem to get a handle on something simple.
>
> I would like to make a class which has private varaiables fName and
> lName.  It should have a property "name" which can get or set a name.
> Something like as follows:
>
> class Person:
>     def __init__(self, fName="", lName=""):
>         self.__fName = fName
>         self.__lName = lName
>
>     def __getattr__(self, attr):
>         if attr == "name":
>             return self.__fName + " " + self.__lName
>
>     def __setattr__(self, attr, value):
>         # this assumes that value is a tuple of first and last name
>         if attr == "name":
>             self.__fName, self.__lName = value
>
>
> P = Person()
>
> P.name = ("Joe", "Smith")
>
> print P.name
>
> This fails with the following note:
>
> >>>
> Traceback (most recent call last):
>   File "C:\Python\testObject.py", line 20, in <module>
>     print P.name
>   File "C:\Python\testObject.py", line 8, in __getattr__
>     return self.__fName + " " + self.__lName
> TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'
>
> I don't understand why this fails.  I thought perhaps I need to make
> the __getattr__ function like this
>
>     def __getattr__(self, attr):
>         if attr == "name":
>             return self.__fName + " " + self.__lName
>         elif attr == "__fName":
>             return self.__fName
>         elif attr == "__lName":
>             return self.__lName
>
> But that still fails.
>
> Can someone please tell me what I am doing wrong?
>
> Thansk in advance,
>
> Chris (ct60 at aol.com)
> --
> http://mail.python.org/mailman/listinfo/python-list
>
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