Subclass str: where is the problem?

[pascal . parent]

Hello, can anybody explain/help me:

Python 2.4.2 (#2, Sep 30 2005, 21:19:01)
[GCC 4.0.2 20050808 (prerelease) (Ubuntu 4.0.1-4ubuntu8)] on linux2


class Upper(str):
  def __new__(cls, value):
return str.__new__(cls, value.upper())

u = Upper('test')
u
'TEST'
type(u)

u = Upper('')
u
''
type(u)



All seems to be ok...

class MyObject(object):
  def __init__(self, dictionary = {}):
self.id = dictionary.get('id', '')
  def __setattr__(self, attribute, value):
value = type(value) is type('') and Upper(value) or value
object.__setattr__(self, attribute, value)

m = MyObject({'id': 'test'})
m.id
'TEST'
type(m.id)

m = MyObject()
m.id
''
type(m.id)


Why is m.id a str ?
Thanks.

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Re: Subclass str: where is the problem?

[pascal . parent]

This is good... try this:

value = 'test'
value
'test'
type(value)

value = type(value) is type('') and Upper(value) or value
value
'TEST'
type(value)
 

value = 1
value
1
type(value)

value = type(value) is type('') and Upper(value) or value
value
1
type(value)


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Re: Subclass str: where is the problem?

[pascal . parent]

Effectively.
Thanks a lot Peter and Harold.

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__getattribute__ and __slots__

[pascal . parent]

Hi,
I try to define a (new-style) class who:
- have a __slots__ defined to be strict attributes,
- return None if the attribute is 'ok' but not set, or raise a 'normal'
error if the attribute isn't in __slots__.

This code runs, but is it the good way?

Thanks.

class test(object):
 __slots__ = ['id']
 def __getattr__(self, attr):
 if not attr in self.__slots__: raise AttributeError
 try:
 return self.attr
 except:
 return None

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