Why does __init__ not get called?

[Rob Conner]

I'm still working on my DateTime class from last week...
Why does __init__ not get called?

The docs at
http://www.python.org/dev/doc/devel/...omization.html
read "If __new__() returns an instance of cls, then the new instance's
__init__() method will be invoked" and as far as I can tell cls is very
much an instance of DateTime

************
import datetime
_datetime = datetime.dateti me

class DateTime(_datet ime):
"""
Identical to builtin datetime.dateti me, except it accepts
invalid dates and times as input.
"""
_valid = True
__dict__ = _datetime.__dic t__

def __init__(self, year, month, day, *args, **kw):
print "init called"
_valid = False
self.year = year
self.month = month
self.day = day
self.args = args
self.kw = kw

def throwError():
raise ValueError, 'Invalid Date'
for method in _datetime.__dic t__.keys():
if method!='__doc_ _':
setattr(self, method, throwError)
def __new__(cls, year, month, day, *args, **kw):
print "new called"
try:
return _datetime.__new __(cls, year, month, day, *args,
**kw)
except ValueError:
return cls
*************

[Steven Bethard]

Steven Bethard wrote:

def __call__(cls, *args, **kwargs):
obj = cls.__new__()
if not isinstance(obj. __class__, cls): ^^^^^^^^^^
issubclass
return obj
obj.__class__._ _init__(obj, *args, **kwargs)
return obj

STeVe

[Fuzzyman]

If you subclass strings you have to do your magic in __new__ rather
than __init__. It receives the same arguments as you would normally
expect to go to __init__.

(Except cls rather than self).

Best Regards,

Fuzzy
http://www.voidspace.org.uk/python