Ethan Furman wrote:
Greetings List!
I'm writing a wrapper to the datetime.date module to support having no
date. Its intended use is to hold a date value from a dbf file, which
can be empty.
The class is functional at this point, but there is one thing I would
like to change -- datetime.date.max and datetime.date.min are class
attributes of datetime.date, and hold datetime.date values. At this
point I have to have two lines outside the actual class definition to do
the same thing, e.g.:
<trimmed down class code>
class NullDate(object):
"adds null capable DateTime.Date constructs"
__slots__ = ['_date']
def __new__(cls, date='', month=0, day=0):
nulldate = object.__new__(cls)
nulldate._date = ""
.
.
.
return nulldate
def __getattr__(self, name):
if self:
attribute = self._date.__getattribute__(name)
return attribute
else:
if callable(dt.date.__dict__[name]):
return int
else:
return 0
def __nonzero__(self):
if self._date:
return True
return False
@classmethod
def fromordinal(cls, number):
if number:
return cls(dt.date.fromordinal(number))
else:
return cls()
NullDate.max = NullDate(dt.date.max)
NullDate.min = NullDate(dt.date.min)
</trimmed down class code>
How can I move those last two lines into the class definition so that:
1) they are class attributes (not instance), and
2) they are NullDate type objects?
~ethan~
I resisted posting a similar question recently. After much
consideration, I realized that the inability to reference a class inside
its own definition must have been a deliberate design of the language.
So the short answer is you can't.
The way you have done it is best--its not a hack and is good style.
James
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