On Thu, 4 Sep 2008 12:06:14 +0200, Marco Bizzarri wrote:
>> As far as I understand you, you need descriptors:
>> http://users.rcn.com/python/download/Descriptor.htm
> I know descriptors a litte, Wojtek, but didn't use them often; can you
> elaborate a little more on your idea?
Marco, I think that I misunderstood the OP, but I was thinking
about immutable (or set-once) attributes. Something like this:
---
class SetOnce(object):
def __init__(self):
self._attr1 = ""
self._attr1flag = False
def setatt(self, x):
if self._attr1flag:
raise ValueError("attribute already set")
self._attr1flag = True
self._attr1 = x
def getatt(self):
return self._attr1
attr1 = property(getatt, setatt)
a = SetOnce()
a.attr1 = 1
print a.attr1
try:
a.attr1 = 2
except ValueError:
print a.attr1
---
$ python immutattr.py
1
1
$
--
Regards,
Wojtek Walczak,
http://tosh.pl/gminick/
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