Hrvoje Niksic wrote:
> import os
> from gtk import *
>
> class Foo (GtkWindow):
> home = os.environ["HOME"]
>
> def __init__ (self):
> GtkWindow.__init__ (self)
>
> def changehome (self, newhome):
> self.home = newhome
>
> foo = Foo ()
> print foo.home
> foo.changehome ("/")
> print foo.home
Ok, the problem here is that when we assign to self.home, our
__setattr__ function sets home as a shared attribute, since 'home'
doesn't exist in the instance dictionary. However, the instance's
__getattr__ method is *NEVER* called, so we don't get a chance to return
the "updated" value.
class Bar:
home = os.environ["HOME"]
def __init__(self):
pass
def changehome(self,newhome):
self.home = newhome
def __getattr__(self,attr):
print "__getattr__: %s" % attr
return self.__dict__[attr]
def __setattr__(self,attr,value):
print "__setattr__: %s, %s" % (attr,str(value))
self.__dict__[attr] = value
bar1,bar2 = Bar(),Bar()
print bar1.home,bar2.home
bar1.changehome ("/tmp")
print bar1.home,bar2.home
When you run the above, you get the following output (or something
similar!):
/root /root
__setattr__: home, /tmp
/tmp /root
Significant things to notice are that assigning to home creates an
instance attribute, so that the change isn't reflected in bar2. Also,
notice that __getattr__ is *NEVER* called.
I think we can finally finish this by assigning to the shared attribute
if '_o' is defined, but *ALWAYS* setting the non-shared attribute. With
this technique, __getattr__ should only be called from signal handlers,
where the instance won't contain the attribute, so we need to fetch it
from the shared dictionary.
I'll post a patch to test this shortly (I want to get the current
snapshot first).
--
Richard Fish Enhanced Software Technologies, Inc.
Software Developer 4014 E Broadway Rd Suite 405
[EMAIL PROTECTED] Phoenix, AZ 85040
(602) 470-1115 http://www.estinc.com
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