devanl devanl - 4 months ago 8
Python Question

python object member variable missing

I have a constructor which creates a member object of a sub-class:

class OpenSprinkler:
class CV:
my_args = ['rsn', 'rbt', 'en', 'rd', 're']
my_longhand = {'reset_all':'rsn',
'reboot':'rbt',
'enable':'en',
'rain_delay':'rd',
'remote_extension':'re'}

def __init__(self, p):
print('set parent of %r\n' % (self,))
self.parent = p
print('parent set to %r\n' % (p,))
self.my_args.extend(self.my_longhand.keys())

def __init__(self, hostname, password, log=None):
self.cv = self.CV(self)


the output confirm that the constructor for the member was called:

>>> c = openSprinkler.OpenSprinkler('foo','bar')
set parent of <openSprinkler.OpenSprinkler.CV object at 0xb6a58df0>

parent set to <openSprinkler.OpenSprinkler object at 0xb6a58dd0>

>>> repr(c.cv)
'<openSprinkler.OpenSprinkler.CV object at 0xb6a58df0>'


but when I look at the members,
cv.parent
does not appear to exist:

>>> dir(c.cv)
['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'my_args', 'my_longhand']


cv.my_args
contains the extended list. Any idea what's going on here?

UPDATE:
As Alec pointed out, the code example actually does work.
The actual problem had been omitted from the example and was that I had chosen to override the setattr method without allowing parent to be set.

originally:

def __setattr__(self, name, value):
if name in self.my_args:
if name in self.my_longhand.keys():
name = self.my_longhand[name]
self.parent._json_get('cv', {name:value})


now:

def __setattr__(self, name, value):
if name in self.my_args:
if name in self.my_longhand.keys():
name = self.my_longhand[name]
self.parent._json_get('cv', {name:value})
else:
super().__setattr__(name, value)

Answer

Is it possible that you have an openSprinkler object somewhere else in the code that's being called? Instantiating OpenSprinkler directly seems to contain your methods:

c = OpenSprinkler('foo','bar')

print(dir(c.cv))
# ['__class__', '__delattr__', '__dict__', '__dir__', 
# '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', 
# '__gt__', '__hash__', '__init__', '__le__', '__lt__', 
# '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', 
# '__repr__', '__setattr__', '__sizeof__', '__str__', 
# '__subclasshook__', '__weakref__', 'my_args', 'my_longhand', 'parent']