python对象构造函数没有被调用？

Question

I am using python 2.7.3 I have a couple of classes:

class GpioSettings:

class GpioSettings(object):
  __initialized__ = False
  PIR_PIN = 6
  GPIO = None
  RISING = None
  FALLING = None
  IN = None

  def __init__(self):
    print "starting to initialize gpio settings"
    if GpioSettings.__initialized__:
      print "gpio settings already initialized now"
      return
    else:
      print "initializing gpio settings now"
      GpioSettings.__initialized__ = True
      try:
        import RPi.GPIO as GPIO
        GpioSettings.GPIO = GPIO
        GpioSettings.RISING = GPIO.RISING
        GpioSettings.FALLING = GPIO.FALLING
        GpioSettings.IN = GPIO.IN
        GPIO.setmode(GPIO.BCM)
        GpioSettings.__piFunctionsLoaded__ = True
      except:
        GpioSettings.__piFunctionsLoaded__ = False

  @staticmethod
  def piFunctionsLoaded():
    return GpioSettings.__piFunctionsLoaded__

  @staticmethod
  def gpio():
    return GpioSettings.GPIO

class Pir:

import os
import sys
import time
sys.path.append(os.path.abspath("/home/pi/garageMonitor/django/lib"))
from gpioSettings import GpioSettings
from osUtils import checkUser

class Pir(object):
  def __init__(self, callback):
    self.gpio = GpioSettings()
    if not self.gpio.piFunctionsLoaded():
      return
    self.gpio.gpio().setup(self.gpio.PIR_PIN, gpio.IN)
    self.gpio.gpio().add_event_detect(self.gpio.PIR_PIN, gpio.RISING, callback=callback, bouncetime=300)

def testCallback(channel):
  print "Motion Detected on " + str(channel)

if __name__ == "__main__":
  checkUser()
  gpio = GpioSettings()
  if gpio.piFunctionsLoaded():
    print "loaded"
    pir = Pir(testCallback)
    time.sleep(30)
  else:
    print "not loaded"

and python file startPio.py:

import os
import sys
sys.path.append(os.path.abspath("/home/pi/garageMonitor/django/lib"))
from gpioSettings import GpioSettings
from osUtils import checkUser
from piPir import Pir

def pirCallback(channel):
  print "Motion Detected on " + str(channel)

if __name__ == "__main__":
  checkUser()
  print "initializing gpio now"
  gpio = GpioSettings()
  if gpio.piFunctionsLoaded():
    print "loaded here"
    pir = Pir(pirCallback)
  else:
    print "not loaded"

I am trying to make a singleton of the GpioSettings class so that I can use it in multiple classes. It may not be running on the appropriate hardware (and RPi.GPIO may not be available) so I am trying to shield this from the other classes.

If I run: sudo python ./piPir.py it works fine (GpioSettings is called) and I get the expected output:

starting to initialize gpio settings
initializing gpio settings now
gpio settings already initialized now
loaded
starging to initialize gpio settings
gpio settings already initialized now
Motion Detected on 6

If I run: sudo python ./startPio.py (both GpioSettings and piPir are called) I get the following:

sudo python ./startPio.py            
initializing gpio now
loaded here
Traceback (most recent call last):
  File "./startPio.py", line 17, in <module>
    pir = Pir(pirCallback)
  File "/home/pi/garageMonitor/django/lib/piPir.py", line 13, in __init__
    self.gpio.gpio().setup(self.gpio.PIR_PIN, gpio.IN)
AttributeError: GpioSettings instance has no attribute 'gpio'

What's killing me is that "starting to initialize gpio settings" does not get printed when "gpio = GpioSettings()" is called from startPio.py!

Obviously I am tired and need some rest as I am sure it is obvious.

So I put everything into one file to make debugging a little easier:

class GpioSettings(object):
  __initialized__ = False
  PIR_PIN = 6
  GPIO = None
  RISING = None
  FALLING = None
  IN = None

  def __init__(self):
    print "starting to initialize gpio settings"
    if GpioSettings.__initialized__:
      print "gpio settings already initialized now"
      return
    else:
      print "initializing gpio settings now"
      GpioSettings.__initialized__ = True
      try:
        import RPi.GPIO as GPIO
        GpioSettings.GPIO = GPIO
        GpioSettings.RISING = GPIO.RISING
        GpioSettings.FALLING = GPIO.FALLING
        GpioSettings.IN = GPIO.IN
        GPIO.setmode(GPIO.BCM)
        GpioSettings.__piFunctionsLoaded__ = True
      except:
        GpioSettings.__piFunctionsLoaded__ = False

  @staticmethod
  def piFunctionsLoaded():
    return GpioSettings.__piFunctionsLoaded__

  @staticmethod
  def gpio():
    return GpioSettings.GPIO


##############################################################################
##############################################################################
##############################################################################

class Pir(object):
  def __init__(self, callback):
    print "intializing PIR"
    self.gpio = GpioSettings()
    if not self.gpio.piFunctionsLoaded():
      return
    self.gpio.gpio().setup(self.gpio.PIR_PIN, gpio.IN)
    self.gpio.gpio().add_event_detect(self.gpio.PIR_PIN, gpio.RISING, callback=callback, bouncetime=300)

##############################################################################
##############################################################################
##############################################################################


import os
import sys
sys.path.append(os.path.abspath("/home/pi/garageMonitor/django/lib"))
#from gpioSettings import GpioSettings
from osUtils import checkUser
#from piPir import Pir

def pirCallback(channel):
  print "Motion Detected on " + str(channel)

if __name__ == "__main__":
  checkUser()
  print "initializing gpio now"
  gpio = GpioSettings()
  if gpio.piFunctionsLoaded():
    print "loaded here"
    pir = Pir(pirCallback)
  else:
    print "not loaded"

And it works fine!!??!!!

sudo python startPio.py
initializing gpio now
starting to initialize gpio settings
initializing gpio settings now
loaded here
intializing PIR
starting to initialize gpio settings
gpio settings already initialized now

Answer 1

I gave up. Thanks to Corley Brigman, here is what I wound up with:

piPir.py:

    import os
    import sys
    sys.path.append(os.path.abspath("/home/pi/garageMonitor/django/lib"))
    import gpioSettings
    import RPi.GPIO as GPIO
    GPIO.setmode(GPIO.BCM)

class Pir(object):
  def __init__(self, callback):
    GPIO.setup(gpioSettings.PIR_PIN, GPIO.IN)
    GPIO.add_event_detect(gpioSettings.PIR_PIN, GPIO.RISING, callback=callback, bouncetime=300)

gpioSettings.py:

PIR_PIN = 6
DOOR_UP_PIN = 21
DOOR_DOWN_PIN = 22

gpioStart.py:

import os
import sys
import time
sys.path.append(os.path.abspath("/home/pi/garageMonitor/django/lib"))
from osUtils import checkUser
from piPir import Pir
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)

def pirCallback(channel):
  print "Motion Detected on " + str(channel)

if __name__ == "__main__":
  checkUser()
  pir = Pir(pirCallback)
  time.sleep(30000)