Python 找不到 class 属性

Question

为什么 Factory.rdyq 对继承类不可见？

bar.py

import Queue
import threading



class Factory:
    name = ""
    rdyQ = Queue.Queue()
    dispQ = Queue.Queue()

    def __init__(self):
        self.worker_count = 1
        self.worker_thread = None

    def worker(self): pass

    def initialize(self):
        for i in range(self.worker_count):
            t = threading.Thread(target=self.worker)
            t.daemon = True
            t.start()
            self.worker_thread = t




    @staticmethod
    def joinQ():
        Factory.rdyQ.join()
        Factory.dispQ.join()
        return

    @staticmethod
    def getFactory(factory_name):
        if factory_name == "setup":
            return SetupFactory()
        elif factory_name == "dispatch":
            return DispatchFactory()
        elif factory_name == "complete":
            return CompleteFactory()
        else:
            return None

class SetupFactory(Factory):
    name = "setup"

    def worker(self):
        while True:
            try:
                item = Factory.rdyq.get(timeout=1)
                print "setup: %s" % item
                Factory.rdyq.task_done()

                Factory.dispQ.put(item)
            except Queue.Empty, msg:
                continue

class DispatchFactory(Factory):
    name = "dispatch"

    def worker(self):
        while True:
            try:
                item = Factory.dispQ.get(timeout=1)
                print "dispQ: %s" % item
                Factory.dispQ.task_done()

            except Queue.Empty, msg:
                continue

class CompleteFactory(Factory):
    name = "complete"

    def worker(self):
        for i in range(10):
            Factory.rdyq.put(i)

foo.py

import bar as df

setup = df.Factory.getFactory("setup")
dispatch = df.Factory.getFactory("dispatch")
complete = df.Factory.getFactory("complete")

setup.initialize()
dispatch.initialize()
complete.initialize()

df.Factory.joinQ()

setup.worker_thread.join()
dispatch.worker_thread.join()
complete.worker_thread.join()

python foo.py

  File "/u/bar.py", line 73, in worker
    Factory.rdyq.put(i)
AttributeError: class Factory has no attribute 'rdyq'

Answer 1

您应该使用 classmethod 而不是 joinQ 的 staticmethod。

您还有一个 rdyq（bar.py 最后一行）而不是预期的 rdyQ 并且 Python 区分大小写。

bar.py

import Queue
import threading



class Factory:
    name = ""
    rdyQ = Queue.Queue()
    dispQ = Queue.Queue()

    def __init__(self):
        self.worker_count = 1
        self.worker_thread = None

    def worker(self): pass

    def initialize(self):
        for i in range(self.worker_count):
            t = threading.Thread(target=self.worker)
            t.daemon = True
            t.start()
            self.worker_thread = t




    @classmethod
    def joinQ(cls):
        cls.rdyQ.join()
        cls.dispQ.join()
        return

    @staticmethod
    def getFactory(factory_name):
        if factory_name == "setup":
            return SetupFactory()
        elif factory_name == "dispatch":
            return DispatchFactory()
        elif factory_name == "complete":
            return CompleteFactory()
        else:
            return None

class SetupFactory(Factory):
    name = "setup"

    def worker(self):
        while True:
            try:
                item = Factory.rdyq.get(timeout=1)
                print "setup: %s" % item
                Factory.rdyq.task_done()

                Factory.dispQ.put(item)
            except Queue.Empty, msg:
                continue

class DispatchFactory(Factory):
    name = "dispatch"

    def worker(self):
        while True:
            try:
                item = Factory.dispQ.get(timeout=1)
                print "dispQ: %s" % item
                Factory.dispQ.task_done()

            except Queue.Empty, msg:
                continue

class CompleteFactory(Factory):
    name = "complete"

    def worker(self):
        for i in range(10):
            Factory.rdyQ.put(i)

Answer 2

Python 变量和属性区分大小写，所以 "rdyq" 与 "rdyQ" 不同。

Answer 3

您将名称设置为大写的 q，所以这也许可以解决问题？

Factory.rdyQ.put(i)

我推荐 using_underscores_for_variables，因为您可以避免驼峰式命名可能导致的问题。

Python 找不到 class 属性

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