Python 将参数传递给线程 class

Question

Python初学者提问。我在这里看到了很多使用 "old" 方法创建线程的示例，但没有看到太多关于如何将参数传递给线程 class 的示例。我的代码如下所示......我尝试了多种不同的方法但还没有运气。非常感谢任何帮助

class downloadToWorldThread (threading.Thread):
    def __init__(self, threadID, name, counter,args=(arg1,arg2,arg3)): 
        threading.Thread.__init__(self)
        self.threadID = threadID
        self.name = name
        self.counter = counter
        self.args.arg1 = arg1
        self.args.arg2 = arg2

        ## or this?
        #self.args.arg1 = args.arg1
        #self.args.arg2 = arg2.arg2

    def run(self):
        ##how do i access individual args?
        print "Starting " + self.name
        print "arg is " +  self.args.arg2

        downloadToMyHouse(self.args.arg1,self.args.arg2,self.args.arg3)
        print "Exiting " + self.name



def downloadAllToWorld(aaa,bbb,ccc,ddd,eee,fff):

    # Create new threads
    ##thread
    thread1 = downloadToWorldThread(1, "blah1-1", 1,args=(arg1,arg2,arg3))
    ##thread2
    thread2 = downloadToWorldThread(2, "blah2-2", 2, args=(arg1,arg2,arg3))

Answer 1

我不确定我是否理解您为什么要为线程创建一个新的 sub-class。但是如果你想将 args 传递给子类，你应该做一些事情：

class downloadAllToWorldThread(threading.Thread):
    def __init__(self, threadID, name, counter, *args):
        threading.Thread.__init__(self)
        self.threadID = threadID
        self.name = name
        self.counter = counter
        self.args = args
    def run(self):
        print('Args are: {}'.format(self.args))
        downloadToMyHouse(self.args[0],self.args[1],self.args[2])

def downloadAllToWorld(aaa,bbb,ccc,ddd,eee):
    thread1 = downloadAllToWorldThread(1,"blah1-1", 1, ccc, ddd, eee)

args 用于在参数数量未知时将参数传递给函数。在这种情况下，作为 args 列表传递的值是： ccc, ddd, eee 。请注意 args 是参数列表，因此您只需使用“[ ]”即可访问其元素。

Answer 2

你在这里试图做的是向你的 downloadAllToWorldThread 传递一个参数列表，引用自 Python docs:

4.7.3. Arbitrary Argument Lists Finally, the least frequently used option is to specify that a function can be called with an arbitrary number of arguments. These arguments will be wrapped up in a tuple (see Tuples and Sequences). Before the variable number of arguments, zero or more normal arguments may occur.
def write_multiple_items(file, separator, *args):
   file.write(separator.join(args))

因此，在您的代码中，您应该执行如下操作：

class downloadToWorldThread (threading.Thread):
    def __init__(self, threadID, name, counter,*args): 
        threading.Thread.__init__(self)
        self.threadID = threadID
        self.name = name
        self.counter = counter
        self.args = args

然后将 self.args 原样传递给 downloadToMyHouse 方法。

def run(self):
        print('Args are: {}'.format(self.args))
        downloadToMyHouse(self.args)

最后，在downloadToMyHouse方法中，打包self.args，例子：

def downloadToMyHouse(self, *args):

    for i in args:
        print i
    #OR
    print args[0] #access specific element of args through indexing

并且当您创建实例时，无需用括号将参数括起来：

thread1 = downloadToWorldThread(1, "blah1-1", 1, arg1, arg2, arg3)

演示：

class myThread(threading.Thread):
    def __init__(self, threadID, name, counter, *args):
        threading.Thread.__init__(self)
        self.threadID = threadID
        self.name = name
        self.counter = counter
        self.args = args
    def run(self):
        print 'Starting Thread {0} named {1}, counter {2}'.format(self.threadID, self.name, self.counter)
        for i in self.args:
            print i


>>> t1 = myThread(1, 'Thread1', 2, 'ONE','TWO','THREE')
>>> t1.start()
Starting Thread 1 named Thread1, counter 2
>>> 
ONE
TWO
THREE

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