How to get the return value from a thread using python?

Question

How to get the value 'foo' which is returned from the thread as shown below?

from threading import Thread

def foo(bar):

    print 'hello {}'.format(bar)

    return 'foo'

thread = Thread(target=foo, args=('world!',))

thread.start()

ret = thread.join()

print ret

 Returns None in the above case.

Answer 1

You can do it by using a queue. I have included the code to create a simple queue wrapper over an existing list, which you can modify if you wish. You can also use some other queue library as well.

Here you do not need to change the code that you wrote just add a queue as i have and it should work.

from threading import Thread

class Queue:

    def __init__(self):

        self.queue = []

    def enqueue(self, data):

        self.queue.append(data)

    def dequeue(self, data):

        data = None

        try:

            data = self.queue.pop(0)

        catch IndexError as ex:

            pass

        return data

    def is_empty(self):

        return len(self.queue) == 0

def foo(bar):

    print 'hello {0}'.format(bar)

    return 'foo'

q = Queue()

t = Thread(target=lambda q, arg: q.enqueue(foo(arg)), args=(q, 'world!'))

t.start()

t.join()

result = que.get()

print(result)

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