python Returning data from a threaded def

Question

I have a bit of code that gets the title of a .MP3 file

def getTitle(fileName):
    print "getTitle"
    audio = MP3(fileName)

    try:
        sTitle = str(audio["TIT2"])
    except KeyError:
        sTitle = os.path.basename(fileName)

    sTitle = replace_all(sTitle) #remove special chars

    return sTitle

I would call this function with

sTitle = getTitle("SomeSong.mp3")

To solve another problem I wanted to spawn this on its own thread so I altered my call to

threadTitle = Thread(target=getTitle("SomeSong.mp3"))
threadTitle.start()

This correctly calls the function and solves my other problem, but now I can't figure out how to get the return value of sTitle from the function into Main.

Answer 1

I would make a new object that extends thread so that you can get anything you want out of it at any time.

from threading import Thread

class GetTitleThread(Thread):        

    def __init__(self, fileName):
        self.sTitle = None
        self.fileName = fileName
        super(GetTitleThread, self).__init__()

    def run(self):
        print "getTitle"
        audio = MP3(self.fileName)

        try:
            self.sTitle = str(audio["TIT2"])
        except KeyError:
            self.sTitle = os.path.basename(self.fileName)

        self.sTitle = replace_all(self.sTitle) #remove special chars


if __name__ == '__main__':
    t = GetTitleThread('SomeSong.mp3')
    t.start()
    t.join()
    print t.sTitle

Answer 2

One way to do it is to use a wrapper storing the result:

def wrapper(func, args, res):
    res.append(func(*args))

res = []
t = threading.Thread(
    target=wrapper, args=(getTitle, ("SomeSong.mp3",), res))
t.start()
t.join()
print res[0]