Python : Passing function as parameter and multithreading

Question

I'm new with python and I can't find why the "Without_thread" class works and not the "With_thread" class.

The purpose of my "With_thread" class is to launch a new thread when I call it with a function so I can execute any function at the same time. (<==This is what I would like to do)

import threading

class With_thread(threading.Thread):
    def __init__(self, target, *args):
        self._target = target
        self._args = args
        threading.Thread.__init__(self)

    def run(self):
        self._target(*self._args)

The "Without_thread" is almost the same class, the only thing changing here is that I don't use threads.

class Without_thread():
    def __init__(self, target, *args):
        self._target = target
        self._args = args

    def foo(self):
        self._target(*self._args)

I test my code with this:

def some_Func(data, key):
    print("some_Func was called : data=%s; key=%s" % (str(data), str(key)))

f1 = With_thread(some_Func, [1,2], 6)
f1.start()
f1.join() 

f2 = Without_thread(some_Func, [1,2], 6)
f2.foo()

The output from f1 is:

    self._target(*self._args)
TypeError: 'NoneType' object is not callable

The output from f2 is:

some_Func was called : data=[1, 2]; key=6

I would really appreciate if you can help me with this, and thank you very much for your time!!!

Tom Dalton · Accepted Answer · 2014-07-23 10:22:18Z

2

I suspect the issue is caused by some sort of conflict between your _target and _args and the same attributes defined within Thread.

You don't need to define __init__() or run() in With_thread. The Thread classes own init allows you to pass keyword arguments target and args, and its run() method will run target with args and kwargs provided at intiialisation.

So, you can get rid of With_thread entirely, and then call:

f1 = threading.Thread(target=some_Func, args=([1,2], 6))

answered Jul 23, 2014 at 10:22

Tom Dalton

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5 Comments

Trimax Over a year ago

I tried changing the name of the args passed to the thread and the exception jumps. To narrowing the issue, if I print the type of _target is 'NoneType' and it should be <class 'function'>

Tom Dalton Over a year ago

Ok, we can come back to that. Does my suggestion work? If so, why do you want to subclass Thread?

Trimax Over a year ago

your solutions works fine. I'm only asking for the reason of why don't works as Rotsap wrote it.

Tom Dalton Over a year ago

Good question, it works fine for me on python 2.7/x64

Akshay Salvi Over a year ago

in some_Func what values should be their

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