How to pass a variable by name to a Thread in Python?

Question

Say that I have a function that looks like:

def _thread_function(arg1, arg2=None, arg3=None):
    #Random code

Now I want to create a thread using that function, and giving it arg2 but not arg3. I'm trying to this as below:

#Note: in this code block I have already set a variable called arg1 and a variable called arg2
threading.Thread(target=self._thread_function, args=(arg1, arg2=arg2), name="thread_function").start()

The above code gives me a syntax error. How do I fix it so that I can pass an argument to the thread as arg2?

Solution 1

Use the kwargs parameter:

threading.Thread(target=self._thread_function, args=(arg1,),
                 kwargs={'arg2':arg2}, name='thread_function').start()

Solution 2

you can also use lambda to pass args

threading.Thread(target=lambda: self._thread_function(arg1, arg2=arg2, arg3=arg3)).start()