How do i reach a class from within another class?

I have
Class A and
Class B

How can i activate or run class A from Class B?

example, if class A and class B work toward the same resource, one create data the other consume data. How can i make class A creator start again and create more data?

Something like this may do ...

class A:
    def __init__(self, num=1):
        self.strA = '<>' * num

class B:
    def __init__(self):
        # create an instance of class A within class B
        a = A()
        print(a.strA)  # <>
        a = A(3)
        print(a.strA)  # <><><>
        a = A(5)
        print(a.strA)  # <><><><><>

b = B()

Remember that i am a newbie.

I didnt understand that example, i will post some code here that i have worked with, i need help here please. I have a problem that i cant solve.

How do i make the C wait or hinder it from start if there is a chance that data_list will run dry? less then 0

Keep it simple please and i dont want to use a que if that is possible. I have worked with this many days and i cant fix it.

import time
import random
from threading import Thread, Lock


def start():
    
    global lock		
    global data_list  
    
    lock = Lock()
    
    data_list = 0		

    thread1 = P()
    thread1.start()
    
    thread2 = C()
    thread2.start()
    

class P(Thread):
    
	def run(self):
	
	    global data_list
	    
	    lock.acquire()
	

	
	    
	    n = random.randint(0, 99)
	    print n, 
	    
	    while n >= 0:
		x = random.randint(0,99) 
		print x,
		data_list = data_list +x
		time.sleep(.30) 
		n = n-1
	    
	    
	    print "-"*60
	    
	    print( data_list ),
	    
	
	    lock.release()
	

    
class C(Thread):
    
   
    	def run(self):
	
	    global data_list
	
	    lock.acquire()
	
	    
	    print "-"*60
	    
	
	    m = random.randint(0, 99)
	    
	    print m,
	    
	    
	    while m >= 0:
		x = random.randint(0,99)
		print x,	
		data_list = data_list -x
		time.sleep(.15)
		m = m-1
		
	    print ""
	    print "-"*60
	  
	    print( data_list ),
		
		
	    lock.release()
	
	
if __name__ == '__start__':
	start()

First of all, you are mixing tabs and spaces in your code indentations. The program editor I am using absolutely hates this. Please stick with the customary 4 spaces, you will gain from it in the long run.

Also, since your data_list is not a list there is no chance that it will "run dry", or is data_list just a poorly named variable?

What is this code supposed to accomplish?
What does it have to do with the title of this thread?

First of all, you are mixing tabs and spaces in your code indentations. The program editor I am using absolutely hates this. Please stick with the customary 4 spaces, you will gain from it in the long run.

Also, since your data_list is not a list there is no chance that it will "run dry", or is data_list just a poorly named variable?

What is this code supposed to accomplish?
What does it have to do with the title of this thread?

It have nothing to do with the title i guess, except maybe how you make a function in class c that will start the class/thread p.

The program are supposed to create data in a global variable with p thread. The c thread are supposed to remove data from the same variable...the problem i have :

How do you stop the c thread from removing data / subtract data if from getting a negative value = variable empty. Its hard for me to explain.

Are you describing a "race condition"? If you are working with something like this you are not a newbie, this is complex stuff.

try googling "data race condition" and learn about the different methods to solve this fundamental software design issue.

mhh!... I see only two ways of mixing two classes. Making an instance of Class A in class B as Vega have already done or Inherit class A into B and use the methods as Local to the class.

The program are supposed to create data in a global variable with p thread. The c thread are supposed to remove data from the same variable...the problem i have :

How do you stop the c thread from removing data / subtract data if from getting a negative value = variable empty. Its hard for me to explain.

+1 for jlm699
These are'nt new bee stuffs!