我如何创建函数来访问在子类python进程的run函数中创建的变量

Question

If I have a python class

from multiprocessing import Process

class A(Process):
    def run(self):
        self.var = "asdf"

    def pprint(self):
        print(self.var)

if __name__ == "__main__":
    foo = A()
    foo.start()
    foo.pprint()
    bar = A()
    bar.pprint()

I get the traceback error

Traceback (most recent call last):
  File "simple.py", line 13, in <module>
    foo.pprint()
  File "simple.py", line 8, in pprint
    print(self.var)
AttributeError: 'A' object has no attribute 'var'

Can I access instance variables that are defined within the run function, with other functions defined in the scope of the class?

Answer 1

from multiprocessing import Process

class A(Process):  
  def __init__(self, value):
    self.var = value  
  def run(self):
    self.var = "asdf"
  def pprint(self):
    print(self.var)


foo = A("asdf")
foo.start()
foo.pprint()
bar = A("qwerty")
bar.pprint()

Answer 2

The run() function is executed in another process and the variable is only created there while pprint() is executed in current process. You can eg use a Manager to get a dict to store data common for all processes or exchange data using pipes or queues (read the documentation about that).