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Asked: 2026-05-15T22:06:05+00:00

I’m currently trying to write a multiple-file Python (2.6.5) game using PyGame. The problem

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I’m currently trying to write a multiple-file Python (2.6.5) game using PyGame. The problem is that one of the files, “pyconsole.py”, needs to be able to call methods on instances of other objects imported by the primary file, “main.py”. The problem is that I have a list in the main file to hold instances of all of the game objects (player’s ship, enemy ships, stations, etc.), yet I can’t seem to be able to call methods from that list within “pyconsole.py” despite the fact that I’m doing a from pyconsole import * in “main.py” before the main loop starts. Is this simply not possible, and should I instead use M4 to combine every file into 1 single file and then bytecode-compile and test/distribute that?

Example:

bash$ cat test.py
#!/usr/bin/python

import math, distancefrom00
foo = 5

class BarClass:
    def __init__(self):
        self.baz = 10
    def get(self):
        print "The BAZ is ", self.baz
    def switch(self)
        self.baz = 15
        self.get()

bar = BarClass()

def main():
    bar.switch()
    print distancefrom00.calculate([2, 4])

if __name__ == '__main__': main()

bash$ cat distancefrom00.py
#!/usr/bin/python

import math
import test

def calculate(otherpoint):
    return str(math.hypot(otherpoint[0], otherpoint[1]))+" (foo = "+str(test.foo)+"; "+test.bar.get()+")"

bash$ python test.py
The BAZ is  15
The BAZ is  10
Traceback (most recent call last):
  File "test.py", line 24, in <module>
    if __name__ == '__main__': main()
  File "test.py", line 22, in main
    print distancefrom00.calculate([2, 4])
  File "/home/archie/Development/Python/Import Test/distancefrom00.py", line 8, in calculate
    return str(math.hypot(otherpoint[0], otherpoint[1]))+" (foo = "+str(test.foo)+"; "+test.bar.get()+")"
TypeError: cannot concatenate 'str' and 'NoneType' objects

If my somewhat limited understanding of Python names, classes, and all that stuff is correct here, the NoneType means that the name test.bar.get() – and thus, test.bar – is not assigned to anything.

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1 Answer

  1. Editorial Team

    The problem is that one of the files,
    “pyconsole.py”, needs to be able to
    call methods on instances of other
    objects imported by the primary file,
    “main.py”.

    This just sounds like the dependencies are wrong. Generally nothing should be calling ‘backwards’ up to the main file. That main.py should be the glue that holds everything else together, and nothing should depend on it. Technically the dependencies should form a directed acyclic graph. As soon as you find a cycle in your dependency graph, move out the common aspects into a new file to break the cycle.

    So, move the things in ‘main.py’ that are used by ‘pyconsole.py’ out into a new file. Then have ‘main.py’ and ‘pyconsole.py’ import that new file.

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