python中的简单交叉导入

Question

我想将代码放在不同的类中，并将它们放入不同的文件中。但是这些类是相互依赖的。

main.py：

from lib import A, B

def main():
    a = A()
    b = B()
    a.hello()
    b.hello()

if __name__ == '__main__':
    main()

lib / _ 初始化 _.py：

from a import A
from b import B

lib / a.py：

import lib.B

class A():
    def __init__(self):
        print "A"

    def hello(self):
        print "hello A"
        b = B()

lib / b.py：

import lib.A

class B():
    def __init__(self):
        print "B"

    def hello(self):
        print "hello B"
        a = A()

是否可以在Python中做到这一点？

编辑：

我收到此错误消息：

pydev debugger: starting
Traceback (most recent call last):
  File "eclipse-python/plugins/org.python.pydev_2.7.1.2012100913/pysrc/pydevd.py", line 1397, in <module>
    debugger.run(setup['file'], None, None)
  File "eclipse-python/plugins/org.python.pydev_2.7.1.2012100913/pysrc/pydevd.py", line 1090, in run
    pydev_imports.execfile(file, globals, locals) #execute the script
  File "main.py", line 2, in <module>
    from lib import A, B
  File "lib/__init__.py", line 1, in <module>
    from a import A
  File "lib/a.py", line 1, in <module>
    import lib.B
ImportError: No module named B

Answer 1

您可以在hello函数中导入其他模块，而不必在顶部导入模块。

class B():
    def __init__(self):
        print "B"

    def hello(self):
        import lib.A
        print "hello B"
        a = A()