A solution that fails a circular reference (import) in the Python language

Recently in the development of the Smart Home Project Hestia-rpi project, due to the unreasonable hierarchy of code structure, the circular reference (import) module failed, the error is as follows:

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Traceback (most recent call last):  File "./main.py", line 8, in <module>    from hestiarpi.library.server import server  File "/home/pi/server/hestiarpi/library/server/server.py", line 4, in <module>    from hestiarpi.library.brain import handler  File "/home/pi/server/hestiarpi/library/brain/handler.py", line 5, in <module>    from hestiarpi.library.brain import monitor  File "/home/pi/server/hestiarpi/library/brain/monitor.py", line 6, in <module>    from hestiarpi.library.server import serverImportError: cannot import name server

Principle

There is a problem at this time, the current script Main execution, need to execute from a import, found that no A, a new A in memory, and then populate the information of a module, will go to execute a, at this time, a inside to from Main import D, So because main has been executed, directly from the memory of the map to get the main information, but at this time the main information has not been filled, because the previous is to fill before the move to a, then from the existing empty main can not get D, will error, importerror.

From: 75089682

Solution Plan A reasonable division of the project Code level

The most fundamental problem of circular reference is that the hierarchy of code is unreasonable, so the most basic and reasonable solution is to re-partition the hierarchy of code, rationalize it, and naturally evade the trouble of circular reference.

Scenario two refers only to the current package and does not refer to a specific module

If your code is this way, it works.

Before modification

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# a.py from b Import b  def a ():      pass  # some codes  # b.py from a import a  def b ():      a.a ()   #some codes

After modification

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# a.pyfromB import b def a():    pass # some codes # b.pyimport A def b():    A.a.a()#some codes

Scenario two puts a reference inside a function

If your code is this way, it works.

Before modification

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# a.py from b Import b  def a ():      pass  # some codes  # b.py from a import a  def b ():      a.a ()   #some codes

After modification

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# a.py from b import b  def a ():       pass  # some codes  # b.py   def Code class= "Python Plain" >b ():      from a import a      a.a ()   #some codes

Source: Hu Xiaoxu = a solution that fails the circular reference (import) in the Python language

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A solution that fails a circular reference (import) in the Python language