backboneelement introduced cyclical import as of 8fe3dbcd

[mmabey]

• fhir.resources version: 5.1.1.dev0
• Python version: 3.6.9
• Operating System: MacOS

Description

In 8fe3dbcd, when Black was used on the code and unified the import statements, the import of extension was moved from the bottom of the file to the top. Any code that uses backboneelement.BackboneElement (in my case an OperationOutcome) now triggers a cyclical import as can be seen in the attached screenshot. Briefly:

• backboneelement imports extension
• extension imports annotation
• annotation imports fhirreference
• fhirreference imports bundle
• bundle attempts to import backboneelement, which technically succeeds, but since the first import of backboneelement hasn't completed, the BackboneElement class isn't available and the import in bundle fails.

Expected behavior is for an import of operationoutcome.OperationOutcome to succeed.

What I Did

Text version of the attached image:

     from fhir.resources.DSTU2.operationoutcome import OperationOutcome
   File "/home/app/.local/share/virtualenvs/ehr-TNUJx0lF/lib/python3.6/site-packages/fhir/resources/DSTU2/operationoutcome.py", line 8, in <module>
     from . import backboneelement, codeableconcept, domainresource
   File "/home/app/.local/share/virtualenvs/ehr-TNUJx0lF/lib/python3.6/site-packages/fhir/resources/DSTU2/backboneelement.py", line 8, in <module>
     from . import element, extension
   File "/home/app/.local/share/virtualenvs/ehr-TNUJx0lF/lib/python3.6/site-packages/fhir/resources/DSTU2/extension.py", line 8, in <module>
     from . import (address, annotation, attachment, codeableconcept, coding,
   File "/home/app/.local/share/virtualenvs/ehr-TNUJx0lF/lib/python3.6/site-packages/fhir/resources/DSTU2/annotation.py", line 8, in <module>
     from . import element, fhirdate, fhirreference
   File "/home/app/.local/share/virtualenvs/ehr-TNUJx0lF/lib/python3.6/site-packages/fhir/resources/DSTU2/fhirreference.py", line 116, in <module>
     from . import bundle
   File "/home/app/.local/share/virtualenvs/ehr-TNUJx0lF/lib/python3.6/site-packages/fhir/resources/DSTU2/bundle.py", line 64, in <module>
     class BundleEntry(backboneelement.BackboneElement):
 AttributeError: module 'fhir.resources.DSTU2.backboneelement' has no attribute 'BackboneElement'

[nazrulworld]

@mmabey please do merge request on https://github.com/nazrulworld/fhir.resources/tree/5.X.X 5.X.X branch

[mmabey]

As I mentioned in #12, the recent refactor has removed this bug.