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  1. import contextlib
  2. import unittest
  3.  
  4. class SafeContextMixin:
  5. 	def __init__(self, *args, **kwargs):
  6. 		with contextlib.ExitStack() as es:
  7. 			init = self._safe_init(*args, **kwargs)
  8. 			ret = None
  9. 			while True:
  10. 				try:
  11. 					ret = es.enter_context(init.send(ret))
  12. 				except StopIteration:
  13. 					break
  14. 			self.__exit_stack = es.pop_all()
  15. 	def __enter__(self):
  16. 		return self
  17. 	def __exit__(self, et, ev, eb):
  18. 		self.close()
  19. 	def close(self):
  20. 		self.__exit_stack.close()
  21.  
  22. # test
  23.  
  24. @contextlib.contextmanager
  25. def good():
  26. 	print("good init")
  27. 	try:
  28. 		yield 42
  29. 	finally:
  30. 		print("good close")
  31.  
  32. @contextlib.contextmanager
  33. def bad():
  34. 	print("bad init")
  35. 	raise Exception("bad")
  36.  
  37. class Foo(SafeContextMixin):
  38. 	def _safe_init(self, m1, m2):
  39. 		self.f1 = yield m1()
  40. 		self.f2 = yield m2()
  41.  
  42. def test(m1, m2):
  43. 	print("---")
  44. 	try:
  45. 		print("Before with")
  46. 		with Foo(m1, m2) as f:
  47. 			print("Inside with")
  48. 		print("After with")
  49. 	except Exception as e:
  50. 		print("Caugth :", e)
  51.  
  52. test(good, good)
  53. test(good, bad)
  54. test(bad, bad)
  55.  
Success #stdin #stdout 0.03s 29808KB
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stdin
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Standard input is empty
stdout
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---
Before with
good init
good init
Inside with
good close
good close
After with
---
Before with
good init
bad init
good close
Caugth : bad
---
Before with
bad init
Caugth : bad
https://ideone.com/GAQG5i
language:
Python 3 (python  3.12)
created:
7 years ago
visibility:
secret

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