1# -*- coding: utf-8 -*- 

2from __future__ import annotations 

3 

4# -- stdlib -- 

5from typing import Sequence, Type 

6import sys 

7 

8# -- third party -- 

9# -- own -- 

10 

11 

12# -- code -- 

13class ViralContext(object): 

14 VIRAL_SEARCH = ['self'] 

15 CONTINUE = object() 

16 

17 _viral_mro_cache: Sequence[Type[ViralContext]] = [] 

18 

19 def __new__(cls: Type[ViralContext], *a, **k): 

20 self = object.__new__(cls) 

21 cache = cls._viral_mro_cache if '_viral_mro_cache' in cls.__dict__ else None 

22 if not cache: 

23 cache = [c for c in cls.mro() if ViralContext in c.__bases__] 

24 cls._viral_mro_cache = cache 

25 

26 for c in cache: 

27 that = c.viral_search(start=2) if cls.VIRAL_SEARCH else None 

28 c.viral_import(self, that.viral_export() if that else None) 

29 

30 return self 

31 

32 @classmethod 

33 def viral_search(cls, start=1): 

34 f = sys._getframe(start) or None 

35 while f: 

36 for name in cls.VIRAL_SEARCH: 

37 that = f.f_locals.get(name) 

38 if that is not None and isinstance(that, cls): 

39 return that 

40 

41 f = f.f_back 

42 

43 return None 

44 

45 def viral_import(self, env): 

46 raise Exception('Override this!') 

47 

48 def viral_export(self): 

49 raise Exception('Override this!')