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  1. from itertools import chain
  2. from weakref import WeakSet
  3. import operator
  4.  
  5. class Dynamic:
  6.     @classmethod
  7.     def args(self, *args, **kw):
  8.         return lambda f: Dynamic(f, *args, **kw)
  9.  
  10.     def __init__(self, f, *args, **kw):
  11.         self._ismodified = True
  12.         self._cache = None
  13.  
  14.         self.thunk = lambda: None, (), {}
  15.         self.children = WeakSet()  # тут надо немного посидеть с дебагером
  16.         self.parents = set()       # и убедиться что нет утечек памяти
  17.  
  18.         self.update(f, *args, **kw)
  19.  
  20.     def update(self, f, *args, **kw):
  21.         try:
  22.             thunk = f.thunk
  23.             parents = set(f.parents)
  24.  
  25.         except AttributeError:
  26.             thunk = f, args, kw
  27.             parents = set(chain(args, kw.values()))
  28.  
  29.         if self in parents:              # возможно это можно обработать лучше
  30.             parents.discard(self)
  31.             oldself = Dynamic(self)      # fork self
  32.  
  33.             f, args, kw = thunk
  34.             args = list(args)
  35.  
  36.             for i, a in enumerate(args):  # patch thunk
  37.                 if a is self:
  38.                     args[i] = oldself
  39.  
  40.             for k, v in kw.items():
  41.                 if v is self:
  42.                     kw[k] = oldself
  43.  
  44.             thunk = f, tuple(args), kw
  45.             parents.add(oldself)
  46.  
  47.         for p in parents:
  48.             p.children.add(self)
  49.  
  50.         for p in self.parents:
  51.             p.children.discard(self)
  52.  
  53.         self.thunk = thunk
  54.         self.parents = parents
  55.         self.setmodified()
  56.  
  57.     def setmodified(self):
  58.         if not self._ismodified:
  59.             self._ismodified = True
  60.  
  61.             for c in self.children:
  62.                 c.setmodified()
  63.  
  64.     def compose(self, f, d):
  65.         return Dynamic(f, self, d)
  66.  
  67.     def __get__(self, obj, type=None):
  68.         return self
  69.  
  70.     def __set__(self, obj, d):
  71.         self.update(d)
  72.  
  73.     def __call__(self):
  74.         if self._ismodified:
  75.             self._ismodified = False
  76.             f, args, kw = self.thunk
  77.  
  78.             self._cache = f(
  79.                 *[d() for d in args],
  80.                 **{k: v() for k, v in kw}
  81.                 )
  82.  
  83.         return self._cache
  84.  
  85.     def __hash__(self):
  86.         return id(self)
  87.  
  88.     def __repr__(self):
  89.         return 'Dynamic({}:{})'.format(hash(self), repr(self()))
  90.  
  91.     def __str__(self):
  92.         return str(self())
  93.  
  94.     def __add__(self, d):
  95.         return self.compose(operator.add, d)
  96.  
  97.     def __mul__(self, d):
  98.         return self.compose(operator.mul, d)
  99.  
  100.     def __truediv__(self, d):
  101.         return self.compose(operator.div, d)
  102.  
  103.     def __iadd__(self, d):
  104.         self.update(self + d)
  105.         return self
  106.  
  107.     def __imul__(self, d):
  108.         self.update(self * d)
  109.         return self
  110.  
  111.     def __itruediv__(self, d):
  112.         self.update(self / d)
  113.         return self
  114.     # и т.д...
  115.     # это всё конечно можно сгенерировать на этапе создания экземпляра класса,
  116.     # но мне влом.
  117.  
  118. x = Dynamic(lambda: 2)
  119. a = Dynamic(lambda: 5)
  120. b = Dynamic(lambda: 2)
  121.  
  122. c = a * b
  123. print('c:', c)
  124.  
  125. a += x
  126. print('c:', c)
  127.  
  128. x.update(lambda: 0)
  129. print('c:', c)
  130.  
  131. @Dynamic.args(c, b)
  132. def d(c, b):
  133.     return c / b
  134.  
  135. print('d:', d)
  136.  
  137. class Table:
  138.     q = Dynamic(lambda: 9)
  139.     w = Dynamic(lambda: 8)
  140.     e = q + w
  141.  
  142. z = Table()
  143. print('z.e', z.e)
  144.  
  145. z.q = Dynamic(lambda: 0)
  146. print('z.e', z.e)
  147.  
Success #stdin #stdout 0.03s 9440KB
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c: 10
c: 14
c: 10
d: 5.0
z.e 17
z.e 8
https://ideone.com/trqwzk
language:
Python 3 (python  3.12)
created:
11 years ago
visibility:
public

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