lib/observer.py

   1 class ObsInfo:
   2
   3     def __init__(self, mth, sort, args):
   4         self.mth = mth
   5         self.sort = sort
   6         self.args = args
   7
   8     def __repr__(self): return str(self.mth)
   9
  10
  11 class Subject:
  12
  13     def __init__(self):
  14         self.observers = {}
  15
  16     def attach(self, obs_meth, sort=10, rename='', args=None):
  17         args = args or []
  18         onm = rename or obs_meth.__name__
  19         if onm not in self.observers: self.observers[onm] = []
  20         self.observers[onm] += [ObsInfo(obs_meth, sort, args)]
  21         sorted_obs = sorted(self.observers[onm], key=lambda obs: obs.sort)
  22         self.observers[onm] = sorted_obs
  23
  24     def detach(self, obs_meth, lambda_call=None):
  25         if isinstance(obs_meth, str):
  26             onm = obs_meth
  27             observers = [obs for obs in self.observers[onm]
  28                          if obs.mth == lambda_call]
  29         else:
  30             onm = obs_meth.__name__
  31             observers = [obs for obs in self.observers[onm]
  32                          if obs.mth == obs_meth]
  33         if not observers: raise Exception
  34         list(map(self.observers[onm].remove, observers))
  35
  36     def notify(self, meth, *args, **kwargs):
  37         if meth not in self.observers: return  # no obs for this notification
  38         for obs in self.observers[meth][:]:
  39             if obs in self.observers[meth]:  # if an obs removes another one
  40                 try:
  41                     act_args = obs.args + list(args)
  42                     obs.mth(*act_args, **kwargs)
  43                 except SystemError:
  44                     print('Quit')
  45                     import sys; sys.exit()
  46
  47     def observing(self, obs_meth):
  48         if callable(obs_meth): obs_meth = obs_meth.__name__
  49         return obs_meth in self.observers and self.observers[obs_meth]
  50
  51     def destroy(self): self.observers = None
  52
  53
  54 class Observer: pass