python, cache, decorator

cache.py

def cache(func):
    attr = '_cls_cache_'
    def wrapper(*args, **kwargs):
        cls = args[0]
        key = str(args[1:]) + str(kwargs)

        if not hasattr(cls, attr):
            setattr(cls, attr, {})

        _cache = getattr(cls, attr)

        if key in _cache:
            return _cache[key]

        _cache[key] = func(*args, **kwargs)
        return _cache[key]

        func(*args)
    return wrapper


class Example:
    @cache
    def my_big_o_2(self, input):
        for ... in ...:
          for ... in ...:
        return something
      
    def my_entry_func(self):
      self.my_big_o_2('my_input')