pyparsing.py 文件源码

def __init__(self):
            cache = {}
            self.not_in_cache = not_in_cache = object()

            def get(self, key):
                return cache.get(key, not_in_cache)

            def set(self, key, value):
                cache[key] = value

            def clear(self):
                cache.clear()

            def cache_len(self):
                return len(cache)

            self.get = types.MethodType(get, self)
            self.set = types.MethodType(set, self)
            self.clear = types.MethodType(clear, self)
            self.__len__ = types.MethodType(cache_len, self)