python - 将字符串转换为 Python 对象

Question

几周前我刚刚开始学习 Python，并开始编写一个基于文本的冒险游戏。除了使用 eval() 之外，我在寻找将字符串转换为类实例的好方法时遇到了一些麻烦，我读过 eval() 并不安全。作为引用，这是我正在处理的内容:

class Room(object):
    """Defines a class for rooms in the game."""
    def __init__(self, name, unlocked, items, description, seen):
        self.name = name
        self.unlocked = unlocked
        self.items = items
        self.description = description
        self.seen = seen


class Item(object):
    """ Defines a class of items in rooms."""
    def __init__(self, name, actions, description):
        self.name = name
        self.actions = actions
        self.description = description



def examine(input):
    if isinstance(eval(input), Room):
        print eval(input).description
    elif isinstance(eval(input), Item):
        print eval(input).description
    else:   
        print "I don't understand that."

如果输入是字符串，如何安全地将其设为类对象并访问数据属性.description？另外，如果我以完全错误的方式解决这个问题，请随时提出替代方案!

Answer 1

使用字典:

lookup = {'Room': Room(), 'Item': Item()}
myinstance = lookup.get(input)
if myinstance is not None:
    print myinstance.description