Python、"If if line is called on first time, do something else"

Question

所以标题很容易解释，但我会更详细地介绍。我正在创建一个依赖文本的游戏，我将拥有数百万个区域。每次你进入一个新的区域，迎接你的只是一次与你之后再次进入同一个地方不同的反应，我需要找到一种方法来解决这个问题：

if len(line) == 1:
    do exclusive thing
else:
    do normal thing

当然，我可以使用像 "a = 0" 这样的计数器系统，但是我需要为我创建的每个区域创建一个单独的计数器，我不希望那样。

Answer 1

您需要静态变量：What is the Python equivalent of static variables inside a function?

def static_var(varname, value):
    def decorate(func):
        setattr(func, varname, value)
        return func
    return decorate

@static_var("counter", 0)
def is_first_time():
    is_first_time.counter += 1
    return is_first_time.counter == 1

print(is_first_time())
print(is_first_time())
print(is_first_time())

Answer 2

您可以只存储一个 dict 来跟踪房间访问情况，使用 defaultdict

可能更好

from collections import defaultdict

#Using a defaultdict means any key will default to 0
room_visits = defaultdict(int)

#Lets pretend you had previously visited the hallway, kitchen, and bedroom once each
room_visits['hallway'] += 1
room_visits['kitchen'] += 1
room_visits['bedroom'] += 1

#Now you find yourself in the kitchen again
current_room = 'kitchen'
#current_room = 'basement' #<-- uncomment this to try going to the basement next

#This could be the new logic:
if room_visits[current_room] == 0: #first time visiting the current room
    print('It is my first time in the',current_room)
else:
    print('I have been in the',current_room,room_visits[current_room],'time(s) before')

room_visits[current_room] += 1 #<-- then increment visits to this room

Python、"If if line is called on first time, do something else"

Python, "If if line is called on first time, do something else"

python

counter

numbers

adventure

python-3.x