循环中带有超时的用户输入 [英] User input with a timeout, in a loop
问题描述
我正在尝试创建一个循环python函数，该函数执行任务并提示用户响应，如果用户在给定时间内未响应，则该序列将重复.
I'm trying to create a looping python function which performs a task and prompts the user for a response and if the user does not respond in the given time the sequence will repeat.
这大致是基于以下问题:如何在raw_input上设置时间限制
This is loosely based off this question: How to set time limit on raw_input
该任务由some_function()表示.超时是一个以秒为单位的变量.以下代码有两个问题:
The task is represented by some_function(). The timeout is a variable in seconds. I have two problems with the following code:
-
raw_input提示符在指定的4秒钟后不会超时，无论用户是否提示.
The raw_input prompt does not timeout after the specified time of 4 seconds regardless of whether the user prompts or not.
当输入'q'的raw_input时(不包含"，因为我知道键入的任何内容都会自动输入为字符串)，该函数不会退出循环.
When raw_input of 'q' is entered (without '' because I know anything typed is automatically entered as a string) the function does not exit the loop.
`
import thread
import threading
from time import sleep
def raw_input_with_timeout():
prompt = "Hello is it me you're looking for?"
timeout = 4
astring = None
some_function()
timer = threading.Timer(timeout, thread.interrupt_main)
try:
timer.start()
astring = raw_input(prompt)
except KeyboardInterrupt:
pass
timer.cancel()
if astring.lower() != 'q':
raw_input_with_timeout()
else:
print "goodbye"
`
推荐答案
警告:旨在按要求在* nix和OSX中工作，但绝对不能在Windows中工作.
Warning: This is intended to work in *nix and OSX as requested but definitely will not work in Windows.
我已经使用此修改作为ActiveState配方的基础下面的代码.这是一个易于使用的对象，可以读取带有超时的输入.它使用轮询一次收集一个字符并模拟raw_input()/input()的行为.
I've used this modification of an ActiveState recipe as a basis for the code below. It's an easy-to-use object that can read input with a timeout. It uses polling to collect characters one at a time and emulate the behavior of raw_input() / input().
注意:显然以下_getch_nix()方法不适用于OP，但对OSX 10.9.5而言适用.您可能会很幸运地调用_getch_osx()，尽管它似乎只能在32位python中工作，因为Carbon不完全支持64位.
Note: apparently the _getch_nix() method below doesn't work for OP but it does for me on OSX 10.9.5. You might have luck calling _getch_osx() instead although it seems to work in 32-bit python only since Carbon doesn't fully support 64-bit.
import sys
import time
class TimeoutInput(object):
def __init__(self, poll_period=0.05):
import sys, tty, termios # apparently timing of import is important if using an IDE
self.poll_period = poll_period
def _getch_nix(self):
import sys, tty, termios
from select import select
fd = sys.stdin.fileno()
old_settings = termios.tcgetattr(fd)
try:
tty.setraw(sys.stdin.fileno())
[i, o, e] = select([sys.stdin.fileno()], [], [], self.poll_period)
if i:
ch = sys.stdin.read(1)
else:
ch = ''
finally:
termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
return ch
def _getch_osx(self):
# from same discussion on the original ActiveState recipe:
# http://code.activestate.com/recipes/134892-getch-like-unbuffered-character-reading-from-stdin/#c2
import Carbon
if Carbon.Evt.EventAvail(0x0008)[0] == 0: # 0x0008 is the keyDownMask
return ''
else:
# The event contains the following info:
# (what,msg,when,where,mod)=Carbon.Evt.GetNextEvent(0x0008)[1]
#
# The message (msg) contains the ASCII char which is
# extracted with the 0x000000FF charCodeMask; this
# number is converted to an ASCII character with chr() and
# returned
(what,msg,when,where,mod)=Carbon.Evt.GetNextEvent(0x0008)[1]
return chr(msg & 0x000000FF)
def input(self, prompt=None, timeout=None,
extend_timeout_with_input=True, require_enter_to_confirm=True):
"""timeout: float seconds or None (blocking)"""
prompt = prompt or ''
sys.stdout.write(prompt) # this avoids a couple of problems with printing
sys.stdout.flush() # make sure prompt appears before we start waiting for input
input_chars = []
start_time = time.time()
received_enter = False
while (time.time() - start_time) < timeout:
# keep polling for characters
c = self._getch_osx() # self.poll_period determines spin speed
if c in ('\n', '\r'):
received_enter = True
break
elif c:
input_chars.append(c)
sys.stdout.write(c)
sys.stdout.flush()
if extend_timeout_with_input:
start_time = time.time()
sys.stdout.write('\n') # just for consistency with other "prints"
sys.stdout.flush()
captured_string = ''.join(input_chars)
if require_enter_to_confirm:
return_string = captured_string if received_enter else ''
else:
return_string = captured_string
return return_string
测试
# this should work like raw_input() except it will time out
ti = TimeoutInput(poll_period=0.05)
s = ti.input(prompt='wait for timeout:', timeout=5.0,
extend_timeout_with_input=False, require_enter_to_confirm=False)
print(s)
重复输入
按照我的理解，这可以实现您的初衷.我看不到进行递归调用的任何价值-我认为您想要的只是重复获取输入?如果那是错误的，请纠正我.
Repeated Input
This implements your original intention as I understand it. I don't see any value to making recursive calls - I think what you want is just to get input repeatedly? Please correct me if that is wrong.
ti = TimeoutInput()
prompt = "Hello is it me you're looking for?"
timeout = 4.0
while True:
# some_function()
s = ti.input(prompt, timeout)
if s.lower() == 'q':
print "goodbye"
break
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