How to set time limit on raw_input

The signal.alarm function, on which @jer's recommended solution is based, is unfortunately Unix-only. If you need a cross-platform or Windows-specific solution, you can base it on threading.Timer instead, using thread.interrupt_main to send a KeyboardInterrupt to the main thread from the timer thread. I.e.:

import threadimport threadingdef raw_input_with_timeout(prompt, timeout=30.0):    print(prompt, end=' ')        timer = threading.Timer(timeout, thread.interrupt_main)    astring = None    try:        timer.start()        astring = input(prompt)    except KeyboardInterrupt:        pass    timer.cancel()    return astring

this will return None whether the 30 seconds time out or the user explicitly decides to hit control-C to give up on inputting anything, but it seems OK to treat the two cases in the same way (if you need to distinguish, you could use for the timer a function of your own that, before interrupting the main thread, records somewhere the fact that a timeout has happened, and in your handler for KeyboardInterrupt access that "somewhere" to discriminate which of the two cases occurred).

Edit: I could have sworn this was working but I must have been wrong -- the code above omits the obviously-needed timer.start(), and even with it I can't make it work any more. select.select would be the obvious other thing to try but it won't work on a "normal file" (including stdin) in Windows -- in Unix it works on all files, in Windows, only on sockets.

So I don't know how to do a cross-platform "raw input with timeout". A windows-specific one can be constructed with a tight loop polling msvcrt.kbhit, performing a msvcrt.getche (and checking if it's a return to indicate the output's done, in which case it breaks out of the loop, otherwise accumulates and keeps waiting) and checking the time to time out if needed. I cannot test because I have no Windows machine (they're all Macs and Linux ones), but here the untested code I would suggest:

import msvcrtimport timedef raw_input_with_timeout(prompt, timeout=30.0):    print(prompt, end=' ')        finishat = time.time() + timeout    result = []    while True:        if msvcrt.kbhit():            result.append(msvcrt.getche())            if result[-1] == '\r':   # or \n, whatever Win returns;-)                return ''.join(result)            time.sleep(0.1)          # just to yield to other processes/threads        else:            if time.time() > finishat:                return None

The OP in a comment says he does not want to return None upon timeout, but what's the alternative? Raising an exception? Returning a different default value? Whatever alternative he wants he can clearly put it in place of my return None;-).

If you don't want to time out just because the user is typing slowly (as opposed to, not typing at all!-), you could recompute finishat after every successful character input.

I found a solution to this problem in a blog post. Here's the code from that blog post:

import signalclass AlarmException(Exception):    passdef alarmHandler(signum, frame):    raise AlarmExceptiondef nonBlockingRawInput(prompt='', timeout=20):    signal.signal(signal.SIGALRM, alarmHandler)    signal.alarm(timeout)    try:        text = raw_input(prompt)        signal.alarm(0)        return text    except AlarmException:        print '\nPrompt timeout. Continuing...'    signal.signal(signal.SIGALRM, signal.SIG_IGN)    return ''

Please note: this code will only work on *nix OSs.

The input() function is designed to wait for the user to enter something (at least the [Enter] key).

If you are not dead set to use input(), below is a much lighter solution using tkinter. In tkinter, dialog boxes (and any widget) can be destroyed after a given time.

Here is an example :

import tkinter as tkdef W_Input (label='Input dialog box', timeout=5000):    w = tk.Tk()    w.title(label)    W_Input.data=''    wFrame = tk.Frame(w, background="light yellow", padx=20, pady=20)    wFrame.pack()    wEntryBox = tk.Entry(wFrame, background="white", width=100)    wEntryBox.focus_force()    wEntryBox.pack()    def fin():        W_Input.data = str(wEntryBox.get())        w.destroy()    wSubmitButton = tk.Button(w, text='OK', command=fin, default='active')    wSubmitButton.pack()# --- optionnal extra code in order to have a stroke on "Return" equivalent to a mouse click on the OK button    def fin_R(event):  fin()    w.bind("<Return>", fin_R)# --- END extra code ---     w.after(timeout, w.destroy) # This is the KEY INSTRUCTION that destroys the dialog box after the given timeout in millisecondsd    w.mainloop()W_Input() # can be called with 2 parameter, the window title (string), and the timeout duration in milisecondsif W_Input.data : print('\nYou entered this : ', W_Input.data, end=2*'\n')else : print('\nNothing was entered \n')