在python3中定义文件描述符-使用pyudev/evdev

Question

我目前正在尝试检测覆盆子pi 3上蓝牙按钮的连接(该部分正常工作)，一旦连接上，检测按钮何时被按下(该部分不工作)。

我已经从evdev提供的代码开始，并试图调整它以供我使用(见下文)，但我无法创建正确的文件描述符来使用select (如果我正确地理解了发生的事情)。

import functools
import pyudev
import evdev
from select import select

context = pyudev.Context()
monitor = pyudev.Monitor.from_netlink(context)
monitor.filter_by(subsystem='bluetooth')
monitor.start()

fds = {monitor.fileno(): monitor}
finalizers = []

while True:
    r, w, x = select(fds, [], [])

    if monitor.fileno() in r:
        r.remove(monitor.fileno())
        for udev in iter(functools.partial(monitor.poll, 0), None):
            devices = [evdev.InputDevice(fn) for fn in evdev.list_devices()]
            for device in devices:
                if device.name.strip() == 'AB Shutter3':
                    if udev.action == u'add':
                        print('Device added: %s' % udev)
                        fds[dev.fd] = device #This here breaks. dev.fd undefined.
                        break
                    if udev.action == u'remove':
                        print('Device removed: %s' % udev)
                        def helper():
                            global fds
                            fds = {monitor.fileno(): monitor}
                        finalizers.append(helper)
                        break

    for fd in r:
        dev = fds[fd]
        for event in dev.read():
            print(event)


    for i in range(len(finalizers)):
        finalizers.pop()()

问题是，当我尝试添加设备时，没有定义dev.fd。我试图定义它，但我不知道如何定义文件描述符。我该怎么做？

Device added: Device('/sys/devices/platform/soc/3f201000.serial/tty/ttyAMA0/hci0/hci0:64')
Traceback (most recent call last):
  File "dev_status.py", line 27, in <module>
    fds = {dev.fd:device} #This here breaks. dev.fd undefined.
NameError: name 'dev' is not defined

其他信息:运行Raspbian Strech & Python 3.5.3的Raspberry Pi 3

此外，这是我关于Stack Overflow的第一个问题，所以如果有任何遗漏或可以更详细的内容，请随时提出。

谢谢,

Pém‘

Answer 1

好了，我已经找到了一个解决方案。这就是它，如果它能帮助任何人的话。

#!/usr/bin/env python3

import functools
import pyudev
import evdev
from select import select

context = pyudev.Context()
monitor = pyudev.Monitor.from_netlink(context)
monitor.filter_by(subsystem='bluetooth')
monitor.start()


fds = {monitor.fileno(): monitor}
time = 0.0

udevices = context.list_devices(subsystem='bluetooth')
link_up = False
for udevice in udevices :
    if udevice.device_type == 'link' and udevice.is_initialized :
        link_up = True
        print('yiha')

evdevices = [evdev.InputDevice(fn) for fn in evdev.list_devices()]

if len(evdevices) > 0:
    for evdevice in evdevices:
        if evdevice.name.strip() == 'AB Shutter3' and link_up:
            print('Device existing: %s' % udevice)
            fds[evdevice.fileno()] = evdevice

while True:
    r, w, x = select(fds, [], [])

    if monitor.fileno() in r:
        for udevice in iter(functools.partial(monitor.poll, 0), None):
            evdevices = [evdev.InputDevice(fn) for fn in evdev.list_devices()]
            for evdevice in evdevices:
                if evdevice.name.strip() == 'AB Shutter3':
                    if udevice.action == u'add':
                        print('Device added: %s' % udevice)
                        fds[evdevice.fileno()] = evdevice
                        break
                    if udevice.action == u'remove':
                        print('Device removed: %s' % udevice)
                        fds.pop(evdevice.fileno(),None) 
                        break

    if evdevice.fileno() in r:
        dev = fds[evdevice.fileno()]
        for event in dev.read():
            if event.type == evdev.ecodes.EV_KEY:
                data = evdev.categorize(event)
                if data.keystate == 1 and data.event.timestamp() - time > 0.05 :
                    if data.scancode == 115:
                        print("Big button")
                    elif data.scancode == 28:
                        print("Small button")
                time = data.event.timestamp()

我很确定几个月后我会惊恐地看着这一点，但就目前而言，它起到了作用。