Question

最近我正在尝试编写GUI脚本，该脚本将捕获来自QMC5883l数字罗盘的数据并实时在小gui中显示数据，该脚本可以正常工作，并且没有错误，除非指南针断开连接，OSError正常上升，并且程序停止，我用try-catch来解决这个问题，所以现在当异常引发它很好地表明指南针断开连接时，但是当指南针重新连接时它将不再像存储在oserror异常代码中一样工作我需要知道错误结束后是否有任何方法可以返回尝试脚本

我的代码在下面

# This Python file uses the following encoding: utf-8
import smbus            #import SMBus module of I2C
from time import sleep  #import sleep
import math
import sys
import os
from tkinter import *
#some MPU6050 Registers and their Address                         
Register_mode  = 0x09           #Address of mode register
Register_set_reset = 0x0b       #Addreas of set/reset period
X_axis_H    = 0x01              #Address of X-axis MSB data register
Z_axis_H    = 0x03              #Address of Z-axis MSB data register
Y_axis_H    = 0x05              #Address of Y-axis MSB data register
declination = 1.466          #define declination angle of location where measurement going to be done
pi          = 3.14159265359     #define pi value

def Magnetometer_Init():
        #Write to mode R`egister for selecting mode
        bus.write_byte_data(Device_Address, Register_mode, 0x1d)
        bus.write_byte_data(Device_Address, Register_set_reset , 0x01)
def read_raw_data(addr):
          #Read raw 16-bit value
        high = bus.read_byte_data(Device_Address, addr)
        low = bus.read_byte_data(Device_Address, addr-1)
        #concatenate higher and lower value
        value = ((high << 8) | low)

        #to get signed value from module
        if(value > 32768):
            value = value - 65536
        return value


bus = smbus.SMBus(1)    # or bus = smbus.SMBus(0) for older version boards
Device_Address = 0x0d   #QMC5883L magnetometer device address

Magnetometer_Init()     # initialize qMC5883L magnetometer 
print (" Reading Heading Angle")
window = Tk()
window.title("Welcome to LikeGeeks app")
window.geometry('350x200')
lbl = Label(window, text='heading angle')
lbl.grid(column=0, row=0)

def mainloop1():
        try:
        #Read Accelerometer raw value
                x = read_raw_data(X_axis_H)
                z = read_raw_data(Z_axis_H)
                y = read_raw_data(Y_axis_H)
        #Due to declination check for >360 degree
                heading = math.atan2(y, x) + declination        
                if(heading > 2*pi):
                        heading = heading - 2*pi

                #check for sign
                if(heading < 0):
                        heading = heading + 2*pi

                #convert into angle
                heading_angle = int(heading * 180/pi)
                lbl.configure(text=heading_angle)
                window.after(1,mainloop1)
          except OSError:
                  lbl.configure(text='compass disconnected')
window.after(0, mainloop1)      
window.mainloop()

Answer 1

由于window.after(1, mainloop1)在try块内被调用，一旦出现异常，它将不会被执行并且mainloop1()也不会再次执行。

要克服它，只需将window.after(1, mainloop1)从try块移到mainloop1()的末尾，如下所示：

def mainloop1():
    try:
        ...
        lbl.configure(text=heading_angle)
    except OSError as err:
        lbl.configure(text='compass disconnected')
    window.after(1, mainloop1)

然后window.after(1, mainloop1)将被执行，即使发生异常。

异常结束时如何返回尝试脚本

1 个答案: