format不生效？

python代码如下：

msg = """过去24小时Android稳定性测试运行数据汇总如下：
执行成功次数：{count}
执行成功率：{percent}%
总运行时长：{run_time}
覆盖包体个数：{package_num}
页面最高覆盖率：{coverage}%
覆盖的系统版本：Android {os}
覆盖的设备厂商：{brand}
覆盖的设备数：{device_num}
"""
count = coverage = run_time = 0
os = []
brand = []
crash_title = []
packages = []
devices = []
...
msg.format(count=count, percent=percent, run_time=run_time, package_num=len(packages),
           coverage=coverage, os=",".join(os), brand=",".join(brand), device_num=len(devices))
print(msg)

这段代码有没有问题？可以试着运行一下看看效果~

你会发现msg值没有更新成功？

有经验的朋友可能一下就看出来问题在哪里了

format之后需要重新赋值呀！！！改成如下形式就可以了。。

msg = msg.format(count=count, percent=percent, run_time=run_time, package_num=len(packages),
                     coverage=coverage, os=",".join(os), brand=",".join(brand), device_num=len(devices))