为什么无法通过try-except处理"io.UnsupportedOperation“错误

Question

运行以下代码将引发io.UnsupportedOperation错误，因为该文件是以“写入”模式打开的-

with open("hi.txt", "w") as f:
    print(f.read())

输出为-

io.UnsupportedOperation: not readable

所以，我们可以通过这样做来掩盖这一点-

try:
    with open("hi.txt", "w") as f:
        print(f.read())
except io.UnsupportedOperation:
    print("Please give the file read permission")

输出-

NameError: name 'io' is not defined

甚至去掉了“io”吐出了同样的错误-

try:
    with open("hi.txt", "w") as f:
        print(f.read())
except UnsupportedOperation:
    print("Please give the file read permission")

输出-

NameError: name 'UnsupportedOperation' is not defined

为什么它不起作用？"io.UnsupportedOperation“不是一个错误吗？

Answer 1

可以在模块io中找到io.UnsupportedError。因此，在使用它之前，我们需要导入io。

import io

然后，当我们测试try except子句中的错误时，我们可以使用io.UnsupportedError。这为我们提供了：

import io

try:
    with open("hi.txt", "w") as f:
        print(f.read())
except io.UnsupportedOperation as e:
    print(e)

或者如果你只使用io模块来检查这个特定的错误。

from io import UnsupportedError

try:
    with open("hi.txt", "w") as f:
        print(f.read())
except UnsupportedOperation as e:
    print(e)