为什么不能通过 try-except 处理“io.UnsupportedOperation”错误

Question

运行以下代码将引发 io.UnsupportedOperation 错误，因为文件以“写入”模式打开 -

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

输出是 -

io.UnsupportedOperation: not readable

所以，我们可以尝试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

甚至删除“io”。吐出同样的错误 -

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”不是错误吗？

Answer 1

io.UnsupportedError 可在模块 io 中找到。因此，在使用之前，我们需要导入io

import io

那么当我们测试 try except 子句中的错误时，我们可以使用 io.UnsupportedError。这给了我们：

import io

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

或者如果您仅使用 io 模块来检查此特定错误。

from io import UnsupportedError

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