我遇到了以下行为 . 使用了具有以下结构的代码块,
try:
tup = tuple(<some_expression> for <_> in <iterator>)
except <SomeException>:
pass
当在生成元组期间(在生成器表达式内)引发 SomeException
时, try
- except
块没有处理它,而是整个程序停止 . 为什么会这样?有没有办法确保在genexpr中遇到异常 . 是"broadcasted"到外部范围?
具体例子
test.py
:
def input_generator():
try:
while True:
for token in input().split():
yield token
except EOFError:
pass
pyIn = input_generator()
def tuple_gen(n: int):
try:
while True:
yield tuple(next(pyIn) for _ in range(n))
except StopIteration:
pass
except ValueError:
pass
if __name__ == "__main__":
for a, b in tuple_gen(2):
print(a, b)
考虑迭代 tuple_gen
生成器的实例,使用空文件作为输入(如 stdin
) . 遇到EOF时, pyIn
生成器终止,因此 next(pyIn)
引发 StopIteration
,但是程序停止,而不是被 except
块捕获 .
例如,保存一个空的 test.txt
文件(只是一个空行)并在(Windows)控制台上运行它
python test.py < test.txt
导致以下Traceback:
Traceback (most recent call last):
File "test.py", line 16, in <genexpr>
yield tuple(next(pyIn) for _ in range(n))
StopIteration
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "test.py", line 24, in <module>
for a, b in tuple_gen(2):
File "test.py", line 16, in tuple_gen
yield tuple(next(pyIn) for _ in range(n))
RuntimeError: generator raised StopIteration