对于with嵌套如何优化 about one-python-craftsman HOT 2 CLOSED

你好，普通的写法就是全部摊开来，比如：

with open('foo.txt') as f1, open('bar.txt') as f2:
    ...

也可以使用 contextlib.ExitStack 。文档里就有一个示例：

For example, a set of files may easily be handled in a single with statement as follows:

with ExitStack() as stack:
    files = [stack.enter_context(open(fname)) for fname in filenames]
    # All opened files will automatically be closed at the end of
    # the with statement, even if attempts to open files later
    # in the list raise an exception

Each instance maintains a stack of registered callbacks that are called in reverse order when the instance is closed (either explicitly or implicitly at the end of a with statement). Note that callbacks are not invoked implicitly when the context stack instance is garbage collected.

from one-python-craftsman.

谢谢作者。

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