python with

三个代码等价。with还可以很好的处理上下文环境产生的异常。

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file = open("/tmp/foo.txt") data = file.read() file.close()

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file = open("/tmp/foo.txt") try:     data = file.read() finally:     file.close()

1 2	with open("/tmp/foo.txt") as file:     data = file.read()