Python notes - with as statement

with as The main functions of the statement are as follows ：

The first is to solve the problem of resource release during abnormal exit ;

The second is to solve the problem that users forget to call close Resource leakage caused by method .

There are some tasks , It may need to be set up beforehand , Clean up afterwards . For this scenario ,Python Of with Statements provide a very convenient way to do this . A good example is file processing , You need to get a file handle , Reading data from a file , Then close the file handle .

If not with sentence , The code is as follows ：

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

Here are two questions . One is that you may forget to close the file handle ; Second, the file read data is abnormal , There was no treatment . Here is an enhanced version of handling exceptions ：

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