Is python with block self closing opened resource?

Question

I'm a quite experimented Java developer and I am wondering wether the with block in python is acting the same as a Java embedded try/catch. In the following examples, I'm writing to a random file in python and Java

import io

with io.open("filename", "w") as file:
   file.write("a test")
   #is file.close() necessary here ?
   #file.close()

File file = new File("test.txt");
try(FileWriter writer = new FileWriter(file)) {
    writer.write("a test");
    // here writer.close() is useless as it is auto closed by the try catch block
} catch(IOException e){
    e.printStackTrace();
}

are those 2 block acting exactly the same, or is the python block not closing the resource until program ends ?

Answer 1

(open is a builtin, so you don't need to import io, io.open is simply an alias for open.)

Using your example behaves as if you did:

file = open('filename', 'w')
try:
    file.write("a test")
finally:
    file.close()

So this means the file is closed automatically, both on success or if an exception is raised.

For more information on the with statement, I recommend the Python documentation:

• The with statement
• With Statement Context Managers
• contextlib

Context managers are really useful and versatile tools, I recommend reading more about them!