Creating new context manager in Python

What is Context Manager?

chanduthedev

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Sep 13, 2024

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• Context manager is a easy way to maintain resources.
• It will be used along with with keyword
• It will automatically handles cleaning up resources after used.
• One of the best example for context manager is file open given below.
• We no need to close the file, context manager will take care of closing the file.

with open("sample.txt", "r") as f_obj:
    for line in f_obj:
        print(line.strip())

Internal Working of a Context Manager

• A context manager is a construct used to manage resources like files, network connections, and locks. The context manager protocol relies on two special methods __enter_ and __exit__
• When using a context manager, the with statement essentially does the following:

1. Calling __enter__() method
   - When with statement entered, this method will be called
   - All the resource initialization will happen
   - New object will be returned which will be assinged to as clause
2. Executing the block of code after with statement
   - The code inside with will be executed
   - If any error/exception, it will call __exit__ method
3. Calling __exit__() method to make clean up process
   - This method will call after completing step 2 or any error in step 2
   - This method will clean up(e.g. closing file) all the…