Python can substitute an empty context manager without conditions inside!

It often happens that a resource needs to be opened via with, and sometimes the object is already ready and there's no need to open anything.

This usually leads to code duplication or conditions around with:

if need_open:
    f = open(...)
else:
    f = existing_file

`nullcontext(obj) behaves like an empty context manager and allows you to maintain a single execution flow.

This is especially useful for APIs, tests, optional resources, dependency injection, and functions that can accept both a path and a ready-made object.


with ctx as resource:
    process(resource)

But note that nullcontext() does not close the passed object — it simply passes it on further.

🔥 nullcontext() helps to unify scenarios with optional context managers and significantly simplifies the architecture of IO code.

#Python #ContextManager #CodingTips #DevLife #Programming #Tech

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How to create your own context manager in Python for opening and closing a connection to the SQLite database

The enter() method is used when opening a connection, and the exit() method is used when closing it:

import sqlite3

class DatabaseConnection:
    def __init__(self, db_name):
        self.db_name = db_name
        self.connection = None

    def __enter__(self):
        self.connection = sqlite3.connect(self.db_name)
        return self.connection

    def __exit__(self, exc_type, exc_val, exc_tb):
        if self.connection:
            self.connection.close()

# Usage
with DatabaseConnection("example.db") as conn:
    cursor = conn.cursor()
    cursor.execute("SELECT * FROM users")

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#Python #SQLite #ContextManager #Programming #Coding #Tech