Contextlib2: Enhanced Context Management

21.6.0 · maintenance · verified Thu Apr 09

Contextlib2 provides backports and enhancements for Python's standard `contextlib` module, offering features like `ExitStack` and `asynccontextmanager` to older Python versions. The current version is 21.6.0, released in June 2021. The project appears to be in maintenance mode, as most of its key features are now integrated into the standard library for Python versions 3.7 and newer.

Warnings

gotcha For Python 3.7 and newer, `contextlib2` is largely superseded. Most features it backports are available directly in the standard `contextlib` module. Importing from `contextlib2` in modern Python versions unnecessarily adds a dependency and might cause confusion.
Fix: Prefer `from contextlib import ...` for `ExitStack`, `suppress`, `asynccontextmanager`, etc., in Python 3.7+ projects. Only use `contextlib2` if targeting older Python versions or very specific, documented enhancements.
deprecated The project has seen minimal updates since its last release in June 2021. This indicates it is in a maintenance-only state, with no new features planned and potentially slow resolution for future bugs or security issues.
Fix: Evaluate if the dependency is strictly necessary. If a feature is available in the standard library, prioritize that. Consider the long-term maintenance risk for new projects.
gotcha Despite `contextlib2` requiring Python >=3.6, its primary utility was backporting features to significantly older Python versions (like 2.7 or early Python 3.x). For Python 3.6+, many of its features are already native, making its use redundant in many cases.
Fix: Carefully review which specific features you intend to use. If they are already in the standard `contextlib` for your target Python 3.6+ version, remove the `contextlib2` dependency.

Install

pip install contextlib2 Install `contextlib2`

Imports

ExitStack
```
from contextlib2 import ExitStack
```
While `ExitStack` is in `contextlib` from Python 3.3+, importing from `contextlib2` might be done for consistency in mixed-version environments or for older Python 3 versions where `contextlib2` provided fixes/enhancements.
contextmanager
```
from contextlib2 import contextmanager
```
`contextmanager` is standard, but `contextlib2` could be used for very old Python 3 versions or specific backport needs.
suppress
```
from contextlib2 import suppress
```
`suppress` is in standard `contextlib` from Python 3.4+. Use `contextlib2` only if targeting Python <3.4 or specific behavior.
redirect_stdout
```
from contextlib2 import redirect_stdout
```
`redirect_stdout` is in standard `contextlib` from Python 3.4+. Use `contextlib2` only if targeting Python <3.4 or specific behavior.
asynccontextmanager
```
from contextlib2 import asynccontextmanager
```
`asynccontextmanager` is in standard `contextlib` from Python 3.7+. If targeting Python <3.7, `contextlib2` was a backport solution. For Python 3.7+, use the standard library.

Quickstart

This example demonstrates `ExitStack` to manage multiple context managers dynamically. It opens several files and ensures they are all properly closed upon exiting the `with` block, even if errors occur.

from contextlib2 import ExitStack
import os

def open_files(filenames):
    with ExitStack() as stack:
        files = [stack.enter_context(open(fname, 'r')) for fname in filenames]
        yield files

# Example usage (will create dummy files first)
if __name__ == '__main__':
    # Create dummy files
    with open('file1.txt', 'w') as f: f.write('Hello from file 1')
    with open('file2.txt', 'w') as f: f.write('Hello from file 2')

    try:
        with open_files(['file1.txt', 'file2.txt']) as opened:
            for i, f in enumerate(opened):
                print(f"Content of file {i+1}: {f.read()}")
    finally:
        os.remove('file1.txt')
        os.remove('file2.txt')

view raw JSON →