flake8-no-implicit-concat

0.3.7 · active · verified Wed Apr 15

flake8-no-implicit-concat is a Flake8 plugin designed to forbid implicit string and bytes literal concatenations in Python code. It helps enforce a coding style where string concatenation is always explicit, thereby preventing subtle bugs caused by accidentally concatenated literals. The current version is 0.3.7, and the project maintains an active release cadence with regular updates.

Warnings

gotcha Implicit string concatenation can lead to silent and hard-to-debug errors, especially when defining lists or tuples where a missing comma can result in two intended separate string elements becoming a single concatenated string. This plugin helps prevent such issues.
Fix: Ensure all string concatenations are explicit (e.g., using `+` or `.join()`) or that separate string literals in collections are properly delimited by commas.
gotcha By default, `flake8-no-implicit-concat` only checks for implicit concatenations on the same line (NIC001). To also check for concatenations spanning multiple lines, you need to enable the `--check-str-concat-over-line-jumps=y` option.
Fix: Add `--check-str-concat-over-line-jumps=y` to your Flake8 command or configuration file (e.g., `setup.cfg`, `pyproject.toml`) to enforce checking across line jumps.
gotcha This plugin specifically *forbids* implicit string concatenation. Be aware that another popular plugin, `flake8-implicit-str-concat`, has different goals and may *encourage* implicit concatenation in certain multi-line scenarios (e.g., within parentheses for PEP 8 compliance). Choose the plugin that aligns with your desired coding style.
Fix: Review your project's coding style guide and select the appropriate plugin. If you want to strictly forbid all implicit concatenations, `flake8-no-implicit-concat` is the correct choice.

Install

pip install flake8-no-implicit-concat Install with pip

Quickstart

After installation, `flake8-no-implicit-concat` is automatically registered with Flake8. Simply run `flake8` on your project to start detecting implicit string/bytes literal concatenations. The plugin uses error codes prefixed with 'NIC' (No Implicit Concatenation).

# Install the plugin
pip install flake8-no-implicit-concat

# Create a Python file with implicit concatenation (e.g., example.py)
# print('hello' 'world')

# Run flake8 to detect the issue
flake8 example.py

# Output will include a 'NIC' error, e.g.:
# example.py:1:7: NIC001 Implicit string literal concatenation.

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