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Pyflakes checks Python source for selected errors without importing or running the modules it examines. That makes it a focused option for finding certain source-level problems while avoiding module initialization side effects; it is not a style checker or a full code-analysis suite.
What does Pyflakes check?
Pyflakes parses each Python file and inspects its syntax tree for selected errors. The project deliberately keeps that scope limited: it analyzes files individually rather than trying to perform every kind of analysis across an entire application. See the Pyflakes project README for its description of this design.
The README describes its aim this way: “Pyflakes makes a simple promise: it will never complain about style, and it will try very, very hard to never emit false positives.” This is the project’s stated design goal, not a guarantee that every possible issue will be found or that false positives are impossible.
Does Pyflakes run Python code?
No. Pyflakes says it parses source code rather than importing a module. It therefore does not execute a file’s module-level initialization code merely to inspect it. This is why the project describes Pyflakes as safe to use on modules with side effects, such as code that might perform actions during import.
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Pyflakes also says its narrow, file-by-file syntax-tree approach makes it faster than Pylint. That is the project’s explanation; the official sources cited here do not provide current comparative benchmark figures.
How do you install and run Pyflakes?
The project README documents installation with pip and invocation as a Python module. Using the same interpreter for installation and checking helps avoid installing Pyflakes into one Python environment and running another.
- Install for the default Python interpreter:
python -m pip install --upgrade pyflakes - Check the current directory:
python -m pyflakes . - To target a specific interpreter, replace
pythonin both commands with its command name, such aspython3.11:python3.11 -m pip install pyflakes, thenpython3.11 -m pyflakes ..
The project setup metadata also exposes a pyflakes console command. The module form makes the interpreter choice explicit.
How is Pyflakes different from Flake8?
Pyflakes focuses on selected source-level errors and does not report style. The project README suggests Flake8 for readers who want stylistic checks and per-project configuration; it describes Flake8 as combining Pyflakes with style checks against PEP 8 and adding configuration options. The README puts it plainly: “If you require more options and more flexibility, you could give a look to Flake8 too.”
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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstall| Question | Pyflakes | Flake8, as described by the Pyflakes README |
|---|---|---|
| Primary scope | Selected errors found by inspecting each file’s syntax tree | Pyflakes plus style checks against PEP 8 |
| Style diagnostics | Not intended to report style | Includes style checks |
| Per-project configuration | Not identified as a feature in the cited README | Identified by the README as an advantage |
| Execution model | Parses source without importing modules | Not stated in the cited Pyflakes README |
Choose based on what you need checked: Pyflakes suits a narrow, non-executing source check; Flake8 is the project’s suggested direction when style diagnostics and per-project configuration matter. Neither description establishes a universal winner.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Which Python versions does Pyflakes 4.0.0 support?
PyPI lists Pyflakes 4.0.0 as released on September 22, 2026, and its package metadata says Requires Python >=3.10. The same PyPI page’s embedded project description says active Python versions 3.9+. Those statements conflict, so use the package requirement for the specific release you install and verify the metadata for that version. See Pyflakes 4.0.0 on PyPI.
The project’s changelog records Pyflakes 3.4.0 on June 20, 2025, including Python 3.14 support. That older release note does not supersede the newer 4.0.0 package metadata. The changelog is available at Pyflakes NEWS.rst.
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