update pre-commit hooks

Author: efajardo-nv

.pre-commit-config.yaml

@@ -1,16 +1,17 @@
 repos:
+  - repo: https://github.com/timothycrosley/isort
+    rev: 5.0.7
+    hooks:
+          - id: isort
   - repo: https://github.com/ambv/black
-    rev: stable
+    rev: 19.10b0
     hooks:
     - id: black
-      language_version: python3.7
-  - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v2.2.3
-    hooks:
-    -   id: trailing-whitespace
-        language_version: python3.7
-  - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v2.2.3
+  - repo: https://gitlab.com/pycqa/flake8
+    rev: 3.8.3
     hooks:
-    -   id: debug-statements
-        language_version: python3.7
+          - id: flake8
+            alias: flake8
+            name: flake8
+            args: ["--config=python/.flake8"]
+            types: [python]

CONTRIBUTING.md

@@ -51,6 +51,66 @@ implementation of the issue, ask them in the issue instead of the PR.
 
 ## Setting Up Your Build Environment
 
+### Code Formatting
+
+#### Python
+
+CLX uses [Black](https://black.readthedocs.io/en/stable/),
+[isort](https://readthedocs.org/projects/isort/), and
+[flake8](http://flake8.pycqa.org/en/latest/) to ensure a consistent code format
+throughout the project. `Black`, `isort`, and `flake8` can be installed with
+`conda` or `pip`:
+
+```bash
+conda install black isort flake8
+```
+
+```bash
+pip install black isort flake8
+```
+
+These tools are used to auto-format the Python code, as well as check the Cython
+code in the repository. Additionally, there is a CI check in place to enforce
+that committed code follows our standards. You can use the tools to
+automatically format your python code by running:
+
+```bash
+isort --atomic python/**/*.py
+black python
+```
+
+and then check the syntax of your Python code by running:
+
+```bash
+flake8 python
+```
+
+Additionally, many editors have plugins that will apply `isort` and `Black` as
+you edit files, as well as use `flake8` to report any style / syntax issues.
+
+#### Pre-commit hooks
+
+Optionally, you may wish to setup [pre-commit hooks](https://pre-commit.com/)
+to automatically run `isort`, `Black`, and `flake8` when you make a git commit.
+This can be done by installing `pre-commit` via `conda` or `pip`:
+
+```bash
+conda install -c conda-forge pre_commit
+```
+
+```bash
+pip install pre-commit
+```
+
+and then running:
+
+```bash
+pre-commit install
+```
+
+from the root of the CLX repository. Now `isort`, `Black`, and `flake8` will be
+run each time you commit changes.
+
 ### Build from Source
 
 The following instructions are for developers and contributors to CLX OSS development. These instructions are tested on Linux Ubuntu 16.04 & 18.04. Use these instructions to build CLX from source and contribute to its development.  Other operating systems may be compatible, but are not currently tested.

python/.flake8

@@ -0,0 +1,13 @@
+# Copyright (c) 2020, NVIDIA CORPORATION.
+
+[flake8]
+exclude = factory.py,perfect_hash.py
+ignore =
+    # line break before binary operator
+    W503
+    # whitespace before :
+    E203
+    # line too long (82 > 79 characters)
+    E501
+    # invalid escape sequence ‘x’
+    W605