Add linter setup copied from torchtune (pytorch#34)

note that you should install the pre-commit tool from
`dev-requirements.txt` and then you can invoke `pre-commit` from the CLI
to get the same linters/formatters applied locally as would be run under
CI.

.flake8

@@ -0,0 +1,27 @@
+[flake8]
+# Suggested config from pytorch that we can adapt
+select = B,C,E,F,N,P,T4,W,B9,TOR0,TOR1,TOR2
+max-line-length = 120
+# C408 ignored because we like the dict keyword argument syntax
+# E501 is not flexible enough, we're using B950 instead
+# N812 ignored because import torch.nn.functional as F is PyTorch convention
+# N817 ignored because importing using acronyms is convention (DistributedDataParallel as DDP)
+# E731 allow usage of assigning lambda expressions
+ignore =
+    E203,E305,E402,E501,E721,E741,F405,F821,F841,F999,W503,W504,C408,E302,W291,E303,N812,N817,E731
+    # shebang has extra meaning in fbcode lints, so I think it's not worth trying
+    # to line this up with executable bit
+    EXE001,
+    # these ignores are from flake8-bugbear; please fix!
+    B007,B008,
+optional-ascii-coding = True
+exclude =
+    ./.git,
+    ./docs
+    ./build
+    ./scripts,
+    ./venv,
+    *.pyi
+    .pre-commit-config.yaml
+    *.md
+    .flake8

.github/workflows/lint.yaml

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+name: Lint
+
+on:
+  pull_request:
+
+concurrency:
+  group: lint-${{ github.workflow }}-${{ github.ref == 'refs/heads/main' && github.run_number || github.ref }}
+  cancel-in-progress: true
+
+defaults:
+  run:
+    shell: bash -l -eo pipefail {0}
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ['3.11']
+    steps:
+      - name: Check out repo
+        uses: actions/checkout@v3
+      - name: Setup python
+        uses: actions/setup-python@v4
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Update pip
+        run: python -m pip install --upgrade pip
+      - name: Install lint utilities
+        run: |
+          python -m pip install pre-commit
+          pre-commit install-hooks
+      - id: file_changes
+        uses: trilom/[email protected]
+        with:
+          prNumber: ${{ github.event.number }}
+          output: ' '
+      - name: Lint modified files
+        run: pre-commit run --files ${{ steps.file_changes.outputs.files }}

.pre-commit-config.yaml

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+exclude: 'build'
+
+default_language_version:
+    python: python3
+
+repos:
+-   repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: 6306a48f7dae5861702d573c9c247e4e9498e867
+    hooks:
+    -   id: trailing-whitespace
+    -   id: check-ast
+    -   id: check-merge-conflict
+    -   id: no-commit-to-branch
+        args: ['--branch=main']
+    -   id: check-added-large-files
+        args: ['--maxkb=500']
+    -   id: end-of-file-fixer
+        exclude: '^(.*\.svg)$'
+
+-   repo: https://github.com/Lucas-C/pre-commit-hooks
+    rev: v1.5.4
+    hooks:
+    -   id: insert-license
+        files: \.py$
+        args:
+        - --license-filepath
+        - docs/license_header.txt
+
+-   repo: https://github.com/pycqa/flake8
+    rev: 34cbf8ef3950f43d09b85e2e45c15ae5717dc37b
+    hooks:
+    -   id: flake8
+        additional_dependencies:
+          - flake8-bugbear == 22.4.25
+          - pep8-naming == 0.12.1
+          - torchfix
+        args: ['--config=.flake8']
+
+-   repo: https://github.com/omnilib/ufmt
+    rev: v2.3.0
+    hooks:
+    -   id: ufmt
+        additional_dependencies:
+          - black == 22.12.0
+          - usort == 1.0.5
+
+- repo: https://github.com/jsh9/pydoclint
+  rev: d88180a8632bb1602a4d81344085cf320f288c5a
+  hooks:
+    - id: pydoclint
+      args: [--config=pyproject.toml]

dev-requirements.txt

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+pytest
+pytest-cov
+pre-commit

pyproject.toml

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+[tool.pydoclint]
+style = 'google'
+check-return-types = 'False'
+
+[tool.pytest.ini_options]
+addopts = ["--showlocals"] # show local variables in tracebacks