X-Git-Url: https://git.madduck.net/etc/vim.git/blobdiff_plain/4501f22fcbd711b56f5d63eda8d583afab24a1c6..b0f3798aab36ff4ee20ae68b1b4cd73acd5fc54c:/README.md diff --git a/README.md b/README.md index 79e57aa..8f539e2 100644 --- a/README.md +++ b/README.md @@ -33,9 +33,10 @@ Try it out now using the [Black Playground](https://black.now.sh). Watch the _Contents:_ **[Installation and usage](#installation-and-usage)** | **[Code style](#the-black-code-style)** | **[Pragmatism](#pragmatism)** | **[pyproject.toml](#pyprojecttoml)** | **[Editor integration](#editor-integration)** | -**[blackd](#blackd)** | **[Version control integration](#version-control-integration)** -| **[Ignoring unmodified files](#ignoring-unmodified-files)** | **[Used by](#used-by)** -| **[Testimonials](#testimonials)** | **[Show your style](#show-your-style)** | +**[blackd](#blackd)** | **[black-primer](#black-primer)** | +**[Version control integration](#version-control-integration)** | +**[Ignoring unmodified files](#ignoring-unmodified-files)** | **[Used by](#used-by)** | +**[Testimonials](#testimonials)** | **[Show your style](#show-your-style)** | **[Contributing](#contributing-to-black)** | **[Change Log](#change-log)** | **[Authors](#authors)** @@ -52,7 +53,7 @@ run but you can reformat Python 2 code with it, too. To get started right away with sensible defaults: -``` +```sh black {source_file_or_directory} ``` @@ -150,6 +151,50 @@ should be configured to neither warn about nor overwrite _Black_'s changes. Actual details on _Black_ compatible configurations for various tools can be found in [compatible_configs](https://github.com/psf/black/blob/master/docs/compatible_configs.md). +### Migrating your code style without ruining git blame + +A long-standing argument against moving to automated code formatters like _Black_ is +that the migration will clutter up the output of `git blame`. This was a valid argument, +but since Git version 2.23, Git natively supports +[ignoring revisions in blame](https://git-scm.com/docs/git-blame#Documentation/git-blame.txt---ignore-revltrevgt) +with the `--ignore-rev` option. You can also pass a file listing the revisions to ignore +using the `--ignore-revs-file` option. The changes made by the revision will be ignored +when assigning blame. Lines modified by an ignored revision will be blamed on the +previous revision that modified those lines. + +So when migrating your project's code style to _Black_, reformat everything and commit +the changes (preferably in one massive commit). Then put the full 40 characters commit +identifier(s) into a file. + +``` +# Migrate code style to Black +5b4ab991dede475d393e9d69ec388fd6bd949699 +``` + +Afterwards, you can pass that file to `git blame` and see clean and meaningful blame +information. + +```console +$ git blame important.py --ignore-revs-file .git-blame-ignore-revs +7a1ae265 (John Smith 2019-04-15 15:55:13 -0400 1) def very_important_function(text, file): +abdfd8b0 (Alice Doe 2019-09-23 11:39:32 -0400 2) text = text.lstrip() +7a1ae265 (John Smith 2019-04-15 15:55:13 -0400 3) with open(file, "r+") as f: +7a1ae265 (John Smith 2019-04-15 15:55:13 -0400 4) f.write(formatted) +``` + +You can even configure `git` to automatically ignore revisions listed in a file on every +call to `git blame`. + +```console +$ git config blame.ignoreRevsFile .git-blame-ignore-revs +``` + +**The one caveat is that GitHub and GitLab do not yet support ignoring revisions using +their native UI of blame.** So blame information will be cluttered with a reformatting +commit on those platforms. (If you'd like this feature, there's an open issue for +[GitLab](https://gitlab.com/gitlab-org/gitlab/-/issues/31423) and please let GitHub +know!) + ### NOTE: This is a beta product _Black_ is already [successfully used](#used-by) by many projects, small and big. It @@ -238,6 +283,69 @@ def very_important_function( ... ``` +_Black_ prefers parentheses over backslashes, and will remove backslashes if found. + +```py3 +# in: + +if some_short_rule1 \ + and some_short_rule2: + ... + +# out: + +if some_short_rule1 and some_short_rule2: + ... + + +# in: + +if some_long_rule1 \ + and some_long_rule2: + ... + +# out: + +if ( + some_long_rule1 + and some_long_rule2 +): + ... + +``` + +Backslashes and multiline strings are one of the two places in the Python grammar that +break significant indentation. You never need backslashes, they are used to force the +grammar to accept breaks that would otherwise be parse errors. That makes them confusing +to look at and brittle to modify. This is why _Black_ always gets rid of them. + +If you're reaching for backslashes, that's a clear signal that you can do better if you +slightly refactor your code. I hope some of the examples above show you that there are +many ways in which you can do it. + +However there is one exception: `with` statements using multiple context managers. +Python's grammar does not allow organizing parentheses around the series of context +managers. + +We don't want formatting like: + +```py3 +with make_context_manager1() as cm1, make_context_manager2() as cm2, make_context_manager3() as cm3, make_context_manager4() as cm4: + ... # nothing to split on - line too long +``` + +So _Black_ will now format it like this: + +```py3 +with \ + make_context_manager(1) as cm1, \ + make_context_manager(2) as cm2, \ + make_context_manager(3) as cm3, \ + make_context_manager(4) as cm4 \ +: + ... # backslashes and an ugly stranded colon +``` + You might have noticed that closing brackets are always dedented and that a trailing comma is always added. Such formatting produces smaller diffs; when you add or remove an element, it's always just one line. Also, having the closing bracket dedented provides a @@ -418,9 +526,12 @@ PEP 8 [recommends](https://www.python.org/dev/peps/pep-0008/#whitespace-in-expressions-and-statements) to treat `:` in slices as a binary operator with the lowest priority, and to leave an equal amount of space on either side, except if a parameter is omitted (e.g. -`ham[1 + 1 :]`). It also states that for extended slices, both `:` operators have to -have the same amount of spacing, except if a parameter is omitted (`ham[1 + 1 ::]`). -_Black_ enforces these rules consistently. +`ham[1 + 1 :]`). It recommends no spaces around `:` operators for "simple expressions" +(`ham[lower:upper]`), and extra space for "complex expressions" +(`ham[lower : upper + offset]`). _Black_ treats anything more than variable names as +"complex" (`ham[lower : upper + 1]`). It also states that for extended slices, both `:` +operators have to have the same amount of spacing, except if a parameter is omitted +(`ham[1 + 1 ::]`). _Black_ enforces these rules consistently. This behaviour may raise `E203 whitespace before ':'` warnings in style guide enforcement tools like Flake8. Since `E203` is not PEP 8 compliant, you should tell @@ -958,7 +1069,7 @@ Options: There is no official blackd client tool (yet!). You can test that blackd is working using `curl`: -``` +```sh blackd --bind-port 9090 & # or let blackd choose a port curl -s -XPOST "localhost:9090" -d "print('valid')" ``` @@ -1007,6 +1118,124 @@ Apart from the above, `blackd` can produce the following response codes: The response headers include a `X-Black-Version` header containing the version of _Black_. +## black-primer + +`black-primer` is a tool built for CI (and huumans) to have _Black_ `--check` a number +of (configured in `primer.json`) Git accessible projects in parallel. _(A PR will be +accepted to add Mercurial support.)_ + +### Run flow + +- Ensure we have a `black` + `git` in PATH +- Load projects from `primer.json` +- Run projects in parallel with `--worker` workers (defaults to CPU count / 2) + - Checkout projects + - Run black and record result + - Clean up repository checkout _(can optionally be disabled via `--keep`)_ +- Display results summary to screen +- Default to cleaning up `--work-dir` (which defaults to tempfile schemantics) +- Return + - 0 for successful run + - < 0 for environment / internal error + - > 0 for each project with an error + +### Speed up Runs 🏎 + +If you're running locally yourself to test black on lots of code try: + +- Using `-k` / `--keep` + `-w` / `--work-dir` so you don't have to re-checkout the repo + each run + +### CLI Arguments + +```text +Usage: black-primer [OPTIONS] + + primer - prime projects for blackening ... 🏴 + +Options: + -c, --config PATH JSON config file path [default: /Users/cooper/repos/ + black/src/black_primer/primer.json] + + --debug Turn on debug logging [default: False] + -k, --keep Keep workdir + repos post run [default: False] + -L, --long-checkouts Pull big projects to test [default: False] + -R, --rebase Rebase project if already checked out [default: + False] + + -w, --workdir PATH Directory Path for repo checkouts [default: /var/fol + ders/tc/hbwxh76j1hn6gqjd2n2sjn4j9k1glp/T/primer.20200 + 517125229] + + -W, --workers INTEGER Number of parallel worker coroutines [default: 69] + -h, --help Show this message and exit. +``` + +### primer config file + +The config is `JSON` format. It's main element is the `"projects"` dictionary. Below +explains each parameter: + +```json +{ + "projects": { + "00_Example": { + "cli_arguments": "List of extra CLI arguments to pass Black for this project", + "expect_formatting_changes": "Boolean to indicate that the version of Black is expected to cause changes", + "git_clone_url": "URL you would pass `git clone` to check out this repo", + "long_checkout": "Boolean to have repo skipped by defauult unless `--long-checkouts` is specified", + "py_versions": "List of major Python versions to run this project with - all will do as you'd expect - run on ALL versions" + }, + "aioexabgp": { + "cli_arguments": [], + "expect_formatting_changes": true, + "git_clone_url": "https://github.com/cooperlees/aioexabgp.git", + "long_checkout": false, + "py_versions": ["all", "3.8"] // "all" ignores all other versions + } + } +} +``` + +### Example run + +```console +cooper-mbp:black cooper$ ~/venvs/b/bin/black-primer +[2020-05-17 13:06:40,830] INFO: 4 projects to run black over (lib.py:270) +[2020-05-17 13:06:44,215] INFO: Analyzing results (lib.py:285) +-- primer results 📊 -- + +3 / 4 succeeded (75.0%) ✅ +1 / 4 FAILED (25.0%) 💩 + - 0 projects Disabled by config + - 0 projects skipped due to Python Version + - 0 skipped due to long checkout + +Failed Projects: + +## flake8-bugbear: + - Returned 1 + - stdout: +--- tests/b303_b304.py 2020-05-17 20:04:09.991227 +0000 ++++ tests/b303_b304.py 2020-05-17 20:06:42.753851 +0000 +@@ -26,11 +26,11 @@ + maxint = 5 # this is okay + # the following shouldn't crash + (a, b, c) = list(range(3)) + # it's different than this + a, b, c = list(range(3)) +- a, b, c, = list(range(3)) ++ a, b, c = list(range(3)) + # and different than this + (a, b), c = list(range(3)) + a, *b, c = [1, 2, 3, 4, 5] + b[1:3] = [0, 0] + +would reformat tests/b303_b304.py +Oh no! 💥 💔 💥 +1 file would be reformatted, 22 files would be left unchanged. +``` + ## Version control integration Use [pre-commit](https://pre-commit.com/). Once you @@ -1031,7 +1260,7 @@ for your project. See _Black_'s own example. If you're already using Python 3.7, switch the `language_version` accordingly. Finally, -`stable` is a tag that is pinned to the latest release on PyPI. If you'd rather run on +`stable` is a branch that tracks the latest release on PyPI. If you'd rather run on master, this is also an option. ## Ignoring unmodified files @@ -1060,10 +1289,10 @@ then write the above files to `.cache/black//`. The following notable open-source projects trust _Black_ with enforcing a consistent code style: pytest, tox, Pyramid, Django Channels, Hypothesis, attrs, SQLAlchemy, -Poetry, PyPA applications (Warehouse, Pipenv, virtualenv), pandas, Pillow, every Datadog -Agent Integration, Home Assistant. +Poetry, PyPA applications (Warehouse, Bandersnatch, Pipenv, virtualenv), pandas, Pillow, +every Datadog Agent Integration, Home Assistant. -The following organizations use _Black_: Dropbox. +The following organizations use _Black_: Facebook, Dropbox. Are we missing anyone? Let us know.