X-Git-Url: https://git.madduck.net/etc/vim.git/blobdiff_plain/4b8823e5633b22d13650cad6e06b0330ce9985fc..41368138bbc69fd805dfc931f165e9488fc9986c:/README.md?ds=inline diff --git a/README.md b/README.md index 8aa0d06..244f60d 100644 --- a/README.md +++ b/README.md @@ -3,10 +3,11 @@

Build Status -Documentation Status +Documentation Status Coverage Status -License: MIT -PyPI +License: MIT +PyPI +Downloads Code style: black

@@ -14,7 +15,7 @@ *Black* is the uncompromising Python code formatter. By using it, you -agree to cease control over minutiae of hand-formatting. In return, +agree to cede control over minutiae of hand-formatting. In return, *Black* gives you speed, determinism, and freedom from `pycodestyle` nagging about formatting. You will save time and mental energy for more important matters. @@ -26,46 +27,87 @@ content instead. *Black* makes code review faster by producing the smallest diffs possible. +Try it out now using the [Black Playground](https://black.now.sh). -## NOTE: This is an early pre-release +--- -*Black* can already successfully format itself and the standard library. -It also sports a decent test suite. However, it is still very new. -Things will probably be wonky for a while. This is made explicit by the -"Alpha" trove classifier, as well as by the "a" in the version number. -What this means for you is that **until the formatter becomes stable, -you should expect some formatting to change in the future**. +*Contents:* **[Installation and usage](#installation-and-usage)** | +**[Code style](#the-black-code-style)** | +**[pyproject.toml](#pyprojecttoml)** | +**[Editor integration](#editor-integration)** | +**[blackd](#blackd)** | +**[Version control integration](#version-control-integration)** | +**[Ignoring unmodified files](#ignoring-unmodified-files)** | +**[Testimonials](#testimonials)** | +**[Show your style](#show-your-style)** | +**[Contributing](#contributing-to-black)** | +**[Change Log](#change-log)** | +**[Authors](#authors)** -Also, as a temporary safety measure, *Black* will check that the -reformatted code still produces a valid AST that is equivalent to the -original. This slows it down. If you're feeling confident, use -``--fast``. +--- +## Installation and usage -## Installation +### Installation *Black* can be installed by running `pip install black`. It requires Python 3.6.0+ to run but you can reformat Python 2 code with it, too. -*Black* is able to parse all of the new syntax supported on Python 3.6 -but also *effectively all* the Python 2 syntax at the same time. -## Usage +### Usage +To get started right away with sensible defaults: ``` +black {source_file_or_directory} +``` + +### Command line options + +*Black* doesn't provide many options. You can list them by running +`black --help`: + +```text black [OPTIONS] [SRC]... Options: -l, --line-length INTEGER Where to wrap around. [default: 88] - --check Don't write back the files, just return the + --py36 Allow using Python 3.6-only syntax on all input + files. This will put trailing commas in function + signatures and calls also after *args and + **kwargs. [default: per-file auto-detection] + --pyi Format all input files like typing stubs + regardless of file extension (useful when piping + source on standard input). + -S, --skip-string-normalization + Don't normalize string quotes or prefixes. + --check Don't write the files back, just return the status. Return code 0 means nothing would change. Return code 1 means some files would be reformatted. Return code 123 means there was an internal error. + --diff Don't write the files back, just output a diff + for each file on stdout. --fast / --safe If --fast given, skip temporary sanity checks. [default: --safe] + --include TEXT A regular expression that matches files and + directories that should be included on + recursive searches. On Windows, use forward + slashes for directories. [default: \.pyi?$] + --exclude TEXT A regular expression that matches files and + directories that should be excluded on + recursive searches. On Windows, use forward + slashes for directories. [default: + build/|buck-out/|dist/|_build/|\.git/|\.hg/| + \.mypy_cache/|\.tox/|\.venv/] + -q, --quiet Don't emit non-error messages to stderr. Errors + are still emitted, silence those with + 2>/dev/null. + -v, --verbose Also emit messages to stderr about files + that were not changed or were ignored due to + --exclude=. --version Show the version and exit. + --config PATH Read configuration from PATH. --help Show this message and exit. ``` @@ -74,11 +116,28 @@ Options: * it will read from standard input and write to standard output if `-` is used as the filename; * it only outputs messages to users on standard error; -* exits with code 0 unless an internal error occured (or `--check` was +* exits with code 0 unless an internal error occurred (or `--check` was used). -## The philosophy behind *Black* +### NOTE: This is a beta product + +*Black* is already successfully used by several projects, small and big. +It also sports a decent test suite. However, it is still very new. +Things will probably be wonky for a while. This is made explicit by the +"Beta" trove classifier, as well as by the "b" in the version number. +What this means for you is that **until the formatter becomes stable, +you should expect some formatting to change in the future**. That being +said, no drastic stylistic changes are planned, mostly responses to bug +reports. + +Also, as a temporary safety measure, *Black* will check that the +reformatted code still produces a valid AST that is equivalent to the +original. This slows it down. If you're feeling confident, use +``--fast``. + + +## The *Black* code style *Black* reformats entire files in place. It is not configurable. It doesn't take previous formatting into account. It doesn't reformat @@ -87,12 +146,13 @@ recognizes [YAPF](https://github.com/google/yapf)'s block comments to the same effect, as a courtesy for straddling code. -### How *Black* formats files +### How *Black* wraps lines *Black* ignores previous formatting and applies uniform horizontal and vertical whitespace to your code. The rules for horizontal -whitespace are pretty obvious and can be summarized as: do whatever -makes `pycodestyle` happy. +whitespace can be summarized as: do whatever makes `pycodestyle` happy. +The coding style used by *Black* can be viewed as a strict subset of +PEP 8. As for vertical whitespace, *Black* tries to render one full expression or simple statement per line. If this fits the allotted line length, @@ -115,13 +175,13 @@ brackets and put that in a separate indented line. ```py3 # in: -l = [[n for n in list_bosses()], [n for n in list_employees()]] +TracebackException.from_exception(exc, limit, lookup_lines, capture_locals) # out: -l = [ - [n for n in list_bosses()], [n for n in list_employees()] -] +TracebackException.from_exception( + exc, limit, lookup_lines, capture_locals +) ``` If that still doesn't fit the bill, it will decompose the internal @@ -148,7 +208,7 @@ def very_important_function( debug: bool = False, ): """Applies `variables` to the `template` and writes to `file`.""" - with open(file, 'w') as f: + with open(file, "w") as f: ... ``` @@ -160,20 +220,30 @@ between two distinct sections of the code that otherwise share the same indentation level (like the arguments list and the docstring in the example above). -Unnecessary trailing commas are removed if an expression fits in one -line. This makes it 1% more likely that your line won't exceed the -allotted line length limit. +If a data structure literal (tuple, list, set, dict) or a line of "from" +imports cannot fit in the allotted length, it's always split into one +element per line. This minimizes diffs as well as enables readers of +code to find which commit introduced a particular entry. This also +makes *Black* compatible with [isort](https://pypi.org/p/isort/) with +the following configuration. -*Black* avoids spurious vertical whitespace. This is in the spirit of -PEP 8 which says that in-function vertical whitespace should only be -used sparingly. One exception is control flow statements: *Black* will -always emit an extra empty line after ``return``, ``raise``, ``break``, -``continue``, and ``yield``. This is to make changes in control flow -more prominent to readers of your code. +
+A compatible `.isort.cfg` -That's it. The rest of the whitespace formatting rules follow PEP 8 and -are designed to keep `pycodestyle` quiet. +``` +[settings] +multi_line_output=3 +include_trailing_comma=True +force_grid_wrap=0 +combine_as_imports=True +line_length=88 +``` +The equivalent command line is: +``` +$ isort --multi-line=3 --trailing-comma --force-grid-wrap=0 --combine-as --line-width=88 [ file.py ] +``` +
### Line length @@ -214,44 +284,587 @@ bother you if you overdo it by a few km/h". ### Empty lines -*Black* will allow single empty lines left by the original editors, -except when they're added within parenthesized expressions. Since such -expressions are always reformatted to fit minimal space, this whitespace -is lost. +*Black* avoids spurious vertical whitespace. This is in the spirit of +PEP 8 which says that in-function vertical whitespace should only be +used sparingly. + +*Black* will allow single empty lines inside functions, and single and +double empty lines on module level left by the original editors, except +when they're within parenthesized expressions. Since such expressions +are always reformatted to fit minimal space, this whitespace is lost. It will also insert proper spacing before and after function definitions. It's one line before and after inner functions and two lines before and -after module-level functions. *Black* will put those empty lines also -between the function definition and any standalone comments that -immediately precede the given function. If you want to comment on the -entire function, use a docstring or put a leading comment in the function -body. +after module-level functions and classes. *Black* will not put empty +lines between function/class definitions and standalone comments that +immediately precede the given function/class. + +*Black* will enforce single empty lines between a class-level docstring +and the first following field or method. This conforms to +[PEP 257](https://www.python.org/dev/peps/pep-0257/#multi-line-docstrings). + +*Black* won't insert empty lines after function docstrings unless that +empty line is required due to an inner function starting immediately +after. + + +### Trailing commas + +*Black* will add trailing commas to expressions that are split +by comma where each element is on its own line. This includes function +signatures. + +Unnecessary trailing commas are removed if an expression fits in one +line. This makes it 1% more likely that your line won't exceed the +allotted line length limit. Moreover, in this scenario, if you added +another argument to your call, you'd probably fit it in the same line +anyway. That doesn't make diffs any larger. + +One exception to removing trailing commas is tuple expressions with +just one element. In this case *Black* won't touch the single trailing +comma as this would unexpectedly change the underlying data type. Note +that this is also the case when commas are used while indexing. This is +a tuple in disguise: ```numpy_array[3, ]```. + +One exception to adding trailing commas is function signatures +containing `*`, `*args`, or `**kwargs`. In this case a trailing comma +is only safe to use on Python 3.6. *Black* will detect if your file is +already 3.6+ only and use trailing commas in this situation. If you +wonder how it knows, it looks for f-strings and existing use of trailing +commas in function signatures that have stars in them. In other words, +if you'd like a trailing comma in this situation and *Black* didn't +recognize it was safe to do so, put it there manually and *Black* will +keep it. + + +### Strings + +*Black* prefers double quotes (`"` and `"""`) over single quotes (`'` +and `'''`). It will replace the latter with the former as long as it +does not result in more backslash escapes than before. + +*Black* also standardizes string prefixes, making them always lowercase. +On top of that, if your code is already Python 3.6+ only or it's using +the `unicode_literals` future import, *Black* will remove `u` from the +string prefix as it is meaningless in those scenarios. + +The main reason to standardize on a single form of quotes is aesthetics. +Having one kind of quotes everywhere reduces reader distraction. +It will also enable a future version of *Black* to merge consecutive +string literals that ended up on the same line (see +[#26](https://github.com/ambv/black/issues/26) for details). + +Why settle on double quotes? They anticipate apostrophes in English +text. They match the docstring standard described in PEP 257. An +empty string in double quotes (`""`) is impossible to confuse with +a one double-quote regardless of fonts and syntax highlighting used. +On top of this, double quotes for strings are consistent with C which +Python interacts a lot with. + +On certain keyboard layouts like US English, typing single quotes is +a bit easier than double quotes. The latter requires use of the Shift +key. My recommendation here is to keep using whatever is faster to type +and let *Black* handle the transformation. + +If you are adopting *Black* in a large project with pre-existing string +conventions (like the popular ["single quotes for data, double quotes for +human-readable strings"](https://stackoverflow.com/a/56190)), you can +pass `--skip-string-normalization` on the command line. This is meant as +an adoption helper, avoid using this for new projects. + +### Numeric literals + +*Black* standardizes most numeric literals to use lowercase letters: `0xab` +instead of `0XAB` and `1e10` instead of `1E10`. Python 2 long literals are +styled as `2L` instead of `2l` to avoid confusion between `l` and `1`. In +Python 3.6+, *Black* adds underscores to long numeric literals to aid +readability: `100000000` becomes `100_000_000`. + +### Line breaks & binary operators + +*Black* will break a line before a binary operator when splitting a block +of code over multiple lines. This is so that *Black* is compliant with the +recent changes in the [PEP 8](https://www.python.org/dev/peps/pep-0008/#should-a-line-break-before-or-after-a-binary-operator) +style guide, which emphasizes that this approach improves readability. + +This behaviour may raise ``W503 line break before binary operator`` warnings in +style guide enforcement tools like Flake8. Since ``W503`` is not PEP 8 compliant, +you should tell Flake8 to ignore these warnings. + + +### Slices + +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. + +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 Flake8 to ignore these warnings. + + +### Parentheses + +Some parentheses are optional in the Python grammar. Any expression can +be wrapped in a pair of parentheses to form an atom. There are a few +interesting cases: + +- `if (...):` +- `while (...):` +- `for (...) in (...):` +- `assert (...), (...)` +- `from X import (...)` +- assignments like: + - `target = (...)` + - `target: type = (...)` + - `some, *un, packing = (...)` + - `augmented += (...)` + +In those cases, parentheses are removed when the entire statement fits +in one line, or if the inner expression doesn't have any delimiters to +further split on. If there is only a single delimiter and the expression +starts or ends with a bracket, the parenthesis can also be successfully +omitted since the existing bracket pair will organize the expression +neatly anyway. Otherwise, the parentheses are added. + +Please note that *Black* does not add or remove any additional nested +parentheses that you might want to have for clarity or further +code organization. For example those parentheses are not going to be +removed: +```py3 +return not (this or that) +decision = (maybe.this() and values > 0) or (maybe.that() and values < 0) +``` + + +### Call chains + +Some popular APIs, like ORMs, use call chaining. This API style is known +as a [fluent interface](https://en.wikipedia.org/wiki/Fluent_interface). +*Black* formats those by treating dots that follow a call or an indexing +operation like a very low priority delimiter. It's easier to show the +behavior than to explain it. Look at the example: +```py3 +def example(session): + result = ( + session.query(models.Customer.id) + .filter( + models.Customer.account_id == account_id, + models.Customer.email == email_address, + ) + .order_by(models.Customer.id.asc()) + .all() + ) +``` + + +### Typing stub files + +PEP 484 describes the syntax for type hints in Python. One of the +use cases for typing is providing type annotations for modules which +cannot contain them directly (they might be written in C, or they might +be third-party, or their implementation may be overly dynamic, and so on). + +To solve this, [stub files with the `.pyi` file +extension](https://www.python.org/dev/peps/pep-0484/#stub-files) can be +used to describe typing information for an external module. Those stub +files omit the implementation of classes and functions they +describe, instead they only contain the structure of the file (listing +globals, functions, and classes with their members). The recommended +code style for those files is more terse than PEP 8: + +* prefer `...` on the same line as the class/function signature; +* avoid vertical whitespace between consecutive module-level functions, + names, or methods and fields within a single class; +* use a single blank line between top-level class definitions, or none + if the classes are very small. + +*Black* enforces the above rules. There are additional guidelines for +formatting `.pyi` file that are not enforced yet but might be in +a future version of the formatter: + +* all function bodies should be empty (contain `...` instead of the body); +* do not use docstrings; +* prefer `...` over `pass`; +* for arguments with a default, use `...` instead of the actual default; +* avoid using string literals in type annotations, stub files support + forward references natively (like Python 3.7 code with `from __future__ + import annotations`); +* use variable annotations instead of type comments, even for stubs that + target older versions of Python; +* for arguments that default to `None`, use `Optional[]` explicitly; +* use `float` instead of `Union[int, float]`. + + +## pyproject.toml + +*Black* is able to read project-specific default values for its +command line options from a `pyproject.toml` file. This is +especially useful for specifying custom `--include` and `--exclude` +patterns for your project. + +**Pro-tip**: If you're asking yourself "Do I need to configure anything?" +the answer is "No". *Black* is all about sensible defaults. + + +### What on Earth is a `pyproject.toml` file? + +[PEP 518](https://www.python.org/dev/peps/pep-0518/) defines +`pyproject.toml` as a configuration file to store build system +requirements for Python projects. With the help of tools +like [Poetry](https://poetry.eustace.io/) or +[Flit](https://flit.readthedocs.io/en/latest/) it can fully replace the +need for `setup.py` and `setup.cfg` files. + + +### Where *Black* looks for the file + +By default *Black* looks for `pyproject.toml` starting from the common +base directory of all files and directories passed on the command line. +If it's not there, it looks in parent directories. It stops looking +when it finds the file, or a `.git` directory, or a `.hg` directory, +or the root of the file system, whichever comes first. + +If you're formatting standard input, *Black* will look for configuration +starting from the current working directory. + +You can also explicitly specify the path to a particular file that you +want with `--config`. In this situation *Black* will not look for any +other file. + +If you're running with `--verbose`, you will see a blue message if +a file was found and used. + + +### Configuration format + +As the file extension suggests, `pyproject.toml` is a [TOML](https://github.com/toml-lang/toml) file. It contains separate +sections for different tools. *Black* is using the `[tool.black]` +section. The option keys are the same as long names of options on +the command line. + +Note that you have to use single-quoted strings in TOML for regular +expressions. It's the equivalent of r-strings in Python. Multiline +strings are treated as verbose regular expressions by Black. Use `[ ]` +to denote a significant space character. + +
+Example `pyproject.toml` + +```toml +[tool.black] +line-length = 88 +py36 = true +include = '\.pyi?$' +exclude = ''' +/( + \.git + | \.hg + | \.mypy_cache + | \.tox + | \.venv + | _build + | buck-out + | build + | dist + + # The following are specific to Black, you probably don't want those. + | blib2to3 + | tests/data +)/ +''' +``` + +
+ +### Lookup hierarchy + +Command-line options have defaults that you can see in `--help`. +A `pyproject.toml` can override those defaults. Finally, options +provided by the user on the command line override both. + +*Black* will only ever use one `pyproject.toml` file during an entire +run. It doesn't look for multiple files, and doesn't compose +configuration from different levels of the file hierarchy. + + +## Editor integration + +### Emacs + +Use [proofit404/blacken](https://github.com/proofit404/blacken). + + +### PyCharm + +1. Install `black`. + +```console +$ pip install black +``` +2. Locate your `black` installation folder. -### Editor integration + On macOS / Linux / BSD: + +```console +$ which black +/usr/local/bin/black # possible location +``` + + On Windows: + +```console +$ where black +%LocalAppData%\Programs\Python\Python36-32\Scripts\black.exe # possible location +``` + +3. Open External tools in PyCharm with `File -> Settings -> Tools -> External Tools`. + +4. Click the + icon to add a new external tool with the following values: + - Name: Black + - Description: Black is the uncompromising Python code formatter. + - Program: + - Arguments: `$FilePath$` + +5. Format the currently opened file by selecting `Tools -> External Tools -> black`. + - Alternatively, you can set a keyboard shortcut by navigating to `Preferences -> Keymap -> External Tools -> External Tools - Black`. + +6. Optionally, run Black on every file save: + + 1. Make sure you have the [File Watcher](https://plugins.jetbrains.com/plugin/7177-file-watchers) plugin installed. + 2. Go to `Preferences -> Tools -> File Watchers` and click `+` to add a new watcher: + - Name: Black + - File type: Python + - Scope: Project Files + - Program: + - Arguments: `$FilePath$` + - Output paths to refresh: `$FilePathRelativeToProjectRoot$` + - Working directory: `$ProjectFileDir$` + +### Vim + +Commands and shortcuts: + +* `:Black` to format the entire file (ranges not supported); +* `:BlackUpgrade` to upgrade *Black* inside the virtualenv; +* `:BlackVersion` to get the current version of *Black* inside the + virtualenv. + +Configuration: +* `g:black_fast` (defaults to `0`) +* `g:black_linelength` (defaults to `88`) +* `g:black_skip_string_normalization` (defaults to `0`) +* `g:black_virtualenv` (defaults to `~/.vim/black`) + +To install with [vim-plug](https://github.com/junegunn/vim-plug): + +``` +Plug 'ambv/black', +``` + +or with [Vundle](https://github.com/VundleVim/Vundle.vim): + +``` +Plugin 'ambv/black' +``` + +or you can copy the plugin from [plugin/black.vim](https://github.com/ambv/black/tree/master/plugin/black.vim). +Let me know if this requires any changes to work with Vim 8's builtin +`packadd`, or Pathogen, and so on. + +This plugin **requires Vim 7.0+ built with Python 3.6+ support**. It +needs Python 3.6 to be able to run *Black* inside the Vim process which +is much faster than calling an external command. + +On first run, the plugin creates its own virtualenv using the right +Python version and automatically installs *Black*. You can upgrade it later +by calling `:BlackUpgrade` and restarting Vim. + +If you need to do anything special to make your virtualenv work and +install *Black* (for example you want to run a version from master), +create a virtualenv manually and point `g:black_virtualenv` to it. +The plugin will use it. + +To run *Black* on save, add the following line to `.vimrc` or `init.vim`: + +``` +autocmd BufWritePre *.py execute ':Black' +``` + +**How to get Vim with Python 3.6?** +On Ubuntu 17.10 Vim comes with Python 3.6 by default. +On macOS with Homebrew run: `brew install vim --with-python3`. +When building Vim from source, use: +`./configure --enable-python3interp=yes`. There's many guides online how +to do this. + + +### Visual Studio Code + +Use the [Python extension](https://marketplace.visualstudio.com/items?itemName=ms-python.python) +([instructions](https://code.visualstudio.com/docs/python/editing#_formatting)). -* Visual Studio Code: [joslarson.black-vscode](https://marketplace.visualstudio.com/items?itemName=joslarson.black-vscode) + +### SublimeText 3 + +Use [sublack plugin](https://github.com/jgirardet/sublack). + + +### IPython Notebook Magic + +Use [blackcellmagic](https://github.com/csurfer/blackcellmagic). + + +### Python Language Server + +If your editor supports the [Language Server Protocol](https://langserver.org/) +(Atom, Sublime Text, Visual Studio Code and many more), you can use +the [Python Language Server](https://github.com/palantir/python-language-server) with the +[pyls-black](https://github.com/rupert/pyls-black) plugin. + + +### Atom/Nuclide + +Use [python-black](https://atom.io/packages/python-black). + + +### Other editors + +Other editors will require external contributions. + +Patches welcome! ✨ 🍰 ✨ Any tool that can pipe code through *Black* using its stdio mode (just -[use `-` as the file name](http://www.tldp.org/LDP/abs/html/special-chars.html#DASHREF2)). +[use `-` as the file name](https://www.tldp.org/LDP/abs/html/special-chars.html#DASHREF2)). The formatted code will be returned on stdout (unless `--check` was passed). *Black* will still emit messages on stderr but that shouldn't affect your use case. -There is currently no integration with any other text editors. Vim and -Atom/Nuclide integration is planned by the author, others will require -external contributions. +This can be used for example with PyCharm's [File Watchers](https://www.jetbrains.com/help/pycharm/file-watchers.html). -Patches welcome! ✨ 🍰 ✨ +## blackd + +`blackd` is a small HTTP server that exposes *Black*'s functionality over +a simple protocol. The main benefit of using it is to avoid paying the +cost of starting up a new *Black* process every time you want to blacken +a file. + +### Usage + +`blackd` is not packaged alongside *Black* by default because it has additional +dependencies. You will need to do `pip install black[d]` to install it. + +You can start the server on the default port, binding only to the local interface +by running `blackd`. You will see a single line mentioning the server's version, +and the host and port it's listening on. `blackd` will then print an access log +similar to most web servers on standard output, merged with any exception traces +caused by invalid formatting requests. + +`blackd` provides even less options than *Black*. You can see them by running +`blackd --help`: + +```text +Usage: blackd [OPTIONS] + +Options: + --bind-host TEXT Address to bind the server to. + --bind-port INTEGER Port to listen on + --version Show the version and exit. + -h, --help Show this message and exit. +``` + +### Protocol + +`blackd` only accepts `POST` requests at the `/` path. The body of the request +should contain the python source code to be formatted, encoded +according to the `charset` field in the `Content-Type` request header. If no +`charset` is specified, `blackd` assumes `UTF-8`. + +There are a few HTTP headers that control how the source is formatted. These +correspond to command line flags for *Black*. There is one exception to this: +`X-Protocol-Version` which if present, should have the value `1`, otherwise the +request is rejected with `HTTP 501` (Not Implemented). + +The headers controlling how code is formatted are: + + - `X-Line-Length`: corresponds to the `--line-length` command line flag. + - `X-Skip-String-Normalization`: corresponds to the `--skip-string-normalization` + command line flag. If present and its value is not the empty string, no string + normalization will be performed. + - `X-Fast-Or-Safe`: if set to `fast`, `blackd` will act as *Black* does when + passed the `--fast` command line flag. + - `X-Python-Variant`: if set to `pyi`, `blackd` will act as *Black* does when + passed the `--pyi` command line flag. Otherwise, its value must correspond to + a Python version. If this value represents at least Python 3.6, `blackd` will + act as *Black* does when passed the `--py36` command line flag. + +If any of these headers are set to invalid values, `blackd` returns a `HTTP 400` +error response, mentioning the name of the problematic header in the message body. + +Apart from the above, `blackd` can produce the following response codes: + + - `HTTP 204`: If the input is already well-formatted. The response body is + empty. + - `HTTP 200`: If formatting was needed on the input. The response body + contains the blackened Python code, and the `Content-Type` header is set + accordingly. + - `HTTP 400`: If the input contains a syntax error. Details of the error are + returned in the response body. + - `HTTP 500`: If there was any kind of error while trying to format the input. + The response body contains a textual representation of the error. + +## Version control integration + +Use [pre-commit](https://pre-commit.com/). Once you [have it +installed](https://pre-commit.com/#install), add this to the +`.pre-commit-config.yaml` in your repository: +```yaml +repos: +- repo: https://github.com/ambv/black + rev: stable + hooks: + - id: black + language_version: python3.6 +``` +Then run `pre-commit install` and you're ready to go. + +Avoid using `args` in the hook. Instead, store necessary configuration +in `pyproject.toml` so that editors and command-line usage of Black all +behave consistently for your project. See *Black*'s own `pyproject.toml` +for an 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 master, this is also an option. + + +## Ignoring unmodified files + +*Black* remembers files it has already formatted, unless the `--diff` flag is used or +code is passed via standard input. This information is stored per-user. The exact +location of the file depends on the *Black* version and the system on which *Black* +is run. The file is non-portable. The standard location on common operating systems +is: + +* Windows: `C:\\Users\\AppData\Local\black\black\Cache\\cache...pickle` +* macOS: `/Users//Library/Caches/black//cache...pickle` +* Linux: `/home//.cache/black//cache...pickle` + +`file-mode` is an int flag that determines whether the file was formatted as 3.6+ only, +as .pyi, and whether string normalization was omitted. ## Testimonials **Dusty Phillips**, [writer](https://smile.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=dusty+phillips): -> Black is opinionated so you don't have to be. +> *Black* is opinionated so you don't have to be. -**Hynek Schlawack**, [creator of `attrs`](http://www.attrs.org/), core +**Hynek Schlawack**, [creator of `attrs`](https://www.attrs.org/), core developer of Twisted and CPython: > An auto-formatter that doesn't suck is all I want for Xmas! @@ -274,6 +887,12 @@ Use the badge in your project's README.md: [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/ambv/black) ``` +Using the badge in README.rst: +``` +.. image:: https://img.shields.io/badge/code%20style-black-000000.svg + :target: https://github.com/ambv/black +``` + Looks like this: [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/ambv/black) @@ -282,10 +901,10 @@ Looks like this: [![Code style: black](https://img.shields.io/badge/code%20style MIT -## Contributing +## Contributing to *Black* -In terms of inspiration, *Black* is about as configurable as *gofmt* and -*rustfmt* are. This is deliberate. +In terms of inspiration, *Black* is about as configurable as *gofmt*. +This is deliberate. Bug reports and fixes are always welcome! However, before you suggest a new feature or configuration knob, ask yourself why you want it. If it @@ -300,6 +919,294 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md). ## Change Log +### 18.9b0 + +* numeric literals are now formatted by *Black* (#452, #461, #464, #469): + + * numeric literals are normalized to include `_` separators on Python 3.6+ code + + * code with `_` in numeric literals is recognized as Python 3.6+ + + * most letters in numeric literals are lowercased (e.g., in `1e10` or `0xab`) + +* added `blackd`, see [its documentation](#blackd) for more info (#349) + +* adjacent string literals are now correctly split into multiple lines (#463) + +* cache is now populated when `--check` is successful for a file which speeds up + consecutive checks of properly formatted unmodified files (#448) + +* code with `_` in numeric literals is recognized as Python 3.6+ (#461) + +* fixed unstable formatting when unpacking big tuples (#267) + +* fixed parsing of `__future__` imports with renames (#389) + +* fixed scope of `# fmt: off` when directly preceding `yield` and other nodes (#385) + +* fixed formatting of lambda expressions with default arguments (#468) + +* fixed ``async for`` statements: *Black* no longer breaks them into separate + lines (#372) + +* note: the Vim plugin stopped registering ``,=`` as a default chord as it turned out + to be a bad idea (#415) + + + +### 18.6b4 + +* hotfix: don't freeze when multiple comments directly precede `# fmt: off` (#371) + + +### 18.6b3 + +* typing stub files (`.pyi`) now have blank lines added after constants (#340) + +* `# fmt: off` and `# fmt: on` are now much more dependable: + + * they now work also within bracket pairs (#329) + + * they now correctly work across function/class boundaries (#335) + + * they now work when an indentation block starts with empty lines or misaligned + comments (#334) + +* made Click not fail on invalid environments; note that Click is right but the + likelihood we'll need to access non-ASCII file paths when dealing with Python source + code is low (#277) + +* fixed improper formatting of f-strings with quotes inside interpolated + expressions (#322) + +* fixed unnecessary slowdown when long list literals where found in a file + +* fixed unnecessary slowdown on AST nodes with very many siblings + +* fixed cannibalizing backslashes during string normalization + +* fixed a crash due to symbolic links pointing outside of the project directory (#338) + + +### 18.6b2 + +* added `--config` (#65) + +* added `-h` equivalent to `--help` (#316) + +* fixed improper unmodified file caching when `-S` was used + +* fixed extra space in string unpacking (#305) + +* fixed formatting of empty triple quoted strings (#313) + +* fixed unnecessary slowdown in comment placement calculation on lines without + comments + + +### 18.6b1 + +* hotfix: don't output human-facing information on stdout (#299) + +* hotfix: don't output cake emoji on non-zero return code (#300) + + +### 18.6b0 + +* added `--include` and `--exclude` (#270) + +* added `--skip-string-normalization` (#118) + +* added `--verbose` (#283) + +* the header output in `--diff` now actually conforms to the unified diff spec + +* fixed long trivial assignments being wrapped in unnecessary parentheses (#273) + +* fixed unnecessary parentheses when a line contained multiline strings (#232) + +* fixed stdin handling not working correctly if an old version of Click was + used (#276) + +* *Black* now preserves line endings when formatting a file in place (#258) + + +### 18.5b1 + +* added `--pyi` (#249) + +* added `--py36` (#249) + +* Python grammar pickle caches are stored with the formatting caches, making + *Black* work in environments where site-packages is not user-writable (#192) + +* *Black* now enforces a PEP 257 empty line after a class-level docstring + (and/or fields) and the first method + +* fixed invalid code produced when standalone comments were present in a trailer + that was omitted from line splitting on a large expression (#237) + +* fixed optional parentheses being removed within `# fmt: off` sections (#224) + +* fixed invalid code produced when stars in very long imports were incorrectly + wrapped in optional parentheses (#234) + +* fixed unstable formatting when inline comments were moved around in + a trailer that was omitted from line splitting on a large expression + (#238) + +* fixed extra empty line between a class declaration and the first + method if no class docstring or fields are present (#219) + +* fixed extra empty line between a function signature and an inner + function or inner class (#196) + + +### 18.5b0 + +* call chains are now formatted according to the + [fluent interfaces](https://en.wikipedia.org/wiki/Fluent_interface) + style (#67) + +* data structure literals (tuples, lists, dictionaries, and sets) are + now also always exploded like imports when they don't fit in a single + line (#152) + +* slices are now formatted according to PEP 8 (#178) + +* parentheses are now also managed automatically on the right-hand side + of assignments and return statements (#140) + +* math operators now use their respective priorities for delimiting multiline + expressions (#148) + +* optional parentheses are now omitted on expressions that start or end + with a bracket and only contain a single operator (#177) + +* empty parentheses in a class definition are now removed (#145, #180) + +* string prefixes are now standardized to lowercase and `u` is removed + on Python 3.6+ only code and Python 2.7+ code with the `unicode_literals` + future import (#188, #198, #199) + +* typing stub files (`.pyi`) are now formatted in a style that is consistent + with PEP 484 (#207, #210) + +* progress when reformatting many files is now reported incrementally + +* fixed trailers (content with brackets) being unnecessarily exploded + into their own lines after a dedented closing bracket (#119) + +* fixed an invalid trailing comma sometimes left in imports (#185) + +* fixed non-deterministic formatting when multiple pairs of removable parentheses + were used (#183) + +* fixed multiline strings being unnecessarily wrapped in optional + parentheses in long assignments (#215) + +* fixed not splitting long from-imports with only a single name + +* fixed Python 3.6+ file discovery by also looking at function calls with + unpacking. This fixed non-deterministic formatting if trailing commas + where used both in function signatures with stars and function calls + with stars but the former would be reformatted to a single line. + +* fixed crash on dealing with optional parentheses (#193) + +* fixed "is", "is not", "in", and "not in" not considered operators for + splitting purposes + +* fixed crash when dead symlinks where encountered + + +### 18.4a4 + +* don't populate the cache on `--check` (#175) + + +### 18.4a3 + +* added a "cache"; files already reformatted that haven't changed on disk + won't be reformatted again (#109) + +* `--check` and `--diff` are no longer mutually exclusive (#149) + +* generalized star expression handling, including double stars; this + fixes multiplication making expressions "unsafe" for trailing commas (#132) + +* *Black* no longer enforces putting empty lines behind control flow statements + (#90) + +* *Black* now splits imports like "Mode 3 + trailing comma" of isort (#127) + +* fixed comment indentation when a standalone comment closes a block (#16, #32) + +* fixed standalone comments receiving extra empty lines if immediately preceding + a class, def, or decorator (#56, #154) + +* fixed `--diff` not showing entire path (#130) + +* fixed parsing of complex expressions after star and double stars in + function calls (#2) + +* fixed invalid splitting on comma in lambda arguments (#133) + +* fixed missing splits of ternary expressions (#141) + + +### 18.4a2 + +* fixed parsing of unaligned standalone comments (#99, #112) + +* fixed placement of dictionary unpacking inside dictionary literals (#111) + +* Vim plugin now works on Windows, too + +* fixed unstable formatting when encountering unnecessarily escaped quotes + in a string (#120) + + +### 18.4a1 + +* added `--quiet` (#78) + +* added automatic parentheses management (#4) + +* added [pre-commit](https://pre-commit.com) integration (#103, #104) + +* fixed reporting on `--check` with multiple files (#101, #102) + +* fixed removing backslash escapes from raw strings (#100, #105) + + +### 18.4a0 + +* added `--diff` (#87) + +* add line breaks before all delimiters, except in cases like commas, to + better comply with PEP 8 (#73) + +* standardize string literals to use double quotes (almost) everywhere + (#75) + +* fixed handling of standalone comments within nested bracketed + expressions; *Black* will no longer produce super long lines or put all + standalone comments at the end of the expression (#22) + +* fixed 18.3a4 regression: don't crash and burn on empty lines with + trailing whitespace (#80) + +* fixed 18.3a4 regression: `# yapf: disable` usage as trailing comment + would cause *Black* to not emit the rest of the file (#95) + +* when CTRL+C is pressed while formatting many files, *Black* no longer + freaks out with a flurry of asyncio-related exceptions + +* only allow up to two empty lines on module level and only single empty + lines within functions (#74) + + ### 18.3a4 * `# fmt: off` and `# fmt: on` are implemented (#5) @@ -340,7 +1247,7 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md). ### 18.3a2 * changed positioning of binary operators to occur at beginning of lines - instead of at the end, following [a recent change to PEP8](https://github.com/python/peps/commit/c59c4376ad233a62ca4b3a6060c81368bd21e85b) + instead of at the end, following [a recent change to PEP 8](https://github.com/python/peps/commit/c59c4376ad233a62ca4b3a6060c81368bd21e85b) (#21) * ignore empty bracket pairs while splitting. This avoids very weirdly @@ -396,3 +1303,28 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md). ## Authors Glued together by [Łukasz Langa](mailto:lukasz@langa.pl). + +Maintained with [Carol Willing](mailto:carolcode@willingconsulting.com), +[Carl Meyer](mailto:carl@oddbird.net), +[Jelle Zijlstra](mailto:jelle.zijlstra@gmail.com), +[Mika Naylor](mailto:mail@autophagy.io), and +[Zsolt Dollenstein](mailto:zsol.zsol@gmail.com). + +Multiple contributions by: +* [Anthony Sottile](mailto:asottile@umich.edu) +* [Artem Malyshev](mailto:proofit404@gmail.com) +* [Christian Heimes](mailto:christian@python.org) +* [Daniel M. Capella](mailto:polycitizen@gmail.com) +* [Eli Treuherz](mailto:eli@treuherz.com) +* Hugo van Kemenade +* [Ivan Katanić](mailto:ivan.katanic@gmail.com) +* [Jonas Obrist](mailto:ojiidotch@gmail.com) +* [Luka Sterbic](mailto:luka.sterbic@gmail.com) +* [Miguel Gaiowski](mailto:miggaiowski@gmail.com) +* [Miroslav Shubernetskiy](mailto:miroslav@miki725.com) +* [Neraste](neraste.herr10@gmail.com) +* [Osaetin Daniel](mailto:osaetindaniel@gmail.com) +* [Peter Bengtsson](mailto:mail@peterbe.com) +* [Stavros Korokithakis](mailto:hi@stavros.io) +* [Sunil Kapil](mailto:snlkapil@gmail.com) +* [Vishwas B Sharma](mailto:sharma.vishwas88@gmail.com)