X-Git-Url: https://git.madduck.net/etc/vim.git/blobdiff_plain/5c6a0dd03f7f6d8694d1b9a62f9770be44f0b809..611737f9cc186d3e6463ef774fdbda4f77055d4c:/README.md?ds=sidebyside diff --git a/README.md b/README.md index d74d436..1cd1ef0 100644 --- a/README.md +++ b/README.md @@ -27,33 +27,28 @@ content instead. possible. -## NOTE: This is an early pre-release +## Installation and Usage -*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**. - -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 +### 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: @@ -78,7 +73,22 @@ Options: used). -## The philosophy behind *Black* +### 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**. + +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 +97,13 @@ 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. +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, @@ -160,20 +171,6 @@ 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. - -*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. - -That's it. The rest of the whitespace formatting rules follow PEP 8 and -are designed to keep `pycodestyle` quiet. - ### Line length @@ -214,6 +211,13 @@ bother you if you overdo it by a few km/h". ### Empty lines +*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. + *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 @@ -228,7 +232,36 @@ entire function, use a docstring or put a leading comment in the function body. -### Editor integration +### 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. + + +## Editor integration * Visual Studio Code: [joslarson.black-vscode](https://marketplace.visualstudio.com/items?itemName=joslarson.black-vscode) * Emacs: [proofit404/blacken](https://github.com/proofit404/blacken) @@ -282,7 +315,7 @@ 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.