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diff --git a/std/style_guide.md b/std/style_guide.md deleted file mode 100644 index be953136f..000000000 --- a/std/style_guide.md +++ /dev/null @@ -1,316 +0,0 @@ -# Deno Style Guide - -## Table of Contents - -## Copyright Headers - -Most modules in the repository should have the following copyright header: - -```ts -// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license. -``` - -If the code originates elsewhere, ensure that the file has the proper copyright -headers. We only allow MIT, BSD, and Apache licensed code. - -## Use underscores, not dashes in filenames. - -Example: Use `file_server.ts` instead of `file-server.ts`. - -## Add tests for new features. - -Each module should contain or be accompanied by tests for its public -functionality. - -## TODO Comments - -TODO comments should usually include an issue or the author's github username in -parentheses. Example: - -```ts -// TODO(ry): Add tests. -// TODO(#123): Support Windows. -// FIXME(#349): Sometimes panics. -``` - -## Meta-programming is discouraged. Including the use of Proxy. - -Be explicit even when it means more code. - -There are some situations where it may make sense to use such techniques, but in -the vast majority of cases it does not. - -## Rust - -Follow Rust conventions and be consistent with existing code. - -## Typescript - -The TypeScript portions of the codebase include `cli/js` for the built-ins and -the standard library `std`. - -### Use TypeScript instead of JavaScript. - -### Use the term "module" instead of "library" or "package". - -For clarity and consistency avoid the terms "library" and "package". Instead use -"module" to refer to a single JS or TS file and also to refer to a directory of -TS/JS code. - -### Do not use the filename `index.ts`/`index.js`. - -Deno does not treat "index.js" or "index.ts" in a special way. By using these -filenames, it suggests that they can be left out of the module specifier when -they cannot. This is confusing. - -If a directory of code needs a default entry point, use the filename `mod.ts`. -The filename `mod.ts` follows Rust’s convention, is shorter than `index.ts`, and -doesn’t come with any preconceived notions about how it might work. - -### Exported functions: max 2 args, put the rest into an options object. - -When designing function interfaces, stick to the following rules. - -1. A function that is part of the public API takes 0-2 required arguments, plus - (if necessary) an options object (so max 3 total). - -2. Optional parameters should generally go into the options object. - - An optional parameter that's not in an options object might be acceptable if - there is only one, and it seems inconceivable that we would add more optional - parameters in the future. - -<!-- prettier-ignore-start --> -<!-- see https://github.com/prettier/prettier/issues/3679 --> - -3. The 'options' argument is the only argument that is a regular 'Object'. - - Other arguments can be objects, but they must be distinguishable from a - 'plain' Object runtime, by having either: - - - a distinguishing prototype (e.g. `Array`, `Map`, `Date`, `class MyThing`) - - a well-known symbol property (e.g. an iterable with `Symbol.iterator`). - - This allows the API to evolve in a backwards compatible way, even when the - position of the options object changes. - -<!-- prettier-ignore-end --> - -```ts -// BAD: optional parameters not part of options object. (#2) -export function resolve( - hostname: string, - family?: "ipv4" | "ipv6", - timeout?: number -): IPAddress[] {} - -// GOOD. -export interface ResolveOptions { - family?: "ipv4" | "ipv6"; - timeout?: number; -} -export function resolve( - hostname: string, - options: ResolveOptions = {} -): IPAddress[] {} -``` - -```ts -export interface Environment { - [key: string]: string; -} - -// BAD: `env` could be a regular Object and is therefore indistinguishable -// from an options object. (#3) -export function runShellWithEnv(cmdline: string, env: Environment): string {} - -// GOOD. -export interface RunShellOptions { - env: Environment; -} -export function runShellWithEnv( - cmdline: string, - options: RunShellOptions -): string {} -``` - -```ts -// BAD: more than 3 arguments (#1), multiple optional parameters (#2). -export function renameSync( - oldname: string, - newname: string, - replaceExisting?: boolean, - followLinks?: boolean -) {} - -// GOOD. -interface RenameOptions { - replaceExisting?: boolean; - followLinks?: boolean; -} -export function renameSync( - oldname: string, - newname: string, - options: RenameOptions = {} -) {} -``` - -```ts -// BAD: too many arguments. (#1) -export function pwrite( - fd: number, - buffer: TypedArray, - offset: number, - length: number, - position: number -) {} - -// BETTER. -export interface PWrite { - fd: number; - buffer: TypedArray; - offset: number; - length: number; - position: number; -} -export function pwrite(options: PWrite) {} -``` - -### Minimize dependencies; do not make circular imports. - -Although `cli/js` and `std` have no external dependencies, we must still be -careful to keep internal dependencies simple and manageable. In particular, be -careful not to introduce circular imports. - -### If a filename starts with an underscore: `_foo.ts`, do not link to it. - -Sometimes there maybe situations where an internal module is necessary but its -API is not meant to be stable or linked to. In this case prefix it with an -underscore. By convention, only files in its own directory should import it. - -### Use JSDoc for exported symbols. - -We strive for complete documentation. Every exported symbol ideally should have -a documentation line. - -If possible, use a single line for the JS Doc. Example: - -```ts -/** foo does bar. */ -export function foo() { - // ... -} -``` - -It is important that documentation is easily human readable, but there is also a -need to provide additional styling information to ensure generated documentation -is more rich text. Therefore JSDoc should generally follow markdown markup to -enrich the text. - -While markdown supports HTML tags, it is forbidden in JSDoc blocks. - -Code string literals should be braced with the back-tick (\`) instead of quotes. -For example: - -```ts -/** Import something from the `deno` module. */ -``` - -Do not document function arguments unless they are non-obvious of their intent -(though if they are non-obvious intent, the API should be considered anyways). -Therefore `@param` should generally not be used. If `@param` is used, it should -not include the `type` as TypeScript is already strongly typed. - -```ts -/** - * Function with non obvious param. - * @param foo Description of non obvious parameter. - */ -``` - -Vertical spacing should be minimized whenever possible. Therefore single line -comments should be written as: - -```ts -/** This is a good single line JSDoc. */ -``` - -And not - -```ts -/** - * This is a bad single line JSDoc. - */ -``` - -Code examples should not utilise the triple-back tick (\`\`\`) notation or tags. -They should just be marked by indentation, which requires a break before the -block and 6 additional spaces for each line of the example. This is 4 more than -the first column of the comment. For example: - -```ts -/** A straight forward comment and an example: - * - * import { foo } from "deno"; - * foo("bar"); - */ -``` - -Code examples should not contain additional comments. It is already inside a -comment. If it needs further comments it is not a good example. - -### Each module should come with a test module. - -Every module with public functionality `foo.ts` should come with a test module -`foo_test.ts`. A test for a `cli/js` module should go in `cli/js/tests` due to -their different contexts, otherwise it should just be a sibling to the tested -module. - -### Unit Tests should be explicit. - -For a better understanding of the tests, function should be correctly named as -its prompted throughout the test command. Like: - -``` -test myTestFunction ... ok -``` - -Example of test: - -```ts -import { assertEquals } from "https://deno.land/std@v0.11/testing/asserts.ts"; -import { foo } from "./mod.ts"; - -Deno.test("myTestFunction" function() { - assertEquals(foo(), { bar: "bar" }); -}); -``` - -### Top level functions should not use arrow syntax. - -Top level functions should use the `function` keyword. Arrow syntax should be -limited to closures. - -Bad - -```ts -export const foo = (): string => { - return "bar"; -}; -``` - -Good - -```ts -export function foo(): string { - return "bar"; -} -``` - -### `std` - -#### Do not depend on external code. - -`https://deno.land/std/` is intended to be baseline functionality that all Deno -programs can rely on. We want to guarantee to users that this code does not -include potentially unreviewed third party code. |