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# revive

Fast, configurable, extensible, flexible, and beautiful linter for Go. Drop-in replacement of golint. **`Revive` provides a framework for development of custom rules, and lets you define a strict preset for enhancing your development & code review processes**.

<p align="center">
  <img src="./assets/logo.png" alt="" width="300">
  <br>
  Logo by <a href="https://github.com/hawkgs">Georgi Serev</a>
</p>

Here's how `revive` is different from `golint`:

- Allows to enable or disable rules using a configuration file.
- Allows to configure the linting rules with a TOML file.
- 2x faster running the same rules as golint.
- Provides functionality for disabling a specific rule or the entire linter for a file or a range of lines.
  - `golint` allows this only for generated files.
- Optional type checking. Most rules in golint do not require type checking. If you disable them in the config file, revive will run over 6x faster than golint.
- Provides multiple formatters which let us customize the output.
- Allows to customize the return code for the entire linter or based on the failure of only some rules.
- _Everyone can extend it easily with custom rules or formatters._
- `Revive` provides more rules compared to `golint`.

## Who uses Revive

- [`tidb`](https://github.com/pingcap/tidb) - TiDB is a distributed HTAP database compatible with the MySQL protocol
- [`grafana`](https://github.com/grafana/grafana) - The tool for beautiful monitoring and metric analytics & dashboards for Graphite, InfluxDB & Prometheus & More
- [`etcd`](https://github.com/etcd-io/etcd) - Distributed reliable key-value store for the most critical data of a distributed system
- [`ferret`](https://github.com/MontFerret/ferret) - Declarative web scraping
- [`gopass`](https://github.com/gopasspw/gopass) - The slightly more awesome standard unix password manager for teams
- [`gitea`](https://github.com/go-gitea/gitea) - Git with a cup of tea, painless self-hosted git service
- [`excelize`](https://github.com/360EntSecGroup-Skylar/excelize) - Go library for reading and writing Microsoft Excel™ (XLSX) files
- [`aurora`](https://github.com/xuri/aurora) - aurora is a web-based Beanstalk queue server console written in Go
- [`soar`](https://github.com/XiaoMi/soar) - SQL Optimizer And Rewriter
- [`gorush`](https://github.com/appleboy/gorush) - A push notification server written in Go (Golang)a
- [`dry`](https://github.com/moncho/dry) - dry - A Docker manager for the terminal.
- [`go-echarts`](https://github.com/chenjiandongx/go-echarts) - The adorable charts library for Golang
- [`reviewdog`](https://github.com/reviewdog/reviewdog) - Automated code review tool integrated with any code analysis tools regardless of programming language
- [`rudder-server`](https://github.com/rudderlabs/rudder-server) - Privacy and Security focused Segment-alternative, in Golang and React.
- [`sklearn`](https://github.com/pa-m/sklearn) - A partial port of scikit-learn written in Go.
- [`protoc-gen-doc`](https://github.com/pseudomuto/protoc-gen-doc) - Documentation generator plugin for Google Protocol Buffers.
- [`llvm`](https://github.com/llir/llvm) - Library for interacting with LLVM IR in pure Go.
- [`jenkins-library`](https://github.com/SAP/jenkins-library) - Jenkins shared library for Continuous Delivery pipelines by SAP.
- [`pd`](https://github.com/tikv/pd) - Placement driver for TiKV.
- [`shellhub`](https://github.com/shellhub-io/shellhub) - ShellHub enables teams to easily access any Linux device behind firewall and NAT.
- [`lorawan-stack`](https://github.com/TheThingsNetwork/lorawan-stack) - The Things Network Stack for LoRaWAN V3
- [`gin-jwt`](https://github.com/appleboy/gin-jwt) - This is a JWT middleware for Gin framework.
- [`gofight`](https://github.com/appleboy/gofight) - Testing API Handler written in Golang.
- [`Beaver`](https://github.com/Clivern/Beaver) - A Real Time Messaging Server.
- [`ggz`](https://github.com/go-ggz/ggz) - An URL shortener service written in Golang
- [`Codeac.io`](https://www.codeac.io?ref=revive) - Automated code review service integrates with GitHub, Bitbucket and GitLab (even self-hosted) and helps you fight technical debt.

*Open a PR to add your project*.

<p align="center">
  <img src="./assets/demo.svg" alt="" width="700">
</p>

<!-- TOC -->

- [revive](#revive)
  - [Usage](#usage)
    - [Text Editors](#text-editors)
    - [Continuous Integration](#continuous-integration)
    - [Bazel](#bazel)
    - [Installation](#installation)
    - [Command Line Flags](#command-line-flags)
    - [Sample Invocations](#sample-invocations)
    - [Comment Annotations](#comment-annotations)
    - [Configuration](#configuration)
    - [Default Configuration](#default-configuration)
    - [Custom Configuration](#custom-configuration)
    - [Recommended Configuration](#recommended-configuration)
  - [Available Rules](#available-rules)
  - [Configurable rules](#configurable-rules)
    - [`var-naming`](#var-naming)
  - [Available Formatters](#available-formatters)
    - [Friendly](#friendly)
    - [Stylish](#stylish)
    - [Default](#default)
    - [Plain](#plain)
    - [Unix](#unix)
  - [Extensibility](#extensibility)
    - [Custom Rule](#custom-rule)
      - [Example](#example)
    - [Custom Formatter](#custom-formatter)
  - [Speed Comparison](#speed-comparison)
    - [golint](#golint)
    - [revive](#revive)
  - [Overriding colorization detection](#overriding-colorization-detection)
  - [Contributors](#contributors)
  - [License](#license)

<!-- /TOC -->

## Usage

Since the default behavior of `revive` is compatible with `golint`, without providing any additional flags, the only difference you'd notice is faster execution.

`revive` supports a `-config` flag whose value should correspond to a TOML file describing which rules to use for `revive`'s linting. If not provided, `revive` will try to use a global config file (assumed to be located at `$HOME/revive.toml`). Otherwise, if no configuration TOML file is found then `revive` uses a built-in set of default linting rules.

### Bazel

If you want to use revive with Bazel, take a look at the [rules](https://github.com/atlassian/bazel-tools/tree/master/gorevive) that Atlassian maintains.

### Text Editors

- Support for VSCode in [vscode-go](https://github.com/Microsoft/vscode-go/pull/1699).
- Support for GoLand via [File Watchers](https://dev.to/s0xzwasd/configure-revive-go-linter-in-goland-2ggl).  
- Support for Atom via [linter-revive](https://github.com/morphy2k/linter-revive).
- Support for vim via [dense-analysis/ale](https://github.com/dense-analysis/ale).

```vim
let g:ale_linters = {
\   'go': ['revive'],
\}
```

### GitHub Actions

- [Revive Action](https://github.com/marketplace/actions/revive-action) with annotation support

### Continuous Integration

[Codeac.io](https://www.codeac.io?ref=revive) - Automated code review service integrates with GitHub, Bitbucket and GitLab (even self-hosted) and helps you fight technical debt. Check your [pull-requests](https://www.codeac.io/documentation/pull-requests.html?ref=revive) with [revive](https://www.codeac.io/documentation/revive-configuration.html?ref=revive) automatically. (free for open-source projects)

### Installation

```bash
go get -u github.com/mgechev/revive
```

### Command Line Flags

`revive` accepts three command line parameters:

- `-config [PATH]` - path to config file in TOML format, defaults to `$HOME/revive.toml` if present.
- `-exclude [PATTERN]` - pattern for files/directories/packages to be excluded for linting. You can specify the files you want to exclude for linting either as package name (i.e. `github.com/mgechev/revive`), list them as individual files (i.e. `file.go`), directories (i.e. `./foo/...`), or any combination of the three.
- `-formatter [NAME]` - formatter to be used for the output. The currently available formatters are:

  - `default` - will output the failures the same way that `golint` does.
  - `json` - outputs the failures in JSON format.
  - `ndjson` - outputs the failures as stream in newline delimited JSON (NDJSON) format.
  - `friendly` - outputs the failures when found. Shows summary of all the failures.
  - `stylish` - formats the failures in a table. Keep in mind that it doesn't stream the output so it might be perceived as slower compared to others.
  - `checkstyle` - outputs the failures in XML format compatible with that of Java's [Checkstyle](https://checkstyle.org/).

### Sample Invocations

```shell
revive -config revive.toml -exclude file1.go -exclude file2.go -formatter friendly github.com/mgechev/revive package/...
```

- The command above will use the configuration from `revive.toml`
- `revive` will ignore `file1.go` and `file2.go`
- The output will be formatted with the `friendly` formatter
- The linter will analyze `github.com/mgechev/revive` and the files in `package`

### Comment Directives

Using comments, you can disable the linter for the entire file or only range of lines:

```go
//revive:disable

func Public() {}
//revive:enable
```

The snippet above, will disable `revive` between the `revive:disable` and `revive:enable` comments. If you skip `revive:enable`, the linter will be disabled for the rest of the file.

With `revive:disable-next-line` and `revive:disable-line` you can disable `revive` on a particular code line.

You can do the same on a rule level. In case you want to disable only a particular rule, you can use:

```go
//revive:disable:unexported-return
func Public() private {
  return private
}
//revive:enable:unexported-return
```

This way, `revive` will not warn you for that you're returning an object of an unexported type, from an exported function.

You can document why you disable the linter by adding a trailing text in the directive, for example

```go
//revive:disable Until the code is stable
```
```go
//revive:disable:cyclomatic High complexity score but easy to understand
```

You can also configure `revive` to enforce documenting linter disabling directives by adding

```toml
[directive.specify-disable-reason]
```

in the configuration. You can set the severity (defaults to _warning_) of the violation of this directive

```toml
[directive.specify-disable-reason]
    severity = "error"
```

### Configuration

`revive` can be configured with a TOML file. Here's a sample configuration with explanation for the individual properties:

```toml
# When set to false, ignores files with "GENERATED" header, similar to golint
ignoreGeneratedHeader = true

# Sets the default severity to "warning"
severity = "warning"

# Sets the default failure confidence. This means that linting errors
# with less than 0.8 confidence will be ignored.
confidence = 0.8

# Sets the error code for failures with severity "error"
errorCode = 0

# Sets the error code for failures with severity "warning"
warningCode = 0

# Configuration of the `cyclomatic` rule. Here we specify that
# the rule should fail if it detects code with higher complexity than 10.
[rule.cyclomatic]
  arguments = [10]

# Sets the severity of the `package-comments` rule to "error".
[rule.package-comments]
  severity = "error"
```

### Default Configuration

The default configuration of `revive` can be found at `defaults.toml`. This will enable all rules available in `golint` and use their default configuration (i.e. the way they are hardcoded in `golint`).

```shell
revive -config defaults.toml github.com/mgechev/revive
```

This will use the configuration file `defaults.toml`, the `default` formatter, and will run linting over the `github.com/mgechev/revive` package.

### Custom Configuration

```shell
revive -config config.toml -formatter friendly github.com/mgechev/revive
```

This will use `config.toml`, the `friendly` formatter, and will run linting over the `github.com/mgechev/revive` package.

### Recommended Configuration

The following snippet contains the recommended `revive` configuration that you can use in your project:

```toml
ignoreGeneratedHeader = false
severity = "warning"
confidence = 0.8
errorCode = 0
warningCode = 0

[rule.blank-imports]
[rule.context-as-argument]
[rule.context-keys-type]
[rule.dot-imports]
[rule.error-return]
[rule.error-strings]
[rule.error-naming]
[rule.exported]
[rule.if-return]
[rule.increment-decrement]
[rule.var-naming]
[rule.var-declaration]
[rule.package-comments]
[rule.range]
[rule.receiver-naming]
[rule.time-naming]
[rule.unexported-return]
[rule.indent-error-flow]
[rule.errorf]
[rule.empty-block]
[rule.superfluous-else]
[rule.unused-parameter]
[rule.unreachable-code]
[rule.redefines-builtin-id]
```

## Available Rules

List of all available rules. The rules ported from `golint` are left unchanged and indicated in the `golint` column.

| Name                  | Config | Description                                                      | `golint` | Typed |
| --------------------- | :----: | :--------------------------------------------------------------- | :------: | :---: |
| [`context-keys-type`](./RULES_DESCRIPTIONS.md#context-key-types)   |  n/a   | Disallows the usage of basic types in `context.WithValue`.       |   yes    |  yes  |
| [`time-naming`](./RULES_DESCRIPTIONS.md#time-naming)         |  n/a   | Conventions around the naming of time variables.                 |   yes    |  yes  |
| [`var-declaration`](./RULES_DESCRIPTIONS.md#var-declaration)     |  n/a   | Reduces redundancies around variable declaration.                |   yes    |  yes  |
| [`unexported-return`](./RULES_DESCRIPTIONS.md#unexported-return)   |  n/a   | Warns when a public return is from unexported type.              |   yes    |  yes  |
| [`errorf`](./RULES_DESCRIPTIONS.md#errorf)              |  n/a   | Should replace `errors.New(fmt.Sprintf())` with `fmt.Errorf()`   |   yes    |  yes  |
| [`blank-imports`](./RULES_DESCRIPTIONS.md#blank-imports)       |  n/a   | Disallows blank imports                                          |   yes    |  no   |
| [`context-as-argument`](./RULES_DESCRIPTIONS.md#context-as-argument) |  n/a   | `context.Context` should be the first argument of a function.    |   yes    |  no   |
| [`dot-imports`](./RULES_DESCRIPTIONS.md#dot-imports)         |  n/a   | Forbids `.` imports.                                             |   yes    |  no   |
| [`error-return`](./RULES_DESCRIPTIONS.md#error-return)        |  n/a   | The error return parameter should be last.                       |   yes    |  no   |
| [`error-strings`](./RULES_DESCRIPTIONS.md#error-strings)       |  n/a   | Conventions around error strings.                                |   yes    |  no   |
| [`error-naming`](./RULES_DESCRIPTIONS.md#error-naming)        |  n/a   | Naming of error variables.                                       |   yes    |  no   |
| [`exported`](./RULES_DESCRIPTIONS.md#exported)            |  n/a   | Naming and commenting conventions on exported symbols.           |   yes    |  no   |
| [`if-return`](./RULES_DESCRIPTIONS.md#if-return)           |  n/a   | Redundant if when returning an error.                            |   yes    |  no   |
| [`increment-decrement`](./RULES_DESCRIPTIONS.md#increment-decrement) |  n/a   | Use `i++` and `i--` instead of `i += 1` and `i -= 1`.            |   yes    |  no   |
| [`var-naming`](./RULES_DESCRIPTIONS.md#var-naming)          |  whitelist & blacklist of initialisms   | Naming rules.                                                    |   yes    |  no   |
| [`package-comments`](./RULES_DESCRIPTIONS.md#package-comments)    |  n/a   | Package commenting conventions.                                  |   yes    |  no   |
| [`range`](./RULES_DESCRIPTIONS.md#range)               |  n/a   | Prevents redundant variables when iterating over a collection.   |   yes    |  no   |
| [`receiver-naming`](./RULES_DESCRIPTIONS.md#receiver-naming)     |  n/a   | Conventions around the naming of receivers.                      |   yes    |  no   |
| [`indent-error-flow`](./RULES_DESCRIPTIONS.md#indent-error-flow)   |  n/a   | Prevents redundant else statements.                              |   yes    |  no   |
| [`argument-limit`](./RULES_DESCRIPTIONS.md#argument-limit)      |  int   | Specifies the maximum number of arguments a function can receive |    no    |  no   |
| [`cyclomatic`](./RULES_DESCRIPTIONS.md#cyclomatic)          |  int   | Sets restriction for maximum Cyclomatic complexity.              |    no    |  no   |
| [`max-public-structs`](./RULES_DESCRIPTIONS.md#max-public-structs)  |  int   | The maximum number of public structs in a file.                  |    no    |  no   |
| [`file-header`](./RULES_DESCRIPTIONS.md#file-header)         | string | Header which each file should have.                              |    no    |  no   |
| [`empty-block`](./RULES_DESCRIPTIONS.md#empty-block)         |  n/a   | Warns on empty code blocks                                       |    no    |  yes   |
| [`superfluous-else`](./RULES_DESCRIPTIONS.md#superfluous-else)    |  n/a   | Prevents redundant else statements (extends [`indent-error-flow`](./RULES_DESCRIPTIONS.md#indent-error-flow)) |    no    |  no   |
| [`confusing-naming`](./RULES_DESCRIPTIONS.md#confusing-naming)    |  n/a   | Warns on methods with names that differ only by capitalization   |    no    |  no   |
| [`get-return`](./RULES_DESCRIPTIONS.md#get-return)          |  n/a   | Warns on getters that do not yield any result                    |    no    |  no   |
| [`modifies-parameter`](./RULES_DESCRIPTIONS.md#modifies-parameter)  |  n/a   | Warns on assignments to function parameters                      |    no    |  no   |
| [`confusing-results`](./RULES_DESCRIPTIONS.md#confusing-results)   |  n/a   | Suggests to name potentially confusing function results          |    no    |  no   |
| [`deep-exit`](./RULES_DESCRIPTIONS.md#deep-exit)           |  n/a   | Looks for program exits in funcs other than `main()` or `init()` |    no    |  no   |
| [`unused-parameter`](./RULES_DESCRIPTIONS.md#unused-parameter)    |  n/a   | Suggests to rename or remove unused function parameters          |    no    |  no   |
| [`unreachable-code`](./RULES_DESCRIPTIONS.md#unreachable-code)    |  n/a   | Warns on unreachable code                                        |    no    |  no   |
| [`add-constant`](./RULES_DESCRIPTIONS.md#add-constant)        |  map   | Suggests using constant for magic numbers and string literals    |    no    |  no   |
| [`flag-parameter`](./RULES_DESCRIPTIONS.md#flag-parameter)      |  n/a   | Warns on boolean parameters that create a control coupling       |    no    |  no   |
| [`unnecessary-stmt`](./RULES_DESCRIPTIONS.md#unnecessary-stmt)    |  n/a   | Suggests removing or simplifying unnecessary statements          |    no    |  no   |
| [`struct-tag`](./RULES_DESCRIPTIONS.md#struct-tag)          |  n/a   | Checks common struct tags like `json`,`xml`,`yaml`               |    no    |  no   |
| [`modifies-value-receiver`](./RULES_DESCRIPTIONS.md#modifies-value-receiver) |  n/a   | Warns on assignments to value-passed method receivers        |    no    |  yes  |
| [`constant-logical-expr`](./RULES_DESCRIPTIONS.md#constant-logical-expr)   |  n/a   | Warns on constant logical expressions                        |    no    |  no   |
| [`bool-literal-in-expr`](./RULES_DESCRIPTIONS.md#bool-literal-in-expr)|  n/a   | Suggests removing Boolean literals from logic expressions        |    no    |  no   |
| [`redefines-builtin-id`](./RULES_DESCRIPTIONS.md#redefines-builtin-id)|  n/a   | Warns on redefinitions of builtin identifiers                    |    no    |  no   |
| [`function-result-limit`](./RULES_DESCRIPTIONS.md#function-result-limit) |  int | Specifies the maximum number of results a function can return    |    no    |  no   |
| [`imports-blacklist`](./RULES_DESCRIPTIONS.md#imports-blacklist)   | []string | Disallows importing the specified packages                     |    no    |  no   |
| [`range-val-in-closure`](./RULES_DESCRIPTIONS.md#range-val-in-closure)|  n/a   | Warns if range value is used in a closure dispatched as goroutine|    no    |  no   |
| [`range-val-address`](./RULES_DESCRIPTIONS.md#range-val-address)|  n/a   | Warns if address of range value is used dangerously |    no    |  no   |
| [`waitgroup-by-value`](./RULES_DESCRIPTIONS.md#waitgroup-by-value)  |  n/a   | Warns on functions taking sync.WaitGroup as a by-value parameter |    no    |  no   |
| [`atomic`](./RULES_DESCRIPTIONS.md#atomic)              |  n/a   | Check for common mistaken usages of the `sync/atomic` package    |    no    |  no   |
| [`empty-lines`](./RULES_DESCRIPTIONS.md#empty-lines)   | n/a | Warns when there are heading or trailing newlines in a block              |    no    |  no   |
| [`line-length-limit`](./RULES_DESCRIPTIONS.md#line-length-limit)   | int    | Specifies the maximum number of characters in a line             |    no    |  no   |
| [`call-to-gc`](./RULES_DESCRIPTIONS.md#call-to-gc)   | n/a    | Warns on explicit call to the garbage collector    |    no    |  no   |
| [`duplicated-imports`](./RULES_DESCRIPTIONS.md#duplicated-imports) | n/a  | Looks for packages that are imported two or more times   |    no    |  no   |
| [`import-shadowing`](./RULES_DESCRIPTIONS.md#import-shadowing)   | n/a    | Spots identifiers that shadow an import    |    no    |  no   |
| [`bare-return`](./RULES_DESCRIPTIONS.md#bare-return) | n/a  | Warns on bare returns   |    no    |  no   |
| [`unused-receiver`](./RULES_DESCRIPTIONS.md#unused-receiver)   | n/a    | Suggests to rename or remove unused method receivers    |    no    |  no   |
| [`unhandled-error`](./RULES_DESCRIPTIONS.md#unhandled-error)   | []string   | Warns on unhandled errors returned by funcion calls    |    no    |  yes   |
| [`cognitive-complexity`](./RULES_DESCRIPTIONS.md#cognitive-complexity)          |  int   | Sets restriction for maximum Cognitive complexity.              |    no    |  no   |
| [`string-of-int`](./RULES_DESCRIPTIONS.md#string-of-int)          |  n/a   | Warns on suspicious casts from int to string            |    no    |  yes   |
| [`early-return`](./RULES_DESCRIPTIONS.md#early-return)          |  n/a   | Spots if-then-else statements that can be refactored to simplify code reading            |    no    |  no   |
| [`unconditional-recursion`](./RULES_DESCRIPTIONS.md#unconditional-recursion)          |  n/a   | Warns on function calls that will lead to (direct) infinite recursion |    no    |  no   |
| [`identical-branches`](./RULES_DESCRIPTIONS.md#identical-branches)          |  n/a   | Spots if-then-else statements with identical `then` and `else` branches       |    no    |  no   |
| [`defer`](./RULES_DESCRIPTIONS.md#defer)          |  map   |  Warns on some [defer gotchas](https://blog.learngoprogramming.com/5-gotchas-of-defer-in-go-golang-part-iii-36a1ab3d6ef1)       |    no    |  no   |
| [`unexported-naming`](./RULES_DESCRIPTIONS.md#unexported-naming)          |  n/a   |  Warns on wrongly named un-exported symbols       |    no    |  no   |
| [`function-length`](./RULES_DESCRIPTIONS.md#function-length)          |  n/a   |  Warns on functions exceeding the statements or lines max |    no    |  no   |

## Configurable rules

Here you can find how you can configure some of the existing rules:

### `var-naming`

This rule accepts two slices of strings, a whitelist and a blacklist of initialisms. By default the rule behaves exactly as the alternative in `golint` but optionally, you can relax it (see [golint/lint/issues/89](https://github.com/golang/lint/issues/89))

```toml
[rule.var-naming]
  arguments = [["ID"], ["VM"]]
```

This way, revive will not warn for identifier called `customId` but will warn that `customVm` should be called `customVM`.

## Available Formatters

This section lists all the available formatters and provides a screenshot for each one.

### Friendly

![Friendly formatter](/assets/formatter-friendly.png)

### Stylish

![Stylish formatter](/assets/formatter-stylish.png)

### Default

The default formatter produces the same output as `golint`.

![Default formatter](/assets/formatter-default.png)

### Plain

The plain formatter produces the same output as the default formatter and appends URL to the rule description.

![Plain formatter](/assets/formatter-plain.png)

### Unix

The unix formatter produces the same output as the default formatter but surrounds the rules in `[]`.

![Unix formatter](/assets/formatter-unix.png)

## Extensibility

The tool can be extended with custom rules or formatters. This section contains additional information on how to implement such.

**To extend the linter with a custom rule or a formatter you'll have to push it to this repository or fork it**. This is due to the limited `-buildmode=plugin` support which [works only on Linux (with known issues)](https://golang.org/pkg/plugin/).

### Custom Rule

Each rule needs to implement the `lint.Rule` interface:

```go
type Rule interface {
	Name() string
	Apply(*File, Arguments) []Failure
}
```

The `Arguments` type is an alias of the type `[]interface{}`. The arguments of the rule are passed from the configuration file.

#### Example

Let's suppose we have developed a rule called `BanStructNameRule` which disallow us to name a structure with given identifier. We can set the banned identifier by using the TOML configuration file:

```toml
[rule.ban-struct-name]
  arguments = ["Foo"]
```

With the snippet above we:

- Enable the rule with name `ban-struct-name`. The `Name()` method of our rule should return a string which matches `ban-struct-name`.
- Configure the rule with the argument `Foo`. The list of arguments will be passed to `Apply(*File, Arguments)` together with the target file we're linting currently.

A sample rule implementation can be found [here](/rule/argument-limit.go).

### Custom Formatter

Each formatter needs to implement the following interface:

```go
type Formatter interface {
	Format(<-chan Failure, Config) (string, error)
	Name() string
}
```

The `Format` method accepts a channel of `Failure` instances and the configuration of the enabled rules. The `Name()` method should return a string different from the names of the already existing rules. This string is used when specifying the formatter when invoking the `revive` CLI tool.

For a sample formatter, take a look at [this file](/formatter/json.go).

## Speed Comparison

Compared to `golint`, `revive` performs better because it lints the files for each individual rule into a separate goroutine. Here's a basic performance benchmark on MacBook Pro Early 2013 run on kubernetes:

### golint

```shell
time golint kubernetes/... > /dev/null

real    0m54.837s
user    0m57.844s
sys     0m9.146s
```

### revive

```shell
# no type checking
time revive -config untyped.toml kubernetes/... > /dev/null

real    0m8.471s
user    0m40.721s
sys     0m3.262s
```

Keep in mind that if you use rules which require type checking, the performance may drop to 2x faster than `golint`:

```shell
# type checking enabled
time revive kubernetes/... > /dev/null

real    0m26.211s
user    2m6.708s
sys     0m17.192s
```

Currently, type checking is enabled by default. If you want to run the linter without type checking, remove all typed rules from the configuration file.

## Overriding colorization detection

By default, `revive` determines whether or not to colorize its output based on whether it's connected to a TTY or not.
This works for most use cases, but may not behave as expected if you use `revive` in a pipeline of commands,
where STDOUT is being piped to another command.

To force colorization, add `REVIVE_FORCE_COLOR=1` to the environment you're running in. For example:

```shell
REVIVE_FORCE_COLOR=1 revive -formatter friendly ./... | tee revive.log
```

## Contributors

[<img alt="mgechev" src="https://avatars1.githubusercontent.com/u/455023?v=4&s=117" width="117">](https://github.com/mgechev) |[<img alt="chavacava" src="https://avatars2.githubusercontent.com/u/25788468?v=4&s=117" width="117">](https://github.com/chavacava) |[<img alt="renovate-bot" src="https://avatars0.githubusercontent.com/u/25180681?v=4&s=117" width="117">](https://github.com/renovate-bot) |[<img alt="xuri" src="https://avatars2.githubusercontent.com/u/2809468?v=4&s=117" width="117">](https://github.com/xuri) |[<img alt="dshemin" src="https://avatars3.githubusercontent.com/u/11780307?v=4&s=117" width="117">](https://github.com/dshemin) |[<img alt="gsamokovarov" src="https://avatars0.githubusercontent.com/u/604618?v=4&s=117" width="117">](https://github.com/gsamokovarov) |
:---: |:---: |:---: |:---: |:---: |:---: |
[mgechev](https://github.com/mgechev) |[chavacava](https://github.com/chavacava) |[renovate-bot](https://github.com/renovate-bot) |[xuri](https://github.com/xuri) |[dshemin](https://github.com/dshemin) |[gsamokovarov](https://github.com/gsamokovarov) |

[<img alt="morphy2k" src="https://avatars2.githubusercontent.com/u/4280578?v=4&s=117" width="117">](https://github.com/morphy2k) |[<img alt="tymonx" src="https://avatars2.githubusercontent.com/u/8367378?v=4&s=117" width="117">](https://github.com/tymonx) |[<img alt="markelog" src="https://avatars0.githubusercontent.com/u/945528?v=4&s=117" width="117">](https://github.com/markelog) |[<img alt="tamird" src="https://avatars0.githubusercontent.com/u/1535036?v=4&s=117" width="117">](https://github.com/tamird) |[<img alt="mapreal19" src="https://avatars2.githubusercontent.com/u/3055997?v=4&s=117" width="117">](https://github.com/mapreal19) |[<img alt="Clivern" src="https://avatars3.githubusercontent.com/u/1634427?v=4&s=117" width="117">](https://github.com/Clivern) |
:---: |:---: |:---: |:---: |:---: |:---: |
[morphy2k](https://github.com/morphy2k) |[tymonx](https://github.com/tymonx) |[markelog](https://github.com/markelog) |[tamird](https://github.com/tamird) |[mapreal19](https://github.com/mapreal19) |[Clivern](https://github.com/Clivern) |

[<img alt="AragurDEV" src="https://avatars0.githubusercontent.com/u/11004008?v=4&s=117" width="117">](https://github.com/AragurDEV) |[<img alt="bernhardreisenberger" src="https://avatars3.githubusercontent.com/u/5809300?v=4&s=117" width="117">](https://github.com/bernhardreisenberger) |[<img alt="yangdiangzb" src="https://avatars3.githubusercontent.com/u/16643665?v=4&s=117" width="117">](https://github.com/yangdiangzb) |[<img alt="quasilyte" src="https://avatars3.githubusercontent.com/u/6286655?v=4&s=117" width="117">](https://github.com/quasilyte) |[<img alt="jamesmaidment" src="https://avatars3.githubusercontent.com/u/2050324?v=4&s=117" width="117">](https://github.com/jamesmaidment) |[<img alt="johnrichardrinehart" src="https://avatars1.githubusercontent.com/u/6321578?v=4&s=117" width="117">](https://github.com/johnrichardrinehart) |
:---: |:---: |:---: |:---: |:---: |:---: |
[AragurDEV](https://github.com/AragurDEV) |[bernhardreisenberger](https://github.com/bernhardreisenberger) |[yangdiangzb](https://github.com/yangdiangzb) |[quasilyte](https://github.com/quasilyte) |[jamesmaidment](https://github.com/jamesmaidment) |[johnrichardrinehart](https://github.com/johnrichardrinehart) |

[<img alt="mathieu-aubin" src="https://avatars0.githubusercontent.com/u/15820228?v=4&s=117" width="117">](https://github.com/mathieu-aubin) |[<img alt="michalhisim" src="https://avatars0.githubusercontent.com/u/764249?v=4&s=117" width="117">](https://github.com/michalhisim) |[<img alt="pa-m" src="https://avatars2.githubusercontent.com/u/5503106?v=4&s=117" width="117">](https://github.com/pa-m) |[<img alt="paul-at-start" src="https://avatars2.githubusercontent.com/u/5486775?v=4&s=117" width="117">](https://github.com/paul-at-start) |[<img alt="liaoishere" src="https://avatars3.githubusercontent.com/u/6123425?v=4&s=117" width="117">](https://github.com/liaoishere) |[<img alt="ridvansumset" src="https://avatars2.githubusercontent.com/u/26631560?v=4&s=117" width="117">](https://github.com/ridvansumset) |
:---: |:---: |:---: |:---: |:---: |:---: |
[mathieu-aubin](https://github.com/mathieu-aubin) |[michalhisim](https://github.com/michalhisim) |[pa-m](https://github.com/pa-m) |[paul-at-start](https://github.com/paul-at-start) |[liaoishere](https://github.com/liaoishere) |[ridvansumset](https://github.com/ridvansumset) |

[<img alt="Jarema" src="https://avatars0.githubusercontent.com/u/7369771?v=4&s=117" width="117">](https://github.com/Jarema) |[<img alt="vkrol" src="https://avatars3.githubusercontent.com/u/153412?v=4&s=117" width="117">](https://github.com/vkrol) |[<img alt="haya14busa" src="https://avatars0.githubusercontent.com/u/3797062?v=4&s=117" width="117">](https://github.com/haya14busa) |
:---: |:---: |:---: |
[Jarema](https://github.com/Jarema) |[vkrol](https://github.com/vkrol) |[haya14busa](https://github.com/haya14busa) |

## License

MIT