magic_numbers

README

go-mnd - Magic number detector for Golang

A vet analyzer to detect magic numbers.

What is a magic number?
A magic number is a numeric literal that is not defined as a constant, but which may change, and therefore can be hard to update. It's considered a bad programming practice to use numbers directly in any source code without an explanation. It makes programs harder to read, understand, and maintain.

Project status

Install

Local

This analyzer requires Golang in version >= 1.12 because it's depends on the go/analysis API.

go get -u github.com/tommy-muehle/go-mnd/cmd/mnd

Github action

You can run go-mnd as a GitHub action as follows:

name: Example workflow
on:
  push:
    branches:
      - master
  pull_request:
    branches:
      - master
jobs:
  tests:
    runs-on: ubuntu-latest
    env:
      GO111MODULE: on
    steps:
      - name: Checkout Source
        uses: actions/checkout@v2
      - name: Run go-mnd
        uses: tommy-muehle/go-mnd@master
        with:
          args: ./...

Homebrew

To install with Homebrew, run:

brew tap tommy-muehle/tap && brew install tommy-muehle/tap/mnd

Docker

To get the latest available Docker image:

docker pull tommymuehle/go-mnd

Windows

On Windows download the latest release.

Usage

go vet -vettool $(which mnd) ./...

or directly

mnd ./...

or via Docker

docker run --rm -v "$PWD":/app -w /app tommymuehle/go-mnd:latest ./...

Options

The -checks option let's you define a comma separated list of checks.

The -ignored-numbers option let's you define a comma separated list of numbers to ignore.
For example: -ignored-numbers=1000,10_000,3.14159264

The -ignored-functions option let's you define a comma separated list of function name regexp patterns to exclude.
For example: -ignored-functions=math.*,http.StatusText

The -ignored-files option let's you define a comma separated list of filename regexp patterns to exclude.
For example: -ignored-files=magic_.*.go,.*_numbers.go

Checks

By default this detector analyses arguments, assigns, cases, conditions, operations and return statements.

• argument

t := http.StatusText(200)

• assign

c := &http.Client{
    Timeout: 5 * time.Second,
}

• case

switch x {
    case 3:
}

• condition

if x > 7 {
}

• operation

var x, y int
y = 10 * x

• return

return 3

Excludes

By default the numbers 0 and 1 as well as test files are excluded!

Further known excludes

The function "Date" in the "Time" package.

t := time.Date(2017, time.September, 26, 12, 13, 14, 0, time.UTC)

Additional custom excludes can be defined via option flag.

Development

Build

You can build the binary with:

make

Tests

You can run all unit tests using:

make test

And with coverage report:

make test-coverage

Docker image

You can also build locally the docker image by using the command:

make image

Stickers

Just drop me a message via Twitter DM or email if you want some go-mnd stickers for you or your Gopher usergroup.

License

The MIT License (MIT). Please see LICENSE for more information.

Documentation

Index

• Constants
• Variables
• type Checker

Constants

const Doc = `magic number detector`

Variables

var Analyzer = &analysis.Analyzer{
	Name:             "mnd",
	Doc:              Doc,
	Run:              run,
	Flags:            options(),
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	RunDespiteErrors: true,
}

Types

type Checker

type Checker interface {
	NodeFilter() []ast.Node
	Check(n ast.Node)
}