Linter
Automatically analyze source code for potential errors, stylistic issues, and violations of coding conventions
About me
var Me = Developer{
Name: "Manuel Doncel Martos",
Skills: [][]string{
{"☕Java", "Spring Boot"},
{"🦫Go", "🐍Python"},
{"Kubernetes", "Docker"},
},
Interests: []string {
"Open Source",
"Domain Driven Design",
"⚽Football",
},
}
Agenda
- Golangci-lint in a nutshell (~5m)
- Create your first linter (~10m)
- My experience creating linters (~5m)
- Create custom plugin (~15m)
- Q/A (~5m)
golangci-lint
Golangci-lint is a fast linters runner for Go.
- Widely used.
- More than 100 linters.
- Run linters.
- Run formatters.
@startuml
skinparam backgroundColor transparent
skinparam monochrome reverse
!option handwritten true
revive - [golangci-lint]
gofmt - [golangci-lint]
gofumpt - [golangci-lint]
gci - [golangci-lint]
... - [golangci-lint]
funcorder -- [golangci-lint]
embeddedstructfieldcheck -- [golangci-lint]
@enduml
Example configurations
version: 2
Others:
Tools Analyzer
Package golang.org/x/tools
- Token
- Analyzer
- Pass
- Diagnosis
AST Parser
@startwbs
skinparam backgroundColor transparent
skinparam monochrome reverse
!option handwritten true
* ast.File
** ast.GenDecl
*** ast.ImportSpec
**** ast.BasicLit
** ast.GenDecl
*** ast.ValueSpec
**** ast.Ident
**** ast.BasicLit
** ast.GenDecl
*** ast.TypeSpec
*** ast.StructType
**** ast.FieldList
***** ast.Field
***** ast.Field
** ast.FuncDecl
*** ast.FuncType
*** ast.FieldList
**** ast.Field
**** ast.Field
** ...
@endwbs
File to test: here
Create your first linter
Prefix unexported globals with
❌ Bad
const myConstant = "myConstant"
const errNotFound = "not found"
✅ Good
const _myConstant = "myConstant"
const errNotFound = "not found"
- Identify
- Suggest fix
Let's
🧐 My linters
❌ Bad
// ❌ constructor before
// struct declaration
func NewMyStruct() *MyStruct {
return &MyStruct{}
}
type MyStruct struct {
Name string
}
// ❌ unexported method
// placed before exported method
func (m MyStruct) lenName() int {
return len(m.Name)
}
func (m MyStruct) GetName() string {
return m.Name
}
...
type Client struct {
version int
http.Client
}
✅ Good
type MyStruct struct {
Name string
}
// ✅ constructor after
// struct declaration and
// before methods
func NewMyStruct() *MyStruct {
return &MyStruct{}
}
// ✅ exported methods before
// unexported methods
func (m MyStruct) GetName() string {
return m.Name
}
func (m MyStruct) lenName() int {
return len(m.Name)
}
...
❌ Bad
type Client struct {
version int
http.Client
}
✅ Good
type Client struct {
http.Client
version int
}
Create custom plugin
More info: Module Plugin
Example: Custom Plugin
Let's
Q/A
