Go Cheat Sheet Page 2023-07-08 https://www.andy-pearce.com ...

Go Cheat Sheet

Page 1 of 6

Last modi ed: 2023-09-30

? Copyright 2023 Andy Peace --

Distributed under MIT license --

Tooling

go env go help environment

Show all Go settings Show purpose of all Go settings

Development

go run go get @ go list -m all go mod why -m go clean -modcache gofmt -d -w -r `abc -> xyz' go doc go doc -all go doc -src

Runs executable in directory Fetch dependency optionally at version Show all dependencies Why does this module depend on ? Clean the module cache Replace abc with xyz Display summary documentation for Display full documentation for Display source code for

Testing

go test go test /... go test -race ... go test -count= ... go clean -testcache go test -v -run= ... go test -short ... go test -failfast ... go test -fuzz ... go test -fuzz -fuzztime= ... go test -cover ... go test -coverprofile= go test -covermode=count ... go tool cover -html= go tool cover -func=

Runs all tests in directory Runs all tests in and subdirectories Run tests with data race detector Bypass test cache and run tests times Clean up all cached test results Run all tests matching regular expression Skips tests lagged as long-running Stop running tests on rst failure Run any de ned fuzz tests until a failure is found or aborted Run any de ned fuzz tests until a failure is found or expires Show code coverage summary Generate coverage metrics in output le Additionally capture the number of times each line is hit Show report from recorded coverage metrics in browser Show report from recorded coverage metrics in terminal

Latest version: Go logo copyright 2018 The Go Authors, licensed under Creative Commons Attribution 4.0.

if

i

f

i if f f

if

Go Cheat Sheet

Page 2 of 6

Last modi ed: 2023-07-08

? Copyright 2023 Andy Peace --

Distributed under MIT license --

Tidying Up

go fmt ./... go vet go mod tidy go mod verify

Reformat this and all subdirectories Run static code analysis on le or directory Remove unused dependencies Verify that dependencies are still clean

Building

go build -o=

Build package in optionally placing output in

go build -a ...

Bypass cache and rebuild all packages

go clean -cache

Clean entire build cache

GOOS=linux GOARCH=amd64 go build ... Specify operating system and architecture for cross-compilation

go tool dist list

List all valid OS/arch targets for this compiler

go build -gcflags="" ...

Pass to the compiler for packages listed on command-line

... -gcflags="=" ...

Pass to the compiler for all packages matching

go build -ldflags="" ...

Pass to the linker

Ongoing Maintenance

go test -bench= ... -benchmem ... -benchtime= ... -count= ... -cpu= go test -cpuprofile= go test -memprofile= go test -blockprofile= go test -mutexprofile= go tool pprof ... -top -functions ... ... -top -lines ... ... -http localhost: ... go list -u -m all go get @ go mod tidy && go test all

Runs tests and benchmarks from Shows memory allocations for each iteration as well as execution time Sets the threshold time (e.g. 5s) or number of iterations (e.g. 500x) Repeats each benchmark times in sequence Runs each benchmark with GOMAXPROCS at each value in list Run tests outputting CPU time pro ling data to Run tests outputting memory allocation pro ling data to Run tests outputting blocking call pro ling data to Run tests outputting mutex contention pro ling data to Run interactive CLI on executable with pro ling data Show top users at granularity of functions Show top users at granularity of source code lines Start interactive web interface on and open a browser on it For each dependency, show current version and upstream latest Also used to update existing dependency version Good idea to do this a ter updating dependencies

Latest version: Go logo copyright 2018 The Go Authors, licensed under Creative Commons Attribution 4.0.

if

i

f if

i

f

if

if

f

if

Go Cheat Sheet

Page 3 of 6

Last modi ed: 2023-07-08

? Copyright 2023 Andy Peace --

Distributed under MIT license --

Scalar Types

bool (true / false)

uint uint8 uint16 uint32 uint64

string

int int8 int16 int32 int64

float32 complex64

float64 complex128

uintptr rune (int32) byte (uint8)

Pointer & Channel Types

var ptr *int

var value int = 99

ptr = &value

value = *ptr

unbuffered := make(chan int)

buffered := make(chan int, 100)

chan 0 { ... i -= 1

}

for { ... break

}

Functions & Closures

for i := 0; i < 10; i++ { ...

}

for i, val := range items { ...

}

func name(arg1 int, arg2 string) int { ... return 123

func name(arg string) (string, error) { ... return "", errors.New("Foo")

func name(arg int, more ...string) { for i, value := range more { ... } anotherFunc(arg, more...)

}

Panic, Defer & Recover

func name() (someVar int) { someVar = 123 return

}

func ticketMachine(start int) func() int { return func() int { start++ return start }

}

panic(value)

func someFunc(arg int) { ... } Func otherFunc() {

defer someFunc(123) ... }

Predeclared Identi ers

func name() {

defer func() { if r := recover(); r != nil { ... }

}() ...

}

any bool byte comparable error complex64 complex128 float32 float64 int int8 int16 int32 int64 rune string uint uint8 uint16 uint32 uint64 uintptr

true false iota nil

append cap close complex copy delete imag len make new panic print println real recover

Latest version: Go logo copyright 2018 The Go Authors, licensed under Creative Commons Attribution 4.0.

i

f

if

Go Cheat Sheet

Page 5 of 6

Last modi ed: 2023-07-08

? Copyright 2023 Andy Peace --

Distributed under MIT license --

Methods

type Point struct { x, y float64

} func (p *Point) move(dx, dy float64) {

p.x += dx p.y += dy }

Value type T T *T *T

Receiver type T *T T *T

Callable?

Interfaces

type Shape interface { area() float64 translate(x, y float64)

}

func f(s Shape) float64 { s.translate(1.0, 5.0) return s.area()

}

type Cornered interface { Shape numCorners() int

}

All types implement the empty interface interface{} type SignedInt interface { ~int | ~int8 | ~int16 | ~int32 | ~int64

The ~ means "same underlying type", without it's an exact match }

Generics

type List[T any] struct { ...

}

func (node *List[T]) insertAfter(item T) *List[T] { ...

}

func find[T comparable](n T, h []T) int { ...

}

func newList[T any](item T) *List[T] { return &List[T]{item, nil, nil}

}

Go Routines & Channels

func consumer(c ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download