Go Development

Oct 22, 2024

Checking Go Installation

go version

This command checks if Go is installed and displays the version and architecture.

Modules and Package Management

Initialize a new Go module

go mod init sample-go

Downloads the package into Go’s module cache (not your project folder).
Updates go.mod and go.sum with the package version.
The cache is stored in:
- Linux/macOS: ~/go/pkg/mod
- Windows: %USERPROFILE%/go/pkg/mod

How this differs from Python

Feature	Python (pip)	Go (go get)
Install location	Virtual environment or system site-packages	Shared module cache
Per-project isolation	Achieved via venv/conda	Achieved via go.mod version tracking
Package retrieval	From PyPI	From VCS (GitHub, etc.) or module proxy
Version control	requirements.txt	go.mod + go.sum
Editable install	pip install -e .	No direct equivalent; use local replace directive

Exported vs Unexported Fields

In Go, only exported fields (starting with an uppercase letter) are accessible outside the package and eligible for reflection-based operations (e.g., JSON unmarshalling).

type Person struct {
    Name string // Exported
    age  int    // Unexported
}

var p Person
json.Unmarshal([]byte(`{"Name":"Alice","age":30}`), &p)
// p.Name = "Alice"
// p.age = 0  (unchanged because it's unexported)

Tips: Use JSON struct tags to control field names:

Name string `json:"full_name"`

Generics and Type Parameters

Functions can have type parameters

func PrintSlice[T any](s []T) {
    for _, v := range s {
        fmt.Println(v)
    }
}

Methods cannot have their own type parameters

❌This will fail

func (p Person) DoSomething[T any](value T) {}

Error:

method must have no type parameters

✅ Instead, put type parameters on the type:

type Box[T any] struct {
    value T
}

func (b Box[T]) Get() T {
    return b.value
}

Miscellaneous Useful Commands

Tidy up dependencies

go mod tidy

Removes unused dependencies and fetches any missing ones.

List all dependencies

go list -m all

Cache location

go env GOMODCACHE