advanceTopics.md

Advanced Go Topics

1. Interfaces and Polymorphism

Go uses interfaces for achieving polymorphism, allowing different types to implement the same behavior without explicit inheritance.

type Speaker interface {
    Speak() string
}

type Dog struct{}
func (d Dog) Speak() string { return "Woof!" }

type Cat struct{}
func (c Cat) Speak() string { return "Meow!" }

func main() {
    var s Speaker
    s = Dog{}
    fmt.Println(s.Speak()) // Output: Woof!
    s = Cat{}
    fmt.Println(s.Speak()) // Output: Meow!
}

2. Dependency Management

Go modules (go mod) help manage dependencies efficiently.

go mod init myapp
go get github.com/gin-gonic/gin

3. Unit Testing

Testing in Go is performed using the testing package.

import "testing"
func TestSum(t *testing.T) {
    result := sum(1, 2, 3)
    if result != 6 {
        t.Errorf("Expected 6 but got %d", result)
    }
}

4. Logging and Debugging

Use the log package for logging messages and errors.

import "log"
func main() {
    log.Println("This is a log message")
}

5. Networking in Go

HTTP Server

import (
    "fmt"
    "net/http"
)

func handler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, "Hello, World!")
}

func main() {
    http.HandleFunc("/", handler)
    http.ListenAndServe(":8080", nil)
}

HTTP Client

import (
    "fmt"
    "io/ioutil"
    "net/http"
)

func main() {
    resp, _ := http.Get("https://jsonplaceholder.typicode.com/todos/1")
    defer resp.Body.Close()
    body, _ := ioutil.ReadAll(resp.Body)
    fmt.Println(string(body))
}

6. Database Interaction

Connecting to PostgreSQL

import (
    "database/sql"
    _ "github.com/lib/pq"
)

func main() {
    connStr := "user=username dbname=mydb sslmode=disable"
    db, _ := sql.Open("postgres", connStr)
    defer db.Close()
}

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