context

package main

import (
	"context"
	"fmt"

	contextutil "source.toby3d.me/toby3d/hacks/context"
)

func main() {
	type Username string

	var user Username = "toby3d"

	f := func(ctx context.Context) {
		// Retrieve typed value from parent context if exist.
		if name, exist := contextutil.Value[Username](ctx); exist {
			fmt.Printf("Hi, %s!\n", name)
		} else {
			fmt.Println("Access denied")
		}
	}

	ctx := context.Background()
	f(ctx)

	// Store some metadata in context.
	ctx = contextutil.WithValue(ctx, user)
	f(ctx)

}

Output:

Access denied
Hi, toby3d!