Functional options

main.go

package main

import (
	"fmt"
	"time"
)

type Config struct {
	Secure  bool
	Timeout time.Duration
	Host    string
	Port    int
}

func NewConfig(options ...func(*Config)) *Config {
	c := &Config{}
	for _, option := range options {
		option(c)
	}
	return c
}

func main() {
	host := func(c *Config) {
		c.Host = "addr"
	}

	port := func(c *Config) {
		c.Port = 5
	}

	timeout := func(c *Config) {
		c.Timeout = 15 * time.Second
	}

	cfg := NewConfig(host, port, timeout)

	fmt.Printf("%+v", cfg)
}