4- capture with channels

prompter.go

package main

import (
	"bufio"
	"fmt"
	"os"
	"os/signal"
	"strconv"
	"syscall"
)

// scanStringUntilValid is a helper provided to get a string input from the
// terminal. It doesn't do any additional logic to simply retrieving the user
// input; it is only provided for consistency.
func scanStringUntilValid(s *bufio.Scanner, prefix string) string {
	fmt.Print(prefix)

	if !s.Scan() {
		return ""
	}
	return s.Text()

}

// scanIntUntilValid is a helper provided to get a float input from the terminal.
// It will prompt the user for a value until the value is a valid floating
// point number.
func scanFloatUntilValid(s *bufio.Scanner, prefix string) float64 {
	var valfloat float64
	var err error

	for {

		fmt.Print(prefix)
		if !s.Scan() {
			return 0
		}
		val := s.Text()
		if valfloat, err = strconv.ParseFloat(val, 64); err != nil {
			fmt.Println("Invalid number, please try again.")
			continue
		}
		return float64(valfloat)
	}

}

type Debt struct {
	Person   string
	Amount   float64
	Currency string
	Details  string
}

func CreateDebtPrompter(header string) Debt {
	if header != "" {
		fmt.Println(header)
	}
	s := bufio.NewScanner(os.Stdin)
	debt := Debt{}

	ops := []func(){
		func() {
			debt.Person = scanStringUntilValid(s, "person: ")
		},
		func() {
			debt.Amount = scanFloatUntilValid(s, "amount: ")
		},
		func() {
			debt.Currency = scanStringUntilValid(s, "currency: ")
		},
		func() {
			debt.Details = scanStringUntilValid(s, "details: ")
		},
	}

	for _, op := range ops {
		select {
		case <-c:
			fmt.Println("exited")
			os.Exit(1)
		default:
			op()
		}
	}

	return debt
}

var c = make(chan os.Signal, 1)

func main() {

	signal.Notify(c, syscall.SIGINT, syscall.SIGTERM)
	go func() {
		<-c
		fmt.Println("exited")
		os.Exit(1)
	}()

	debt := CreateDebtPrompter("")
	fmt.Println("debt created: %s", debt)
	return
}