converter/cmd/root.go

package cmd

import (
	"fmt"
	"os"
	"strconv"

	u "github.com/bcicen/go-units"
	"github.com/spf13/cobra"
)

var (
	from    string
	to      string
	rootCmd = &cobra.Command{
		Use:   "converter",
		Short: "A brief description of your application",
		Long: `A longer description that spans multiple lines and likely contains
examples and usage of using your application. For example:

Cobra is a CLI library for Go that empowers applications.
This application is a tool to generate the needed files
to quickly create a Cobra application.`,
		Run: func(cmd *cobra.Command, args []string) {
			in, err := strconv.ParseFloat(args[0], 64)
			if err != nil {
				fmt.Println(err.Error())
				return
			}
			fromVal, err := u.Find(cmd.Flag("from").Value.String())
			if err != nil {
				fmt.Println(err.Error())
				return
			}
			toVal, err := u.Find(cmd.Flag("to").Value.String())
			if err != nil {
				fmt.Println(err.Error())
				return
			}
			val := u.NewValue(in, fromVal)
			out, err := val.Convert(toVal)
			if err != nil {
				fmt.Println(err.Error())
				return
			}
			fmt.Println(out.String())
		},
	}
)

func Execute() {
	err := rootCmd.Execute()
	if err != nil {
		os.Exit(1)
	}
}

func init() {
	rootCmd.PersistentFlags().StringVarP(&from, "from", "f", "c", "unit system to convert from")
	rootCmd.PersistentFlags().StringVarP(&to, "to", "t", "f", "unit system to convert to")
}