从源代码来看cmd包进行了一些初始化操作并提供了Execute接口。十分简单，其中viper是cobra集成的配置文件读取的库，这里不需要使用，我们可以注释掉（不注释可能生成的应用程序很大约10M，这里没哟用到最好是注释掉）。cobra的所有命令都是通过cobra.Command这个结构体实现的。为了实现demo功能，显然我们需要修改RootCmd。修改后的代码如下：
// Copyright © 2016 NAME HERE <EMAIL ADDRESS>
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package cmd
import (
"fmt"
"os"
"github.com/spf13/cobra"
// "github.com/spf13/viper"
"demo/imp"
)
//var cfgFile string
var name string
var age int
// RootCmd represents the base command when called without any subcommands
var RootCmd = &cobra.Command{
Use: "demo",
Short: "A test demo",
Long: `Demo is a test appcation for print things`,
// Uncomment the following line if your bare application
// has an action associated with it:
Run: func(cmd *cobra.Command, args []string) {
if len(name) == 0 {
cmd.Help()
return
}
imp.Show(name, age)
},
}
// Execute adds all child commands to the root command sets flags appropriately.
// This is called by main.main(). It only needs to happen once to the rootCmd.
func Execute() {
if err := RootCmd.Execute(); err != nil {
fmt.Println(err)
os.Exit(-1)
}
}
func init() {
// cobra.OnInitialize(initConfig)
// Here you will define your flags and configuration settings.
// Cobra supports Persistent Flags, which, if defined here,
// will be global for your application.
// RootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.demo.yaml)")
// Cobra also supports local flags, which will only run
// when this action is called directly.
// RootCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
RootCmd.Flags().StringVarP(&name, "name", "n", "", "person's name")
RootCmd.Flags().IntVarP(&age, "age", "a", 0, "person's age")
}
// initConfig reads in config file and ENV variables if set.
//func initConfig() {
// if cfgFile != "" { // enable ability to specify config file via flag
// viper.SetConfigFile(cfgFile)
// }
// viper.SetConfigName(".demo") // name of config file (without extension)
// viper.AddConfigPath("$HOME") // adding home directory as first search path
// viper.AutomaticEnv() // read in environment variables that match
// // If a config file is found, read it in.
// if err := viper.ReadInConfig(); err == nil {
// fmt.Println("Using config file:", viper.ConfigFileUsed())
// }
//}
