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cflag - wraps and extends Go flag build pertty CLI command

· 4 min read
inhere

cflag - wraps and extends Go flag build pertty CLI command

Use Go flag​

Go flag is a package built into Go, and it is very easy to build a command application using the flag package.

cflag/_example/rawflag.go
package main

import (
    "flag"
    "os"

    "github.com/gookit/goutil/cliutil"
    "github.com/gookit/goutil/dump"
)

var opts1 = struct {
    age  int
    name string
    str1 string
    lOpt string
}{}

// go run ./_example/rawflag.go
// go run ./cflag/_example/rawflag.go -h
func main() {
    c := flag.NewFlagSet("mycmd", flag.ContinueOnError)

    c.IntVar(&opts1.age, "age", 0, "this is a int option")
    c.StringVar(&opts1.name, "name", "", "this is a string option and required")
    c.StringVar(&opts1.str1, "str1", "def-val", "this is a string option with default value")
    c.StringVar(&opts1.lOpt, "long-opt", "", "this is a string option with shorts")

    err := c.Parse(os.Args[1:])
    if err != nil {
        if err != flag.ErrHelp {
            cliutil.Errorln("Error:", err.Error())
        }
        return
    }

    // after parse, do something
    handleFunc1()
}

func handleFunc1() {
    cliutil.Infoln("after parse, do something")

    dump.P(opts1)
}

Show help​

go run ./cflag/_example/rawflag.go -h

rawflag-help

Some problems​

It's a package built into Go, and it's very simple to use. But there are some problems:

  • Adding short options to options is not supported
  • Does not support parsing subsequent parameter information
  • Can't check if option is empty
  • Rendering help information is very rudimentary

Use cflag​

cflag - Wraps and extends go flag.FlagSet to build simple command line applications

  • As easy as Go flag to use
  • Supports auto-rendering of pretty help messages
  • Allows adding short options to flag options, and multiples
  • Allows binding named parameters
  • Allows setting arguments or options as required
  • Allows setting validators for arguments or options

Install​

go get github.com/gookit/goutil/cflag

Usage example​

cflag has the same binding option information as Go flag. At the same time, some additional information has been added, such as version, description, etc.

cflag/_example/cmd.go
package main

import (
    "os"

    "github.com/gookit/goutil/cflag"
    "github.com/gookit/goutil/cliutil"
)

var opts = struct {
    age  int
    name string
    str1 string
    lOpt string
    bol  bool
}{}

// go run ./_example/cmd.go
// go run ./cflag/_example/cmd.go -h
// go run ./cflag/_example/cmd.go --name inhere -a 12 --lo val ab cd
func main() {
    c := cflag.New(func(c *cflag.CFlags) {
        c.Desc = "this is a demo command"
        c.Version = "0.5.1"
    })
    c.IntVar(&opts.age, "age", 0, "this is a int option;;a")
    c.StringVar(&opts.name, "name", "", "this is a string option and required;true")
    c.StringVar(&opts.str1, "str1", "def-val", "this is a string option with default value;;s")
    c.StringVar(&opts.lOpt, "long-opt", "", "this is a string option with shorts;;lo")

    c.AddArg("arg1", "this is arg1", true, nil)
    c.AddArg("arg2", "this is arg2", true, nil)

    // add handle func
    c.Func = handleFunc

    c.MustParse(os.Args[1:])
}

func handleFunc(c *cflag.CFlags) error {
    cliutil.Magentaln("hello, this is command:", c.Name())
    cliutil.Infoln("after parse, do something ...")

    cliutil.Yellowln("option values:")
    cliutil.Infoln("opts.age =", opts.age)
    cliutil.Infoln("opts.name =", opts.name)
    cliutil.Infoln("opts.str1 =", opts.str1)
    cliutil.Infoln("opts.lOpt =", opts.lOpt)

    cliutil.Yellowln("argument values:")
    cliutil.Infoln("arg1 =", c.Arg("arg1").String())
    cliutil.Infoln("arg2 =", c.Arg("arg2").String())

    cliutil.Infoln("\nremain args =", c.RemainArgs())

    return nil
}

Set required and shortcuts​

Option can be set as required(required), and supports setting short option name.

TIPs: Implement required and shorts by extending usage that parses options

usage format​

  • Defatul: desc
  • Foramt 1: desc;required
  • Foramt 2: desc;required;shorts
  • required: A boolean string. Mark option is required
    • True: true,on,yes
    • False: false,off,no,''
  • shorts: Shortcut names for options, multiple values are allowed, separated by commas ,

Examples:

    // set option 'name' is required
    c.StringVar(&opts.name, "name", "", "this is a string option and required;true")
    // set option 'str1' shorts: s
    c.StringVar(&opts.str1, "str1", "def-val", "this is a string option with default value;;s")

Binding and get arguments​

Binding arguments

    c.AddArg("arg1", "this is arg1", true, nil)
    c.AddArg("arg2", "this is arg2", true, nil)

Get arguments by name

    cliutil.Infoln("arg1 =", c.Arg("arg1").String())
    cliutil.Infoln("arg2 =", c.Arg("arg2").Int())

Show help​

go run ./cflag/_example/cmd.go -h

Output:

cmd-help

Run command​

go run ./cflag/_example/cmd.go --name inhere -a 12 --lo val ab cd
go run ./cflag/_example/cmd.go --name inhere -a 12 --lo val ab cd de fg

Output:

cmd-run

required check​

go run ./cflag/_example/cmd.go -a 22
go run ./cflag/_example/cmd.go --name inhere

Output:

cmd-required.png

GitHub​