Pros of cli

• Simpler API with less boilerplate code
• Better suited for smaller projects or quick CLI prototypes
• Easier to understand and implement for beginners

Cons of cli

• Less feature-rich compared to Cobra
• Limited built-in support for flags and command nesting
• Fewer advanced features like shell completions or man page generation

Code Comparison

cli:

c := cli.NewCLI("app", "1.0.0")
c.Args = os.Args[1:]
c.Commands = map[string]cli.CommandFactory{
    "foo": fooCommandFactory,
}

Cobra:

var rootCmd = &cobra.Command{
    Use:   "app",
    Short: "A brief description of your application",
}
func Execute() {
    cobra.CheckErr(rootCmd.Execute())
}

Summary

cli is a lightweight and straightforward library for building command-line interfaces in Go. It's ideal for smaller projects or rapid prototyping. Cobra, on the other hand, offers a more comprehensive set of features and is better suited for larger, more complex CLI applications. Cobra provides built-in support for nested commands, flags, and advanced features like shell completions and man page generation. While cli has a simpler API and is easier to get started with, it may lack some of the advanced functionality that Cobra offers out of the box.

Pros of Kingpin

• More concise API, requiring less boilerplate code
• Built-in support for environment variables
• Easier to define mutually exclusive flags

Cons of Kingpin

• Less active development and community support
• Fewer advanced features compared to Cobra (e.g., shell completions)
• Limited built-in documentation generation capabilities

Code Comparison

Kingpin:

app := kingpin.New("chat", "A command-line chat application")
send := app.Command("send", "Send a message")
message := send.Arg("message", "Message to send").Required().String()

Cobra:

var rootCmd = &cobra.Command{
    Use:   "chat",
    Short: "A command-line chat application",
}
var sendCmd = &cobra.Command{
    Use:   "send [message]",
    Short: "Send a message",
    Args:  cobra.ExactArgs(1),
}

Both Cobra and Kingpin are popular command-line interface (CLI) libraries for Go. Cobra is more widely used and offers a richer feature set, including automatic help generation and shell completions. Kingpin, on the other hand, provides a more streamlined API and built-in support for environment variables. The choice between the two depends on the specific requirements of your project and personal preference for API style.

Pros of go-flags

• More flexible tag-based approach for defining flags
• Supports automatic generation of man pages
• Allows for more complex flag types and custom parsing

Cons of go-flags

• Less intuitive for newcomers compared to Cobra's command-based structure
• Lacks built-in support for persistent flags across subcommands
• Documentation is not as extensive as Cobra's

Code Comparison

go-flags example:

type Options struct {
    Verbose []bool `short:"v" long:"verbose" description:"Show verbose debug information"`
    Name    string `short:"n" long:"name" description:"A name" required:"true"`
}

var opts Options
_, err := flags.Parse(&opts)

Cobra example:

var rootCmd = &cobra.Command{
    Use:   "app",
    Short: "A brief description of your application",
    Run: func(cmd *cobra.Command, args []string) {
        // Your logic here
    },
}

rootCmd.PersistentFlags().BoolP("verbose", "v", false, "verbose output")
rootCmd.Flags().StringP("name", "n", "", "A name")
rootCmd.MarkFlagRequired("name")

Both libraries offer powerful CLI parsing capabilities, but Cobra provides a more structured approach with its command-based system, while go-flags offers more flexibility in flag definition through struct tags.

Pros of docopt.go

• Simpler syntax for defining command-line interfaces
• Automatically generates help messages based on the usage pattern
• Supports a wide range of argument types and patterns out of the box

Cons of docopt.go

• Less flexible for complex command structures
• Limited built-in support for subcommands
• Fewer additional features compared to Cobra (e.g., shell completions, man page generation)

Code Comparison

docopt.go:

usage := `Naval Fate.

Usage:
  naval_fate ship new <name>...
  naval_fate ship <name> move <x> <y> [--speed=<kn>]
  naval_fate ship shoot <x> <y>
  naval_fate mine (set|remove) <x> <y> [--moored|--drifting]
  naval_fate -h | --help
  naval_fate --version`

arguments, _ := docopt.Parse(usage, nil, true, "Naval Fate 2.0", false)

Cobra:

var rootCmd = &cobra.Command{
  Use:   "naval_fate",
  Short: "A brief description of your application",
  Long: `A longer description...`,
}

func init() {
  rootCmd.AddCommand(shipCmd)
  rootCmd.AddCommand(mineCmd)
}

Pros of go-arg

• Simpler and more lightweight, with a focus on ease of use
• Automatically generates help text based on struct tags
• Supports nested structs for organizing complex command-line options

Cons of go-arg

• Less feature-rich compared to Cobra's extensive functionality
• Limited support for subcommands and complex command hierarchies
• Smaller community and ecosystem around the project

Code Comparison

go-arg:

type Args struct {
    Foo string `arg:"required,-f" help:"foo option"`
    Bar int
}

func main() {
    var args Args
    arg.MustParse(&args)
}

Cobra:

var rootCmd = &cobra.Command{
    Use:   "app",
    Short: "A brief description of your application",
    Run: func(cmd *cobra.Command, args []string) {
        // Your logic here
    },
}

func main() {
    rootCmd.Execute()
}

Both go-arg and Cobra are popular command-line argument parsing libraries for Go. go-arg offers a simpler approach, using struct tags to define arguments and automatically generate help text. It's lightweight and easy to use for straightforward CLI applications. Cobra, on the other hand, provides a more comprehensive solution with support for complex command hierarchies, persistent flags, and a rich set of features. It's better suited for larger applications with multiple subcommands and advanced CLI requirements. The choice between the two depends on the complexity of your application and your specific needs.