CLI Package

The cli package is a powerful Go library for building user-friendly command-line interfaces (CLIs). It provides an intuitive API for creating and managing complex command structures, parsing command-line arguments, and providing helpful error messages and usage information.

Features

Simple API for building nested command structures
Automatic argument parsing and validation
Built-in support for command flags and options
Automatic generation of usage and help information
Follows Go best practices for command-line application development

Core Concepts

Commands

Commands are the basic building blocks of your CLI application. Each command can have a name, description, handler function, and subcommands.

Flags

Flags allow you to define parameters that can be passed to your commands. The package supports both short and long flag names, default values, and usage descriptions.

Context

The context provides access to the parsed command-line arguments and flags within command handlers.

Usage Examples

Basic Command

package main

import (
    "fmt"
    "log"
    "oss.nandlabs.io/golly/cli"
)

func main() {
    app := cli.NewCLI()

    gollyCmd := &cli.Command{
        Name:        "welcome",
        Description: "Welcome command",
        Handler: func(ctx *cli.Context) error {
            fmt.Println("welcome to golly!")
            return nil
        },
    }

    app.AddCommand(gollyCmd)

    if err := app.Execute(); err != nil {
        log.Fatal(err)
    }
}

Nested Commands

package main

import (
    "fmt"
    "log"
    "oss.nandlabs.io/golly/cli"
)

func main() {
    app := cli.NewCLI()

    welcomeCmd := &cli.Command{
        Name: "welcome",
        Description: "Welcome to golly",
        Handler: func(ctx *cli.Context) error {
            fmt.Println("welcome to golly")
            return nil
        },
        SubCommands: map[string]*cli.Command{
            "home": {
                Name:        "home",
                Description: "welcome home",
                Handler: func(ctx *cli.Context) error {
                    fmt.Println("welcome home")
                    return nil
                },
            },
            "office": {
                Name:        "office",
                Description: "welcome to the office",
                Handler: func(ctx *cli.Context) error {
                    fmt.Println("welcome office")
                    return nil
                },
            },
        },
    }

    app.AddCommand(welcomeCmd)

    if err := app.Execute(); err != nil {
        log.Fatal(err)
    }
}

Working with Flags

package main

import (
    "fmt"
    "log"
    "oss.nandlabs.io/golly/cli"
)

func main() {
    app := cli.NewCLI()

    server := &cli.Command{
        Name:        "server",
        Description: "Server command",
        Handler: func(ctx *cli.Context) error {
            region, _ := ctx.GetFlag("region")
            fmt.Printf("IN REGION, %s\n", region)
            return nil
        },
        Flags: []cli.Flag{
            {
                Name:    "region",
                Aliases: []string{"r"},
                Usage:   "Provide region",
                Default: "",
            },
        },
        SubCommands: map[string]*cli.Command{
            "create": {
                Name:        "create",
                Description: "create server",
                Handler: func(ctx *cli.Context) error {
                    typ, _ := ctx.GetFlag("type")
                    fmt.Printf("SERVER TYPE %s\n", typ)
                    return nil
                },
                Flags: []cli.Flag{
                    {
                        Name:    "type",
                        Aliases: []string{"t"},
                        Usage:   "server type",
                        Default: "",
                    },
                },
            },
        },
    }

    app.AddCommand(server)

    if err := app.Execute(); err != nil {
        log.Fatal(err)
    }
}

Installation

go get oss.nandlabs.io/golly/cli

Assertion Package Clients Package