decli

De(clarative) CLI

Purpose of DeCLI is to simplify parsing complex CLI arguments and defining rich CLI tools with minimal amount of required code.

DeCLI builds on top of cli. It relies heavily on defining CLI parameters as field tags in Golang structs instead of programmatically defining the arguments using Go code.

Why should I use it?

DeCLI enables you to write more concise code and will add type safety to your arguments.

As an illustration, here's a hello world example of a DeCLI:

package main

import (
    "fmt"
    "os"

    "github.com/draganm/decli"
)

type App struct {
    FirstName string `name:"first-name" usage:"your first name" aliases:"fn"`
    LastName  string `name:"last-name" usage:"your last name" aliases:"ln"`
    Age       int    `name:"age" usage:"your age"`
}

func (a *App) Run([]string) error {
    fmt.Printf("Hello %s %s (%d)\n", a.FirstName, a.LastName, a.Age)
    return nil
}

func main() {
    decli.RunAndFinish(&App{FirstName: "John", LastName: "Doe", Age: -1}, os.Args)
}

as opposed to using raw cli:

package main

import (
    "fmt"
    "log"
    "os"

    "github.com/urfave/cli/v2"
)

func main() {
    app := cli.App{
        Flags: []cli.Flag{
            &cli.StringFlag{
                Name:    "first-name",
                Usage:   "your first name",
                Aliases: []string{"fn"},
                Value:   "John",
            },
            &cli.StringFlag{
                Name:    "last-name",
                Usage:   "your last name",
                Aliases: []string{"ln"},
                Value:   "Doe",
            },
            &cli.IntFlag{
                Name:  "age",
                Usage: "your age",
                Value: -1,
            },
        },
        Action: func(c *cli.Context) error {
            fmt.Printf("Hello %s %s (%d)\n", c.String("first-name"), c.String("last-name"), c.Int("age"))
            return nil
        },
    }

    err := app.Run(os.Args)
    if err != nil {
        log.Fatalf("error: %s\n", err.Error())
    }
}

Both sources do the same, DeCLI version has almost the half of lines of code.