odin

A note to readers:
I did my best to make this readme as comprehensive as possible but I strongly suggest reading the godocs detailed information on the internals of odin.

---

Installation | Usage | Examples | Contributing | In the Wild

A go-lang library to help build self documenting command line applications.

odin currently supports:

• Required Parameters
• Typed Flag/Option Parsing
• Flag Aliasing
• SubCommand DSL for creating complex CLI utils

Installation

get the package with:

go get github.com/jwaldrip/odin/cli

import it with:

import "github.com/jwaldrip/odin/cli"

or using a a package manager like Goop:

# Goopfile
github.com/jwaldrip/odin #v1.4.0

Usage

Creating a new CLI | Flags | Required Parameters | Freeform Parameters | Sub Commands | Self Documentation

Creating a new CLI

cli.New(version string, description string, fn func(), params...)

Flags

Flags are optional parameters that can be specifed when running the command.

$ cmd --flag=value -g

Defining

Flags support a number of different types and can be defined by using a basic definition or pointer definition.

Basic Definitions are in the format of:

DefineTypeFlag(name string, defaultValue typedValue, usage string)

Pointer Definitions are in the format of:

var ptr TYPE
DefineTypeFlagVar(ptr, name string, defaultValue typedValue, usage string)

Supported Value Types

Value Type	Basic Definition Method	Pointer Defintion Method
bool	DefineBoolFlag	DefineBoolFlagVar
float64	DefineFloat64Flag	DefineFloat64FlagVar
int	DefineIntFlag	DefineIntFlagVar
int64	DefineInt64Flag	DefineInt64FlagVar
string	DefineStringFlag	DefineStringFlagVar
time.Duration	DefineDurationFlag	DefineDurationFlagVar
uint	DefineUintFlag	DefineUintFlagVar
uint64	DefineUint64Flag	DefineUint64FlagVar

Flags also support aliases: aliases are always defined as a rune to limit them to one character.

AliasFlag(alias rune, flagName string)

Example

package main

import (
	"fmt"

	"github.com/jwaldrip/odin/cli"
)

// CLI is the odin CLI
var app = cli.New("0.0.1", "my cli", func(c cli.Command){
	if c.Flag("gopher").Get() == true {
		fmt.Println("IS JUST GOPHERTASTIC!!!")
	} else {
		fmt.Println("Is pretty dandy")
	}
})

func init(){
	app.DefineBoolFlag("gopher", false, "is it gophertastic?")
	app.AliasFlag('g', "gopher")
}

func main(){
	app.Start()
}

$ mycli
Is pretty dandy

$ mycli --gopher
IS JUST GOPHERTASTIC!!!

$ mycli -g
IS JUST GOPHERTASTIC!!!

Required Parameters

Defining

Commands can specify parameters that they require in the order they are passed. All parameter arguments are treated as string values.

They can be defined at CLI creation...

cli.New(version string, description string, fn func(Command), params ...string)

or at a later time...

app.DefineParams(params ...string)

Accessing

Parameters can be accessed invidually...

	cmd.Param(name string) Value

or as a ValueMap where the name is the string key of the map.

	cmd.Params() ValueMap

Freeform Parameters

Free form parameters are any parameters that remain after all parsing has completed.

To access them you can call them by their order...

cmd.Arg(0) Value

or just by getting them all as a slice

cmd.Args() ValueList

Sub Commands

Sub commands can be defined in order to create chainable, complex command line utlilities.

Defining

Sub commands have all the same defintion methods as the root level command, with one caveat; they have a Parent() method that can be used to fetch parameters and flags from further up the command chain.

mycli.DefineSubCommand(name string, description string, fn func(Command), params ...string)

Accessing Params + Flags

You would access the sub-command's flags and params just as you would a normal root level CLI.

cmd.Param("name")
cmd.Flag("name")

To access a parent commands just call:

cmd.Parent().Param("name")
cmd.Parent().Flag("name")

Flag Inheritence

In addition to accesing the parent params via the Parent() you can instruct a sub command to inherit a flag from its parent.

example:

package main

import (
   "fmt"
	"github.com/jwaldrip/odin"
)

var app = cli.New("0.0.1", "sample command", func(Command){})

func init(){
	app.DefineStringFlag("user", "", "the user")
	subcmd := app.DefineSubCommand("action", "perform an action", func(c cli.Command){
		fmt.Println("the user is:", c.Flag("user"))
		fmt.Println("the action is:", c.Param("actionName"))
	})
	subcmd.DefineParams("actionName")
	subcmd.InheritFlag("user")
}

func main(){
	app.Start()
}

$ mycmd --user=jason action hello
the user is: jason
the action is: hello

Output

Helpers

Output is possible directly on the CLI and is prefered over using fmt. Available commands map to their fmt counterparts.

method	description
ErrPrint(a ...interface{})	Prints to the err output.
ErrPrintf(format string, a ...interface{})	Prints formatted to the err output.
ErrPrintln(a ...interface{})	Prints a line to the err output.
Print(a ...interface{})	Prints to the std output.
Printf(format string, a ...interface{})	Prints formatted to the std output.
Println(a ...interface{})	Prints a line to the std output.

package main

import "github.com/jwaldrip/odin/cli"

app := cli.New("1.0.0", "my app", func(c cli.Command){
  c.Println("hello world")
  c.ErrPrintln("There was an error")
} 

Custom Output

Any io.Writer can be used as an output

outbuffer := bytes.NewBufferString("")
errbuffer := bytes.NewBufferString("")
app.SetStdOut(outbuffer)
app.SetStdErr(errbuffer)

Self Documentation

Usage

Documentation is auto generated for all commands (main and sub). By Default a help flag --help and alias -h are defined on each command (unless overridden) to display usage to the end user.

Auto generated documentation for ./examples/greet-with:

$ greet-with -h
Usage:
  greet-with [options...] <greeting> <command> [arg...]

a simple tool to greet with

Options:
  -c, --color="blue"  # color the output (red, blue, green)
  -h, --help          # show help and exit
  -l, --loudly        # say loudly
  -v, --version       # show version and exit

Commands:
  to     greet a person

Version

By Default a version flag --version and alias -v are defined on the main command (unless overridden), which will display the version specified when creating a new CLI.

Version for ./examples/greet-with:

$ greet-with -v
greet-with 1.0.0

Examples

Example CLIs can be found in ./examples

In the wild

Here are some tools using Odin in the wild. Have your own you would like to plug? Submit a pull request!

• nitrous-io/tug
• jwaldrip/git-get
• Sam-Izdat/pogo

Todo

• Bash Completion
• Zsh Completion
• CLI Bootstrapping
• Param Inheritence

Contributing

See CONTRIBUTING for details on how to contribute.