cli

Package cli

import (
	"github.com/titpetric/cli"
}

CLI package

This package contains the implementation for a minimal opinionated flags framework similar to spf13/cobra. It all centers around the cli.Command type but provides less functionality.

To create a new CLI application:

app := cli.NewApp("mig")
app.AddCommand("version", version.Name, version.New)

	if err := app.Run(); err != nil {
	        return err
	}

The version.New is a func() *cli.Command.

The Command type defines Name and Title as strings, equivallent to cobra Command.Use (Name) and Command.Long (Title). There is no equivalent of Command.Short.

The API choices are different, cobra's AddCommand took a command, and the command type was passed into Run().

The cli package creates a CommandInfo with AddCommand, and then calls the constructor of the *Command type. The type must have Run filled, and can implement Bind(*pflag.FlagSet) to read in CLI flags.

The Run function is context aware, supporting observability.

Types

// App is the cli entrypoint.
type App struct {
	Name	string

	commands	map[string]CommandInfo
}

// Command and CommandInfo types for CLI command handling.
type (
	// Command is an individual command
	Command	struct {
		Name, Title	string

		Bind	func(*flag.FlagSet)
		Run	func(context.Context, []string) error
	}

	// CommandInfo is the constructor info for a command
	CommandInfo	struct {
		Name	string
		Title	string
		New	func() *Command
	}
)

Vars

// Flag variable binding functions from spf13/pflag.
var (
	BoolVar		= flag.BoolVar
	DurationVar	= flag.DurationVar
	Int64Var	= flag.Int64Var
	IntVar		= flag.IntVar
	StringVar	= flag.StringVar
	Uint64Var	= flag.Uint64Var
	UintVar		= flag.UintVar
	StringSliceVar	= flag.StringSliceVar

	BoolVarP	= flag.BoolVarP
	DurationVarP	= flag.DurationVarP
	Int64VarP	= flag.Int64VarP
	IntVarP		= flag.IntVarP
	StringVarP	= flag.StringVarP
	Uint64VarP	= flag.Uint64VarP
	UintVarP	= flag.UintVarP
	StringSliceVarP	= flag.StringSliceVarP

	PrintDefaults	= flag.PrintDefaults
)

Function symbols

• func NewApp (name string) *App
• func ParseCommands (args []string) []string
• func ParseWithFlagSet (fs *flag.FlagSet, args []string) error
• func (*App) AddCommand (name,title string, constructor func() *Command)
• func (*App) FindCommand (commands []string, fallback string) (*Command, error)
• func (*App) Help ()
• func (*App) HelpCommand (fs *flag.FlagSet, command *Command)
• func (*App) Run () error
• func (*App) RunWithArgs (args []string) error

NewApp

NewApp creates a new App instance.

func NewApp (name string) *App

ParseCommands

ParseCommands cleans up args[], returning only commands.

It looks inside args[] up until the first parameter that starts with "-", a flag parameter. We asume all the parameters before are command names.

Example: [a, b, -c, d, e] becomes [a, b].

func ParseCommands (args []string) []string

ParseWithFlagSet

ParseWithFlagSet parses flags and environment variables for a scoped FlagSet.

func ParseWithFlagSet (fs *flag.FlagSet, args []string) error

AddCommand

AddCommand adds a command to the app.

func (*App) AddCommand (name,title string, constructor func() *Command)

FindCommand

FindCommand finds a command for the app.

func (*App) FindCommand (commands []string, fallback string) (*Command, error)

Help

Help prints out registered commands for app.

func (*App) Help ()

HelpCommand

HelpCommand prints out help for a specific command.

func (*App) HelpCommand (fs *flag.FlagSet, command *Command)

Run

Run passes os.Args without the command name to RunWithArgs().

func (*App) Run () error

RunWithArgs

RunWithArgs is a cli entrypoint which sets up a cancellable context for the command.

func (*App) RunWithArgs (args []string) error