Flag: Negatable

Negatable Flag

Normal Style

b.Flg("warning", "w").
	Description("negatable flag: <code>--no-warning</code> is available", "").
	Group("Negatable").
	Negatable(true).
	Default(false).
	Build()

A negatable flag like --warning has a companion buddy --no-warning. The two flags are just the opposite.

While end user typed --no-warning, the app.cmd.no-warning key in the Store will be set to true, on the contrary, app.cmd.warning key will be set to false.

Internally, these two flags are in a same Toggleable Group.

A negatable Flag always holds a boolean Default value, in generally,

`-W` Style

This new feature starts since cmdr v2.1.16.

parent.Flg("warnings", "W").
  Description("gcc-style negatable flag: <code>-Wunused-variable</code> and -Wno-unused-variable", "").
  Group("Negatable").
  Negatable(true, "unused-variable", "unused-parameter", "unused-function", "unused-but-set-variable", "unused-private-field", "unused-label").
  Default(false).
  Build()

A -W-style negatable flag allows you provide a set of child items.

cmdr will create a pair of toggable group flags for these child items. For example, the above sample code will make these child flags: --warnings.unused-variable/-Wunused-variable and --warnings.no-unused-variable/-Wno-unused-variable, and so on.

This -W-style negatable flag is covered from gcc -Waddress -Wno-address of GNU GCC command line options.

$ go run ./examples/negatable --warnings.unused-function
...
--warnings, -W:
    > TG: "false"
    > TG.selected: ["warnings.no-unused-function"]
        unused-variable:                false, (no-): true
        unused-parameter:               false, (no-): true
        unused-function:                true, (no-): false
        unused-but-set-variable:        false, (no-): true
        unused-private-field:           false, (no-): true
        unused-label:                   false, (no-): true
...
 
$ go run ./examples/negatable --warnings.no-unused-function
...
--warnings, -W:
    > TG: "false"
    > TG.selected: ["warnings.no-unused-function"]
        unused-variable:                false, (no-): true
        unused-parameter:               false, (no-): true
        unused-function:                false, (no-): true
        unused-but-set-variable:        false, (no-): true
        unused-private-field:           false, (no-): true
        unused-label:                   false, (no-): true
...

End-user can pass command-line arguments with -Wunused-variable to enable warnings.unused-variable option (above), or disable it with -Wno-unused-variable. Another way is using short flag -Wunused-variable and -Wno-unused-variable.

In the latest version of cmdr.v2, we also improved the help screen of a negatable flag, just like the following sample:

$ go run ./examples/negatable --help -w
00:04:15.042866Z| c/[cmdr][1] [WRN] FlagBy() return nil                  querying title="warnings" ./cli/worker/pre.go:301 worker.(*workerS).commandsToStoreR.func3.1
negatable v2.1.63 ~ Copyright © 2025 by negatable Authors ~ All Rights Reserved.
 
Usage:
 
  $ negatable  [Options...][files...]
 
Description:
 
  a sample to demo negatable flag.
 
Examples:
 
  Try to use negatable flag,
 
    $ negatable --no-warning
      cmd.Store().MustBool("no-warning") will be 'true'.
    $ negatable --warning
      cmd.Store().MustBool("warning") will be 'true'.
    $ negatable -Wunused-variable -Wno-unused-parameter
      1. cmd.Store().MustBool("warnings.unused-variable") will be 'true',
      2. cmd.Store().MustBool("warnings.no-unused-parameter") will be 'true'.
         cmd.Store().MustBool("warnings.unused-parameter") will be 'false'.
    $ negatable -Wno-unused-function -Wunused-but-set-variable
      1. cmd.Store().MustBool("warnings.unused-function") will be 'false',
         cmd.Store().MustBool("warnings.no-unused-function") will be 'true',
      2. cmd.Store().MustBool("warnings.unused-but-set-variable") will be 'true'.
    $ negatable +warning
      cmd.Store().MustBool("warning") will be 'true'.
 
Global Flags:
 
  [Negatable]
    -w,  --warning                            [x] negatable flag: --no-warning is available (Default: true)(negatable)
    -W,  --warnings                           [ ] gcc-style negatable flag: -Wunused-variable and -Wno-unused-variable (Default: false)(negatable)
         - unused-variable, no-unused-variable
         - unused-parameter, no-unused-parameter
         - unused-function, no-unused-function
         - unused-but-set-variable, no-unused-but-set-variable
         - unused-private-field, no-unused-private-field
         - unused-label, no-unused-label
  [Misc]
    -h,  --help,--info,--usage                Show this help screen (-?) [Env: HELP] (Default: true)
 
Type '-h'/'-?' or '--help' to get this help screen (254x25/46).
More: '-D'/'--debug', '-V'/'--version', '-#'/'--build-info', '--no-color'...

You've seen -W flag has the extra lines to list all of its sub-items.

Tip
When displaying a help screen (--help), specifying some flags and you've get their updated default-values to show there.
For example like above, we specified -w in the command-line, so its default-value has been updated to true in the help screen.
BTW, since a negatable flag would be implemented as a togglable flag internally, its right-part description will be leading with [x] or [ ], which the first form means a true-state choiced, and the last form means a false-state kept.

Define

To define negatable flag by .Negatable(true).Default(false) call. And by .Negatable(true, "a","b","c").Default(false) call, a -W-style flag(-set) can be defined.

main.go

package main
 
import (
	"context"
	"os"
 
	"github.com/hedzr/cmdr/v2"
	"github.com/hedzr/cmdr/v2/cli"
	"github.com/hedzr/cmdr/v2/examples/common"
	"github.com/hedzr/cmdr/v2/examples/devmode"
	// logz "github.com/hedzr/logg/slog"
)
 
const (
	appName = "negatable"
	desc    = `a sample to demo negatable flag.`
	version = cmdr.Version
	author  = ``
)
 
func main() {
	app := cmdr.Create(appName, version, author, desc).
		With(func(app cli.App) { logz.Debug("in dev mode?", "mode", devmode.InDevelopmentMode()) }).
		WithBuilders(common.AddNegatableFlag).
		WithAdders().
		// override the onAction defined in common.AddNegatableFlag()
		OnAction(func(ctx context.Context, cmd cli.Cmd, args []string) (err error) {
			// logz.PrintlnContext(ctx, cmd.Set().Dump())
 
			// v := cmd.Store().MustBool("warning")
			// w := cmd.Store().MustBool("no-warning")
			// println("warning flag: ", v)
			// println("no-warning flag: ", w)
 
			// wf := cmd.FlagBy("warning")
			// if wf != nil && wf.LeadingPlusSign() {
			// 	println("warning flag with leading plus sign: +w FOUND.")
			// }
			// return
 
			println("Dumping Store ----------\n", cmdr.Set().Dump())
 
			cmd.App().DoBuiltinAction(ctx, cli.ActionDefault)
 
			cs := cmd.Store()
 
			v := cs.MustBool("warning")
			w := cs.MustBool("no-warning")
			println("warning toggle group: ", cs.MustString("warning"))
			println("  warning flag: ", v)
			println("  no-warning flag: ", w)
 
			wf := cmd.FlagBy("warning")
			if wf != nil && wf.LeadingPlusSign() {
				println()
				println("NOTABLE: a flag with leading plus sign: +w FOUND.")
			} else {
				logz.WarnContext(ctx, "cannot found flag 'warning'")
			}
 
			sw1 := cs.MustBool("warnings.unused-variable")
			sw2 := cs.MustBool("warnings.unused-parameter")
			sw3 := cs.MustBool("warnings.unused-function")
			sw4 := cs.MustBool("warnings.unused-but-set-variable")
			sw5 := cs.MustBool("warnings.unused-private-field")
			sw6 := cs.MustBool("warnings.unused-label")
			fmt.Printf(`
 
--warnings, -W:
    > TG: %q
    > TG.selected: %q
	unused-variable:		%v, (no-): %v
	unused-parameter:		%v, (no-): %v
	unused-function:		%v, (no-): %v
	unused-but-set-variable:	%v, (no-): %v
	unused-private-field:		%v, (no-): %v
	unused-label:			%v, (no-): %v
	selected items:			%v
`,
				cs.MustString("warnings"),
				cs.MustStringSlice("warnings.selected"),
				sw1, cs.MustBool("warnings.no-unused-variable"),
				sw2, cs.MustBool("warnings.no-unused-parameter"),
				sw3, cs.MustBool("warnings.no-unused-function"),
				sw4, cs.MustBool("warnings.no-unused-but-set-variable"),
				sw5, cs.MustBool("warnings.no-unused-private-field"),
				sw6, cs.MustBool("warnings.no-unused-label"),
				cs.MustStringSlice("warnings.selected"),
			)
 
			return
		}).
		Build()
 
	ctx := context.Background()
	if err := app.Run(ctx); err != nil {
		logz.ErrorContext(ctx, "Application Error:", "err", err) // stacktrace if in debug mode/build
		os.Exit(app.SuggestRetCode())
	} else if rc := app.SuggestRetCode(); rc != 0 {
		os.Exit(rc)
	}
}

Run

The example app has these following outputs:

$ go run ./examples/negatable --no-warning
warning toggle group:  no-warning
  warning flag:  false
  no-warning flag:  true
...
$ go run ./examples/negatable --warning
warning toggle group:  true
  warning flag:  true
  no-warning flag:  false
...
$
$ go run ./examples/negatable +w -Wunused-variable -Wunused-function -h
negatable v2.1.16 ~ Copyright © 2025 by negatable Authors ~ All Rights Reserved.
 
Usage:
 
  $ negatable  [Options...][files...]
 
Description:
 
  a sample to demo negatable flag.
 
Examples:
 
  Try to use negatable flag,
 
    $ negatable --no-warning
      cmd.Store().MustBool("no-warning") will be 'true'.
    $ negatable --warning
      cmd.Store().MustBool("warning") will be 'true'.
 
Global Flags:
 
  [Negatable]
    -w, --warning                             [x] negatable flag: --no-warning is available (Default: true)
    -W, --warnings                            [ ] gcc-style negatable flag: -Wunused-variable and -Wno-unused-variable (Default: false)
  [Misc]
    -h, --help,--info,--usage                 Show this help screen (-?) [Env: HELP] (Default: false)
 
Type '-h'/'-?' or '--help' to get command help screen.
More: '-D'/'--debug', '-V'/'--version', '-#'/'--build-info', '--no-color'...
 
$
$ go run ./examples/negatable +w -Wunused-variable -Wunused-function
...
--warnings, -W:
    > TG: "false"
    > TG.selected: ["warnings.unused-variable" "warnings.unused-function"]
        unused-variable:                true, (no-): false
        unused-parameter:               false, (no-): true
        unused-function:                true, (no-): false
        unused-but-set-variable:        false, (no-): true
        unused-private-field:           false, (no-): true
        unused-label:                   false, (no-): true
$
$ go run ./examples/negatable +w -Wunused-variable -Wno-unused-function --warnings.unused-label
...
--warnings, -W:
    > TG: "false"
    > TG.selected: ["warnings.unused-variable" "warnings.no-unused-function" "warnings.unused-label"]
        unused-variable:                true, (no-): false
        unused-parameter:               false, (no-): true
        unused-function:                false, (no-): true
        unused-but-set-variable:        false, (no-): true
        unused-private-field:           false, (no-): true
        unused-label:                   true, (no-): false
$

额外的话题

Required

Toggle Group

Valid Args

Head Like

External Tool

Plus Sign

Event Handlers

Negatable Flag

Normal Style

b.Flg("warning", "w").
	Description("negatable flag: <code>--no-warning</code> is available", "").
	Group("Negatable").
	Negatable(true).
	Default(false).
	Build()

A negatable flag like --warning has a companion buddy --no-warning. The two flags are just the opposite.

While end user typed --no-warning, the app.cmd.no-warning key in the Store will be set to true, on the contrary, app.cmd.warning key will be set to false.

Internally, these two flags are in a same Toggleable Group.

A negatable Flag always holds a boolean Default value, in generally,

`-W` Style

This new feature starts since cmdr v2.1.16.

parent.Flg("warnings", "W").
  Description("gcc-style negatable flag: <code>-Wunused-variable</code> and -Wno-unused-variable", "").
  Group("Negatable").
  Negatable(true, "unused-variable", "unused-parameter", "unused-function", "unused-but-set-variable", "unused-private-field", "unused-label").
  Default(false).
  Build()

A -W-style negatable flag allows you provide a set of child items.

This -W-style negatable flag is covered from gcc -Waddress -Wno-address of GNU GCC command line options.

$ go run ./examples/negatable --warnings.unused-function
...
--warnings, -W:
    > TG: "false"
    > TG.selected: ["warnings.no-unused-function"]
        unused-variable:                false, (no-): true
        unused-parameter:               false, (no-): true
        unused-function:                true, (no-): false
        unused-but-set-variable:        false, (no-): true
        unused-private-field:           false, (no-): true
        unused-label:                   false, (no-): true
...
 
$ go run ./examples/negatable --warnings.no-unused-function
...
--warnings, -W:
    > TG: "false"
    > TG.selected: ["warnings.no-unused-function"]
        unused-variable:                false, (no-): true
        unused-parameter:               false, (no-): true
        unused-function:                false, (no-): true
        unused-but-set-variable:        false, (no-): true
        unused-private-field:           false, (no-): true
        unused-label:                   false, (no-): true
...

In the latest version of cmdr.v2, we also improved the help screen of a negatable flag, just like the following sample:

$ go run ./examples/negatable --help -w
00:04:15.042866Z| c/[cmdr][1] [WRN] FlagBy() return nil                  querying title="warnings" ./cli/worker/pre.go:301 worker.(*workerS).commandsToStoreR.func3.1
negatable v2.1.63 ~ Copyright © 2025 by negatable Authors ~ All Rights Reserved.
 
Usage:
 
  $ negatable  [Options...][files...]
 
Description:
 
  a sample to demo negatable flag.
 
Examples:
 
  Try to use negatable flag,
 
    $ negatable --no-warning
      cmd.Store().MustBool("no-warning") will be 'true'.
    $ negatable --warning
      cmd.Store().MustBool("warning") will be 'true'.
    $ negatable -Wunused-variable -Wno-unused-parameter
      1. cmd.Store().MustBool("warnings.unused-variable") will be 'true',
      2. cmd.Store().MustBool("warnings.no-unused-parameter") will be 'true'.
         cmd.Store().MustBool("warnings.unused-parameter") will be 'false'.
    $ negatable -Wno-unused-function -Wunused-but-set-variable
      1. cmd.Store().MustBool("warnings.unused-function") will be 'false',
         cmd.Store().MustBool("warnings.no-unused-function") will be 'true',
      2. cmd.Store().MustBool("warnings.unused-but-set-variable") will be 'true'.
    $ negatable +warning
      cmd.Store().MustBool("warning") will be 'true'.
 
Global Flags:
 
  [Negatable]
    -w,  --warning                            [x] negatable flag: --no-warning is available (Default: true)(negatable)
    -W,  --warnings                           [ ] gcc-style negatable flag: -Wunused-variable and -Wno-unused-variable (Default: false)(negatable)
         - unused-variable, no-unused-variable
         - unused-parameter, no-unused-parameter
         - unused-function, no-unused-function
         - unused-but-set-variable, no-unused-but-set-variable
         - unused-private-field, no-unused-private-field
         - unused-label, no-unused-label
  [Misc]
    -h,  --help,--info,--usage                Show this help screen (-?) [Env: HELP] (Default: true)
 
Type '-h'/'-?' or '--help' to get this help screen (254x25/46).
More: '-D'/'--debug', '-V'/'--version', '-#'/'--build-info', '--no-color'...

You've seen -W flag has the extra lines to list all of its sub-items.

Define

To define negatable flag by .Negatable(true).Default(false) call. And by .Negatable(true, "a","b","c").Default(false) call, a -W-style flag(-set) can be defined.

main.go

package main
 
import (
	"context"
	"os"
 
	"github.com/hedzr/cmdr/v2"
	"github.com/hedzr/cmdr/v2/cli"
	"github.com/hedzr/cmdr/v2/examples/common"
	"github.com/hedzr/cmdr/v2/examples/devmode"
	// logz "github.com/hedzr/logg/slog"
)
 
const (
	appName = "negatable"
	desc    = `a sample to demo negatable flag.`
	version = cmdr.Version
	author  = ``
)
 
func main() {
	app := cmdr.Create(appName, version, author, desc).
		With(func(app cli.App) { logz.Debug("in dev mode?", "mode", devmode.InDevelopmentMode()) }).
		WithBuilders(common.AddNegatableFlag).
		WithAdders().
		// override the onAction defined in common.AddNegatableFlag()
		OnAction(func(ctx context.Context, cmd cli.Cmd, args []string) (err error) {
			// logz.PrintlnContext(ctx, cmd.Set().Dump())
 
			// v := cmd.Store().MustBool("warning")
			// w := cmd.Store().MustBool("no-warning")
			// println("warning flag: ", v)
			// println("no-warning flag: ", w)
 
			// wf := cmd.FlagBy("warning")
			// if wf != nil && wf.LeadingPlusSign() {
			// 	println("warning flag with leading plus sign: +w FOUND.")
			// }
			// return
 
			println("Dumping Store ----------\n", cmdr.Set().Dump())
 
			cmd.App().DoBuiltinAction(ctx, cli.ActionDefault)
 
			cs := cmd.Store()
 
			v := cs.MustBool("warning")
			w := cs.MustBool("no-warning")
			println("warning toggle group: ", cs.MustString("warning"))
			println("  warning flag: ", v)
			println("  no-warning flag: ", w)
 
			wf := cmd.FlagBy("warning")
			if wf != nil && wf.LeadingPlusSign() {
				println()
				println("NOTABLE: a flag with leading plus sign: +w FOUND.")
			} else {
				logz.WarnContext(ctx, "cannot found flag 'warning'")
			}
 
			sw1 := cs.MustBool("warnings.unused-variable")
			sw2 := cs.MustBool("warnings.unused-parameter")
			sw3 := cs.MustBool("warnings.unused-function")
			sw4 := cs.MustBool("warnings.unused-but-set-variable")
			sw5 := cs.MustBool("warnings.unused-private-field")
			sw6 := cs.MustBool("warnings.unused-label")
			fmt.Printf(`
 
--warnings, -W:
    > TG: %q
    > TG.selected: %q
	unused-variable:		%v, (no-): %v
	unused-parameter:		%v, (no-): %v
	unused-function:		%v, (no-): %v
	unused-but-set-variable:	%v, (no-): %v
	unused-private-field:		%v, (no-): %v
	unused-label:			%v, (no-): %v
	selected items:			%v
`,
				cs.MustString("warnings"),
				cs.MustStringSlice("warnings.selected"),
				sw1, cs.MustBool("warnings.no-unused-variable"),
				sw2, cs.MustBool("warnings.no-unused-parameter"),
				sw3, cs.MustBool("warnings.no-unused-function"),
				sw4, cs.MustBool("warnings.no-unused-but-set-variable"),
				sw5, cs.MustBool("warnings.no-unused-private-field"),
				sw6, cs.MustBool("warnings.no-unused-label"),
				cs.MustStringSlice("warnings.selected"),
			)
 
			return
		}).
		Build()
 
	ctx := context.Background()
	if err := app.Run(ctx); err != nil {
		logz.ErrorContext(ctx, "Application Error:", "err", err) // stacktrace if in debug mode/build
		os.Exit(app.SuggestRetCode())
	} else if rc := app.SuggestRetCode(); rc != 0 {
		os.Exit(rc)
	}
}

Run

The example app has these following outputs:

$ go run ./examples/negatable --no-warning
warning toggle group:  no-warning
  warning flag:  false
  no-warning flag:  true
...
$ go run ./examples/negatable --warning
warning toggle group:  true
  warning flag:  true
  no-warning flag:  false
...
$
$ go run ./examples/negatable +w -Wunused-variable -Wunused-function -h
negatable v2.1.16 ~ Copyright © 2025 by negatable Authors ~ All Rights Reserved.
 
Usage:
 
  $ negatable  [Options...][files...]
 
Description:
 
  a sample to demo negatable flag.
 
Examples:
 
  Try to use negatable flag,
 
    $ negatable --no-warning
      cmd.Store().MustBool("no-warning") will be 'true'.
    $ negatable --warning
      cmd.Store().MustBool("warning") will be 'true'.
 
Global Flags:
 
  [Negatable]
    -w, --warning                             [x] negatable flag: --no-warning is available (Default: true)
    -W, --warnings                            [ ] gcc-style negatable flag: -Wunused-variable and -Wno-unused-variable (Default: false)
  [Misc]
    -h, --help,--info,--usage                 Show this help screen (-?) [Env: HELP] (Default: false)
 
Type '-h'/'-?' or '--help' to get command help screen.
More: '-D'/'--debug', '-V'/'--version', '-#'/'--build-info', '--no-color'...
 
$
$ go run ./examples/negatable +w -Wunused-variable -Wunused-function
...
--warnings, -W:
    > TG: "false"
    > TG.selected: ["warnings.unused-variable" "warnings.unused-function"]
        unused-variable:                true, (no-): false
        unused-parameter:               false, (no-): true
        unused-function:                true, (no-): false
        unused-but-set-variable:        false, (no-): true
        unused-private-field:           false, (no-): true
        unused-label:                   false, (no-): true
$
$ go run ./examples/negatable +w -Wunused-variable -Wno-unused-function --warnings.unused-label
...
--warnings, -W:
    > TG: "false"
    > TG.selected: ["warnings.unused-variable" "warnings.no-unused-function" "warnings.unused-label"]
        unused-variable:                true, (no-): false
        unused-parameter:               false, (no-): true
        unused-function:                false, (no-): true
        unused-but-set-variable:        false, (no-): true
        unused-private-field:           false, (no-): true
        unused-label:                   true, (no-): false
$

Flag: Negatable

Negatable Flag

Normal Style

`-W` Style

Define

Run

额外的话题

Required

Toggle Group

Valid Args

Head Like

External Tool

Plus Sign

Event Handlers

On this page

Flag: Negatable

Negatable Flag

Normal Style

`-W` Style

Define

Run

额外的话题

Required

Toggle Group

Valid Args

Head Like

External Tool

Plus Sign

Event Handlers

On this page