cmdr: added auto-env-vars-bindings feature

cli/baseopt.go

@@ -174,6 +174,23 @@ func (c *BaseOpt) GetCommandTitles() string {
 	return backtraceCmdNamesG(c, " ", false)
 }
 
+func (c *BaseOpt) GetAutoEnvVarName(prefix string, upperCase ...bool) string {
+	t := backtraceCmdNamesG(c, "_", false)
+	// last := c.Name()
+	u := false
+	for _, b := range upperCase {
+		u = b
+	}
+	if u {
+		t = strings.ToUpper(t)
+		// last = strings.ToUpper(last)
+	}
+	if prefix != "" {
+		return prefix + "_" + t // + "_" + last
+	}
+	return t // + "_" + last
+}
+
 // GetTitleName returns name/full/short string
 func (c *BaseOpt) GetTitleName() string {
 	if c.name != "" {

cli/commandmatch.go

@@ -320,6 +320,7 @@ func (c *CmdS) matchedForTG(ctx context.Context, ff *Flag) *Flag {
 				}
 			}
 		}
+
 		// mutual exclusives
 		if len(ff.mutualExclusives) > 0 {
 			root := ff.Root()

cli/config.go

@@ -41,6 +41,8 @@ type Config struct {
 	DebugScreenWriter     HelpWriter        `json:"debug_screen_writer,omitempty"`     // redirect stdout for debugging outputs
 	Args                  []string          `json:"args,omitempty"`                    // for testing
 	Env                   map[string]string `json:"env,omitempty"`                     // inject env var & values
+	AutoEnv               bool              `json:"auto_env,omitempty"`                // enable envvars auto-binding?
+	AutoEnvPrefix         string            `json:"auto_env_prefix,omitempty"`         // envvars auto-binding prefix
 }
 
 // Opt for cmdr system

cli/worker/pre.go

@@ -167,25 +167,42 @@ func (w *workerS) commandsToStoreR(ctx context.Context, root *cli.RootCommand, c
 		}
 		return
 	}
-	if cx, ok := w.root.Cmd.(*cli.CmdS); ok {
-		conf.WithinLoading(func() {
-			cx.WalkEverything(ctx, func(cc, pp cli.Cmd, ff *cli.Flag, cmdIndex, flgIndex, level int) { //nolint:revive
-				if ff != nil {
-					if evs := ff.EnvVars(); len(evs) > 0 {
-						for _, ev := range evs {
-							if v, has := os.LookupEnv(ev); has {
-								data := fromString(v, ff.DefaultValue())
-								ff.SetDefaultValue(data)
-							}
+	if w.Config.AutoEnvPrefix == "" {
+		w.Config.AutoEnvPrefix = "APP"
+	}
+	worker := func(cx cli.Cmd) {
+		// lookup all flags...
+		//    and bind the value with its envvars field;
+		//    also bind the auto-binding env vars;
+		cx.WalkEverything(ctx, func(cc, pp cli.Cmd, ff *cli.Flag, cmdIndex, flgIndex, level int) { //nolint:revive
+			if ff != nil {
+				if evs := ff.EnvVars(); len(evs) > 0 {
+					for _, ev := range evs {
+						if v, has := os.LookupEnv(ev); has {
+							data := fromString(v, ff.DefaultValue())
+							ff.SetDefaultValue(data)
 						}
 					}
-					if conf != nil {
-						conf.Set(ff.GetDottedPath(), ff.DefaultValue())
+				}
+				if w.Config.AutoEnv {
+					ev := ff.GetAutoEnvVarName(w.Config.AutoEnvPrefix, true)
+					if v, has := os.LookupEnv(ev); has {
+						data := fromString(v, ff.DefaultValue())
+						ff.SetDefaultValue(data)
 					}
 				}
-			})
+				if conf != nil {
+					conf.Set(ff.GetDottedPath(), ff.DefaultValue())
+				}
+			}
 		})
 	}
+	if cx, ok := w.root.Cmd.(*cli.CmdS); ok && cx != nil && conf != nil {
+		// using store.WithinLoading to disable onSet callbacks and reset internal modified states.
+		conf.WithinLoading(func() { worker(cx) })
+	} else if cx := w.root.Cmd; cx != nil {
+		worker(cx)
+	}
 	return
 }
 

cmdr.go

@@ -313,6 +313,41 @@ func WithDontExecuteAction(b bool) cli.Opt {
 	}
 }
 
+// WithAutoEnvBindings enables the feature which can auto-bind env-vars
+// to flags default value.
+//
+// For example, APP_JUMP_TO_FULL=1 -> Cmd{"jump.to"}.Flag{"full"}.default-value = true.
+// In this case, `APP` is default prefix so the env-var is different
+// than other normal OS env-vars (like HOME, etc.).
+//
+// You may specify another prefix optionally. For instance, prefix
+// "CT" will cause CT_JUMP_TO_FULL=1 binding to
+// Cmd{"jump.to"}.Flag{"full"}.default-value = true.
+//
+// Also you can specify the prefix with multiple section just
+// like "CT_ACCOUNT_SERVICE", it will be treated as a normal
+// plain string and concatted with the rest parts, so
+// "CT_ACCOUNT_SERVICE_JUMP_TO_FULL=1" will be bound in.
+func WithAutoEnvBindings(b bool, prefix ...string) cli.Opt {
+	return func(s *cli.Config) {
+		s.AutoEnv = b
+		for _, p := range prefix {
+			s.AutoEnvPrefix = p
+		}
+	}
+}
+
+// WithConfig allows you passing a [*cli.Config] object directly.
+func WithConfig(conf *cli.Config) cli.Opt {
+	return func(s *cli.Config) {
+		if conf == nil {
+			*s = cli.Config{}
+		} else {
+			*s = *conf
+		}
+	}
+}
+
 // func WithOnInterpretLeadingPlusSign(cb func()) cli.Opt {
 // 	return func(s *cli.Config) {
 // 		s.onInterpretLeadingPlusSign = cb

tiny/main.go

@@ -44,6 +44,8 @@ func main() {
 
 		cmdr.WithSortInHelpScreen(true),       // default it's false
 		cmdr.WithDontGroupInHelpScreen(false), // default it's false
+
+		cmdr.WithAutoEnvBindings(true),
 	)
 
 	// // simple run the parser of app and trigger the matched command's action