New option type 'multi'. Its value is the number of occurences of an option

opt-multi.go

@@ -0,0 +1,64 @@
+package cli
+
+import "strconv"
+
+const (
+	multiTypeName = "num"
+)
+
+type cliOptionMulti struct {
+	cliOptionBase
+	defaultValue int
+	targetVar    *int
+}
+
+func (opt *cliOptionMulti) init() {
+	if opt.targetVar != nil {
+		*opt.targetVar = opt.defaultValue
+	}
+}
+
+func (opt *cliOptionMulti) getTargetVar() (any, string) {
+	var value int
+	if opt.targetVar != nil {
+		value = *opt.targetVar
+	}
+	return value, multiTypeName
+}
+
+func (opt *cliOptionMulti) requiresValue() bool {
+	return false
+}
+
+func (opt *cliOptionMulti) getDefaultValue() string {
+	return strconv.Itoa(opt.defaultValue)
+}
+
+func (opt *cliOptionMulti) getTemplate() string {
+	return opt.makeOptTemplate(false, multiTypeName)
+}
+
+func (opt *cliOptionMulti) parse(parser cliParser, argIndex int, valuePtr *string) (skipNextArg bool, err error) {
+	if opt.targetVar != nil {
+		*opt.targetVar++
+	}
+	return
+}
+
+func (cli *CliParser) AddMultiOpt(name, short string, targetVar *int, defaultValue int, description string, aliases ...string) OptReference {
+	if cli.optionExists(name, short, aliases) {
+		panic(errOptionAlreadyDefined(name))
+	}
+	opt := &cliOptionMulti{
+		cliOptionBase: cliOptionBase{
+			name:        name,
+			shortAlias:  short,
+			aliases:     aliases,
+			description: description,
+		},
+		targetVar:    targetVar,
+		defaultValue: defaultValue,
+	}
+	cli.options = append(cli.options, opt)
+	return opt
+}