Merge pull request #829 from devlights/add-flag-func-example

Author: devlights

examples/basic/flags/README.md

@@ -10,4 +10,5 @@
 | bool.go     | flags_bool     | flag.Bool(), flag.BoolVar() のサンプルです         |
 | string.go   | flags_string   | flag.String(), flag.StringVar() のサンプルです     |
 | duration.go | flags_duration | flag.Duration(), flag.DurationVar() のサンプルです |
+| func.go     | flags_func     | flag.Func() のサンプルです                         |
 |             |                |                                                    |

examples/basic/flags/examples.go

@@ -19,4 +19,5 @@ func (r *register) Regist(m mapping.ExampleMapping) {
 	m["flags_bool"] = Bool
 	m["flags_string"] = String
 	m["flags_duration"] = Duration
+	m["flags_func"] = Func
 }

examples/basic/flags/func.go

@@ -0,0 +1,52 @@
+package flags
+
+import (
+	"flag"
+	"strings"
+
+	"github.com/devlights/gomy/output"
+)
+
+// Func は、flag.Func() のサンプルです.
+//
+// flag.Func() は、func(string) error の関数を設定することで
+// 任意の処理を行うことが出来る関数です。
+//
+// # REFERENCES
+//   - https://pkg.go.dev/flag@go1.22.4#Func
+func Func() error {
+	var (
+		hs []string
+		fs = flag.NewFlagSet("", flag.ExitOnError)
+	)
+
+	fs.Func("hosts", "host names. comma separated.", func(v string) error {
+		hs = strings.Split(v, ",")
+		return nil
+	})
+
+	fs.Parse([]string{"-hosts", "example.invalid,my.local,localhost"})
+
+	for _, h := range hs {
+		output.Stdoutl("[h]", h)
+	}
+
+	return nil
+
+	/*
+		$ task
+		task: [build] go build .
+		task: [run] ./try-golang -onetime
+
+		ENTER EXAMPLE NAME: flags_func
+
+		[Name] "flags_func"
+		[h]                  example.invalid
+		[h]                  my.local
+		[h]                  localhost
+
+
+		[Elapsed] 42.06µs
+	*/
+
+}