flags : Help string using reflection iteration over fields

flags/flags.go

@@ -2,6 +2,7 @@ package flags
 
 import (
 	"fmt"
+	"reflect"
 	"strings"
 )
 
@@ -34,3 +35,23 @@ func MissingValueArg(args []string, i int) bool {
 func HelpMissingVal(flag string) {
 	fmt.Printf("%s needs a value assignment\n", flag)
 }
+
+// print out help string by reflecting over fields of provided opts struct
+func Help(subcmd string, opts any) {
+	v := reflect.ValueOf(opts)
+	t := v.Type()
+
+	fmt.Printf("um %s usage:\n", subcmd)
+	for i := 0; i < v.NumField(); i++ {
+		field := t.Field(i)
+		value := v.Field(i)
+		switch value.Interface().(type) {
+		case Arg:
+			fmt.Printf("%-12v string\t: %v\n", "["+strings.ToLower(field.Name)+"]", value.FieldByName("Help"))
+		case Flag[string]:
+			fmt.Printf("%-12v | %v string\t: %v\n", value.FieldByName("Long"), value.FieldByName("Short"), value.FieldByName("Help"))
+		case Flag[bool]:
+			fmt.Printf("%-12v | %v bool\t: %v\n", value.FieldByName("Long"), value.FieldByName("Short"), value.FieldByName("Help"))
+		}
+	}
+}

next/next.go

@@ -8,14 +8,16 @@ import (
 )
 
 type options struct {
-	descriptor flags.Arg
-	tags       flags.Arg
+	Descriptor flags.Arg
+	Tags       flags.Arg
+	Help       flags.Flag[bool]
 }
 
 func InitOpts() options {
 	return options{
 		flags.Arg{"", "midfix file descriptor"},
 		flags.Arg{"", "tags to add to new file"},
+		flags.Flag[bool]{"--help", "-h", false, "show help"},
 	}
 }
 
@@ -24,12 +26,15 @@ func ParseArgs(args []string) options {
 	for i, arg := range args {
 		switch {
 		case i == 0 && !flags.HasDashPrefix(arg):
-			opts.descriptor.Val = arg
+			opts.Descriptor.Val = arg
 		case i == 1 && !flags.HasDashPrefix(arg):
-			opts.tags.Val = arg
+			opts.Tags.Val = arg
 		case i >= 2:
 			fmt.Println("um next : too many args")
 			os.Exit(1)
+		case arg == opts.Help.Long || arg == opts.Help.Short:
+			flags.Help("next", opts)
+			return opts
 		}
 	}
 	return opts

tag/tag.go

@@ -7,9 +7,10 @@ import (
 )
 
 type options struct {
-	query  flags.Arg
-	date   flags.Flag[string]
-	invert flags.Flag[bool]
+	Query  flags.Arg
+	Date   flags.Flag[string]
+	Invert flags.Flag[bool]
+	Help   flags.Flag[bool]
 }
 
 func InitOpts() options {
@@ -17,6 +18,7 @@ func InitOpts() options {
 		flags.Arg{"", "tag query"},
 		flags.Flag[string]{"--date", "-d", "", "date range"},
 		flags.Flag[bool]{"--invert", "-i", false, "invert match"},
+		flags.Flag[bool]{"--help", "-h", false, "show help"},
 	}
 }
 
@@ -26,25 +28,27 @@ func ParseArgs(args []string) options {
 		return opts
 	}
 	if !flags.HasDashPrefix(args[0]) {
-		opts.query.Val = args[0]
+		opts.Query.Val = args[0]
 	}
 	for i, arg := range args {
 		switch arg {
-		case opts.invert.Long, opts.invert.Short:
-			opts.invert.Val = true
-		case opts.date.Long, opts.date.Short:
+		case opts.Invert.Long, opts.Invert.Short:
+			opts.Invert.Val = true
+		case opts.Date.Long, opts.Date.Short:
 			if flags.MissingValueArg(args, i) {
 				flags.HelpMissingVal(arg)
 				break
 			}
-			opts.date.Val = args[i+1]
+			opts.Date.Val = args[i+1]
+		case opts.Help.Long, opts.Help.Short:
+			flags.Help("tag", opts)
+			return opts
 		}
 	}
 	return opts
 }
 
 func Tag(args []string) {
-	fmt.Printf("args: %#v\n", args)
 	opts := ParseArgs(args)
 	fmt.Println(opts)
 }