Reduce memory allocation in cli.New (#96)

* Add a benchmark for cli.New

* Reduce memory allocation in cli.New

* Add TODO around the flags maps

command_test.go

@@ -610,11 +610,6 @@ func TestOptionValidation(t *testing.T) {
 			options: []cli.Option{cli.Example("comment here", "")},
 			errMsg:  "example command cannot be empty",
 		},
-		{
-			name:    "example both empty",
-			options: []cli.Option{cli.Example("", "")},
-			errMsg:  "example comment cannot be empty\nexample command cannot be empty",
-		},
 		{
 			name:    "empty short description",
 			options: []cli.Option{cli.Short("")},
@@ -832,6 +827,24 @@ func BenchmarkExecuteHelp(b *testing.B) {
 	}
 }
 
+// Benchmarks calling New to build a typical CLI.
+func BenchmarkNew(b *testing.B) {
+	for range b.N {
+		_, err := cli.New(
+			"benchy",
+			cli.Short("A typical CLI to benchmark calling cli.New"),
+			cli.Version("dev"),
+			cli.Commit("dfdddaf"),
+			cli.Example("An example", "bench --help"),
+			cli.Allow(cli.AnyArgs()),
+			cli.Run(func(cmd *cli.Command, args []string) error { return nil }),
+		)
+		if err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
 // shuffle returns a randomly ordered copy of items.
 func shuffle[T any](items []T) []T {
 	shuffled := slices.Clone(items)

internal/flag/set.go

@@ -13,6 +13,8 @@ import (
 
 // Set is a set of command line flags.
 type Set struct {
+	// TODO(@FollowTheProcess): Figure out a way so that we don't have to store 2 maps
+	// as it's very memory wasteful
 	flags      map[string]Entry // The actual stored flags, can lookup by name
 	shorthands map[rune]Entry   // The flags by shorthand
 	args       []string         // Arguments minus flags or flag values

option.go

@@ -212,15 +212,11 @@ func Long(long string) Option {
 // An arbitrary number of examples can be added to a [Command], and calls to [Example] are additive.
 func Example(comment, command string) Option {
 	f := func(cfg *config) error {
-		errs := make([]error, 0, 2) //nolint:mnd // 2 here is because we have two arguments
 		if comment == "" {
-			errs = append(errs, errors.New("example comment cannot be empty"))
+			return errors.New("example comment cannot be empty")
 		}
 		if command == "" {
-			errs = append(errs, errors.New("example command cannot be empty"))
-		}
-		if len(errs) > 0 {
-			return errors.Join(errs...)
+			return errors.New("example command cannot be empty")
 		}
 		cfg.examples = append(cfg.examples, example{comment: comment, command: command})
 		return nil