command: expose command with direct handling

This exposes flag set on commands with direct handling.

Signed-off-by: Ophestra <cat@gensokyo.uk>

command/builder.go

@@ -31,6 +31,11 @@ func newNode(output io.Writer, logf LogFunc, name, usage string) *node {
 }
 
 func (n *node) Command(name, usage string, f HandlerFunc) Node {
+	n.NewCommand(name, usage, f)
+	return n
+}
+
+func (n *node) NewCommand(name, usage string, f HandlerFunc) Flag[Node] {
 	if f == nil {
 		panic("invalid handler")
 	}
@@ -43,7 +48,7 @@ func (n *node) Command(name, usage string, f HandlerFunc) Node {
 	if !n.adopt(s) {
 		panic("attempted to initialise subcommand with non-unique name")
 	}
-	return n
+	return s
 }
 
 func (n *node) New(name, usage string) Node {

command/command.go

@@ -19,6 +19,11 @@ type (
 		Define(b *strings.Builder, set *flag.FlagSet, p any, name, usage string)
 	}
 
+	Flag[T any] interface {
+		// Flag defines a generic flag type in Node's flag set.
+		Flag(p any, name string, value FlagDefiner, usage string) T
+	}
+
 	Command interface {
 		Parse(arguments []string) error
 		baseNode[Command]
@@ -28,10 +33,12 @@ type (
 	baseNode[T any] interface {
 		// Command appends a subcommand with direct command handling.
 		Command(name, usage string, f HandlerFunc) T
-		// Flag defines a generic flag type in Node's flag set.
-		Flag(p any, name string, value FlagDefiner, usage string) T
 
 		// New returns a new subcommand tree.
 		New(name, usage string) (sub Node)
+		// NewCommand returns a new subcommand with direct command handling.
+		NewCommand(name, usage string, f HandlerFunc) (sub Flag[Node])
+
+		Flag[T]
 	}
 )