subcommand: add 'NewSubcommand()'

Add a 'genericSubcommand' type and "constructor" 'NewSubcommand()' to allow
for specifying subcommands that do not directly implement the 'Subcommand'
interface, but instead are specified with a static name, description, and
run function.

Signed-off-by: Victoria Dye <[email protected]>

Author: vdye

internal/argparse/subcommand.go

@@ -5,3 +5,33 @@ type Subcommand interface {
 	Description() string
 	Run(args []string) error
 }
+
+type genericSubcommand struct {
+	nameStr        string
+	descriptionStr string
+	runFunc        func([]string) error
+}
+
+func NewSubcommand(
+	name string,
+	description string,
+	runFunc func([]string) error,
+) *genericSubcommand {
+	return &genericSubcommand{
+		nameStr:        name,
+		descriptionStr: description,
+		runFunc:        runFunc,
+	}
+}
+
+func (s *genericSubcommand) Name() string {
+	return s.nameStr
+}
+
+func (s *genericSubcommand) Description() string {
+	return s.descriptionStr
+}
+
+func (s *genericSubcommand) Run(args []string) error {
+	return s.runFunc(args)
+}