add function for autocomplete

Makefile

@@ -1,6 +1,4 @@
-all:
-	@echo
-	@echo
+all: goimports vet
 
 clean:
 	rm -f go.*

parse.go

@@ -124,6 +124,16 @@ func Parse(dest ...interface{}) error {
 	return p.Parse(flags())
 }
 
+// pass in a "pretend" os.Args. Used for bash autocomplete
+func ParseFlags(flags []string, dest ...interface{}) (*Parser, error) {
+	p, err := NewParser(Config{}, dest...)
+	if err != nil {
+		return p, err
+	}
+	err = p.Parse(flags)
+	return p, err
+}
+
 // flags gets all command line arguments other than the first (program name)
 func flags() []string {
 	if len(os.Args) == 0 { // os.Args could be empty