Use flag.Arg() in place of os.Args

This change allows for the introduction of additional flags, it also improves the error message shown to users when the incorrect number of arguments are passed.

Author: jonnyreeves

main.go

@@ -100,13 +100,14 @@ func main() {
 		return
 	}
 
-	if len(os.Args) < 6 {
+	if flag.NArg() != 5 {
+		log.Printf("Error: Invalid number of arguments (got %d, expected 5)\n\n", flag.NArg())
 		log.Fatal(usage)
 	}
 
-	userRepo := strings.Split(os.Args[1], "/")
+	userRepo := strings.Split(flag.Arg(0), "/")
 	if len(userRepo) != 2 {
-		log.Printf("Error: Invalid format used for username and repository: %s\n\n", os.Args[1])
+		log.Printf("Error: Invalid format used for username and repository: %s\n\n", flag.Arg(0))
 		log.Fatal(usage)
 	}
 
@@ -121,22 +122,22 @@ Please refer to https://help.github.com/articles/creating-an-access-token-for-co
 
 	if debug {
 		log.Println("Glob pattern received: ")
-		log.Println(os.Args[5])
+		log.Println(flag.Arg(4))
 	}
 
-	filepaths, err := filepath.Glob(os.Args[5])
+	filepaths, err := filepath.Glob(flag.Arg(4))
 	if err != nil {
-		log.Fatalf("Error: Invalid glob pattern: %s\n", os.Args[5])
+		log.Fatalf("Error: Invalid glob pattern: %s\n", flag.Arg(4))
 	}
 
 	if debug {
 		log.Println("Expanded glob pattern: ")
 		log.Printf("%v\n", filepaths)
 	}
 
-	tag := os.Args[2]
-	branch := os.Args[3]
-	desc := os.Args[4]
+	tag := flag.Arg(1)
+	branch := flag.Arg(2)
+	desc := flag.Arg(3)
 
 	CreateRelease(tag, branch, desc, filepaths)
 	log.Println("Done")