commands: Added a flag to enable stdin arguments

argument.go

@@ -8,11 +8,12 @@ const (
 )
 
 type Argument struct {
-	Name        string
-	Type        ArgumentType
-	Required    bool
-	Variadic    bool
-	Description string
+	Name          string
+	Type          ArgumentType
+	Required      bool
+	Variadic      bool
+	SupportsStdin bool
+	Description   string
 }
 
 func StringArg(name string, required, variadic bool, description string) Argument {
@@ -34,3 +35,8 @@ func FileArg(name string, required, variadic bool, description string) Argument
 		Description: description,
 	}
 }
+
+func (a Argument) EnableStdin() Argument {
+	a.SupportsStdin = true
+	return a
+}

cli/parse.go

@@ -171,7 +171,7 @@ func parseArgs(stringArgs []string, stdin *os.File, arguments []cmds.Argument) (
 				args = append(args, stringArgs[0])
 				stringArgs = stringArgs[1:]
 
-			} else {
+			} else if argDef.SupportsStdin {
 				// if we have a stdin, read it in and use the data as a string value
 				var buf bytes.Buffer
 				_, err := buf.ReadFrom(stdin)
@@ -192,7 +192,7 @@ func parseArgs(stringArgs []string, stdin *os.File, arguments []cmds.Argument) (
 				args = append(args, file)
 				stringArgs = stringArgs[1:]
 
-			} else {
+			} else if argDef.SupportsStdin {
 				// if we have a stdin, use that as a reader
 				args = append(args, stdin)
 				stdin = nil