Issue #46: now is set if the Type is ApiErrorFile or ApiErrorSyntax

_glua-tests/base.lua

@@ -1,7 +1,7 @@
 local ok, msg = pcall(function()
   dofile("notexist")
 end)
-assert(not ok and string.find(msg, "cannot open notexist"))
+assert(not ok and string.find(msg, "open.*notexist.*cannot.*"))
 
 local ok, msg = pcall(function()
   assert(getfenv(2) == _G)

auxlib.go

@@ -351,7 +351,7 @@ func (ls *LState) LoadFile(path string) (*LFunction, error) {
 		file, err = os.Open(path)
 		defer file.Close()
 		if err != nil {
-			return nil, newApiErrorS(ApiErrorFile, fmt.Sprintf("cannot open %v: %v", path, err.Error()))
+			return nil, newApiErrorE(ApiErrorFile, err)
 		}
 		reader = file
 	}

state.go

@@ -23,16 +23,22 @@ type ApiError struct {
 	Type       ApiErrorType
 	Object     LValue
 	StackTrace string
+	// Underlying error. This attribute is set only if the Type is ApiErrorFile or ApiErrorSyntax
+	Cause error
 }
 
 func newApiError(code ApiErrorType, object LValue) *ApiError {
-	return &ApiError{code, object, ""}
+	return &ApiError{code, object, "", nil}
 }
 
 func newApiErrorS(code ApiErrorType, message string) *ApiError {
 	return newApiError(code, LString(message))
 }
 
+func newApiErrorE(code ApiErrorType, err error) *ApiError {
+	return &ApiError{code, LString(err.Error()), "", err}
+}
+
 func (e *ApiError) Error() string {
 	if len(e.StackTrace) > 0 {
 		return fmt.Sprintf("%s\n%s", e.Object.String(), e.StackTrace)
@@ -1194,10 +1200,12 @@ func (ls *LState) ToThread(n int) *LState {
 
 /* error & debug operations {{{ */
 
+// This function is equivalent to luaL_error( http://www.lua.org/manual/5.1/manual.html#luaL_error ).
 func (ls *LState) RaiseError(format string, args ...interface{}) {
 	ls.raiseError(1, format, args...)
 }
 
+// This function is equivalent to lua_error( http://www.lua.org/manual/5.1/manual.html#lua_error ).
 func (ls *LState) Error(lv LValue, level int) {
 	if str, ok := lv.(LString); ok {
 		ls.raiseError(level, string(str))
@@ -1470,11 +1478,11 @@ func (ls *LState) Register(name string, fn LGFunction) {
 func (ls *LState) Load(reader io.Reader, name string) (*LFunction, error) {
 	chunk, err := parse.Parse(reader, name)
 	if err != nil {
-		return nil, newApiErrorS(ApiErrorSyntax, err.Error())
+		return nil, newApiErrorE(ApiErrorSyntax, err)
 	}
 	proto, err := Compile(chunk, name)
 	if err != nil {
-		return nil, newApiErrorS(ApiErrorSyntax, err.Error())
+		return nil, newApiErrorE(ApiErrorSyntax, err)
 	}
 	return newLFunctionL(proto, ls.currentEnv(), 0), nil
 }