Add ability to pass arguments to error strings

This commit adds the ability to pass in a variable number of arguments
to be used in formatting error messages that use the error handling
framework defined in core/errors.

Change-Id: I7747f2ee1ee5dbcaa3693b1e2e0c1205c159b02f
Signed-off-by: Will Lahti <wtlahti@us.ibm.com>

core/errors/errors.go

@@ -39,8 +39,9 @@ const (
 
 // Result codes
 const (
-	// Placeholder
+	// Placeholders
 	UnknownError ReasonCode = iota
+	ErrorWithArg ReasonCode = 1
 )
 
 // CallStackError is a general interface for
@@ -51,6 +52,8 @@ type CallStackError interface {
 	GetErrorCode() string
 	GetComponentCode() ComponentCode
 	GetReasonCode() ReasonCode
+	Message() string
+	MessageIn(string) string
 }
 
 type errormap map[string]map[string]map[string]string
@@ -81,6 +84,7 @@ type hlError struct {
 	stack         callstack
 	componentcode ComponentCode
 	reasoncode    ReasonCode
+	args          []interface{}
 	stackGetter   func(callstack) string
 }
 
@@ -108,7 +112,7 @@ func setupHLError(e *hlError, debug bool) {
 
 // Error comes from the error interface
 func (h *hlError) Error() string {
-	return h.componentcode.Message(h.reasoncode)
+	return h.Message()
 }
 
 // GetStack returns the call stack as a string
@@ -131,33 +135,37 @@ func (h *hlError) GetErrorCode() string {
 	return fmt.Sprintf("%d-%d", h.componentcode, h.reasoncode)
 }
 
-// Message returns the corresponding error message for this code in default language
-func (c ComponentCode) Message(reasoncode ReasonCode) string {
-	return emap[fmt.Sprintf("%d", c)][fmt.Sprintf("%d", reasoncode)][language]
+// Message returns the corresponding error message for this error in default
+// language.
+// TODO - figure out the best way to read in system language instead of using
+// hard-coded default language
+func (h *hlError) Message() string {
+	return fmt.Sprintf(emap[fmt.Sprintf("%d", h.componentcode)][fmt.Sprintf("%d", h.reasoncode)][language], h.args...)
 }
 
-// MessageIn returns the corresponding error message for this code in 'language'
-func (c ComponentCode) MessageIn(reasoncode ReasonCode, language string) string {
-	return emap[fmt.Sprintf("%d", c)][fmt.Sprintf("%d", reasoncode)][language]
+// MessageIn returns the corresponding error message for this error in 'language'
+func (h *hlError) MessageIn(language string) string {
+	return fmt.Sprintf(emap[fmt.Sprintf("%d", h.componentcode)][fmt.Sprintf("%d", h.reasoncode)][language], h.args...)
 }
 
 // Error creates a CallStackError using a specific Component Code and
 // Reason Code (no callstack is recorded)
-func Error(componentcode ComponentCode, reasoncode ReasonCode) CallStackError {
-	return newCustomError(componentcode, reasoncode, false)
+func Error(componentcode ComponentCode, reasoncode ReasonCode, args ...interface{}) CallStackError {
+	return newCustomError(componentcode, reasoncode, false, args...)
 }
 
 // ErrorWithCallstack creates a CallStackError using a specific Component Code and
 // Reason Code and fills its callstack
-func ErrorWithCallstack(componentcode ComponentCode, reasoncode ReasonCode) CallStackError {
-	return newCustomError(componentcode, reasoncode, true)
+func ErrorWithCallstack(componentcode ComponentCode, reasoncode ReasonCode, args ...interface{}) CallStackError {
+	return newCustomError(componentcode, reasoncode, true, args...)
 }
 
-func newCustomError(componentcode ComponentCode, reasoncode ReasonCode, generateStack bool) CallStackError {
+func newCustomError(componentcode ComponentCode, reasoncode ReasonCode, generateStack bool, args ...interface{}) CallStackError {
 	e := &hlError{}
 	setupHLError(e, generateStack)
 	e.componentcode = componentcode
 	e.reasoncode = reasoncode
+	e.args = args
 	return e
 }
 

core/errors/errors_json.go

@@ -19,6 +19,8 @@ package errors
 const errorCodes string = `
 {"0" :
     {"0" :
-        {"en": "An unknown error occured."}
+        {"en": "An unknown error occurred."},
+     "1":
+        {"en": "An error occurred: %s"}
     }
 }`

core/errors/errors_test.go

@@ -29,6 +29,15 @@ func TestError(t *testing.T) {
 	}
 }
 
+// TestErrorWithArg tests creating an error with a message argument
+func TestErrorWithArg(t *testing.T) {
+	e := Error(Utility, ErrorWithArg, "arg1")
+	s := e.GetStack()
+	if s != "" {
+		t.Fatalf("No error stack should have been recorded.")
+	}
+}
+
 func TestErrorWithCallstack(t *testing.T) {
 	e := ErrorWithCallstack(Utility, UnknownError)
 	s := e.GetStack()
@@ -37,6 +46,16 @@ func TestErrorWithCallstack(t *testing.T) {
 	}
 }
 
+// TestErrorWithCallstackAndArg tests creating an error with a callstack and
+// message argument
+func TestErrorWithCallstackAndArg(t *testing.T) {
+	e := ErrorWithCallstack(Utility, ErrorWithArg, "arg1")
+	s := e.GetStack()
+	if s == "" {
+		t.Fatalf("No error stack was recorded.")
+	}
+}
+
 func oops() CallStackError {
 	return Error(Utility, UnknownError)
 }
@@ -48,14 +67,36 @@ func ExampleError() {
 		fmt.Printf("%s\n", err.GetErrorCode())
 		fmt.Printf("%d\n", err.GetComponentCode())
 		fmt.Printf("%d\n", err.GetReasonCode())
-		fmt.Printf("%s\n", err.GetComponentCode().Message(err.GetReasonCode()))
-		fmt.Printf("%s", err.GetComponentCode().MessageIn(err.GetReasonCode(), "en"))
+		fmt.Printf("%s\n", err.Message())
+		fmt.Printf("%s\n", err.MessageIn("en"))
 		// Output:
-		// An unknown error occured.
+		// An unknown error occurred.
 		// 0-0
 		// 0
 		// 0
-		// An unknown error occured.
-		// An unknown error occured.
+		// An unknown error occurred.
+		// An unknown error occurred.
+	}
+}
+
+// ExampleErrorWithArg tests the output for a sample error with a message
+// argument
+func ExampleErrorWithArg() {
+	err := Error(Utility, ErrorWithArg, "arg1")
+
+	if err != nil {
+		fmt.Printf("%s\n", err.Error())
+		fmt.Printf("%s\n", err.GetErrorCode())
+		fmt.Printf("%d\n", err.GetComponentCode())
+		fmt.Printf("%d\n", err.GetReasonCode())
+		fmt.Printf("%s\n", err.Message())
+		fmt.Printf("%s\n", err.MessageIn("en"))
+		// Output:
+		// An error occurred: arg1
+		// 0-1
+		// 0
+		// 1
+		// An error occurred: arg1
+		// An error occurred: arg1
 	}
 }