errs pkg for error code based errors

errs/errors.go

+package errs
+
+import (
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/logger"
+)
+
+/*
+Errors implements an error handler providing standardised errors for a package.
+Fields:
+
+ Errors:
+  a map from error codes to description
+
+ Package:
+  name of the package/component
+
+ Level:
+  a function mapping error code to logger.LogLevel (severity)
+  if not given, errors default to logger.InfoLevel
+*/
+type Errors struct {
+	Errors  map[int]string
+	Package string
+	Level   func(code int) logger.LogLevel
+}
+
+/*
+Error implements the standard go error interface.
+
+  errors.New(code, format, params ...interface{})
+
+Prints as:
+
+ [package] description: details
+
+where details is fmt.Sprintf(self.format, self.params...)
+*/
+type Error struct {
+	Code    int
+	Name    string
+	Package string
+	level   logger.LogLevel
+	message string
+	format  string
+	params  []interface{}
+}
+
+func (self *Errors) New(code int, format string, params ...interface{}) *Error {
+	name, ok := self.Errors[code]
+	if !ok {
+		panic("invalid error code")
+	}
+	level := logger.InfoLevel
+	if self.Level != nil {
+		level = self.Level(code)
+	}
+	return &Error{
+		Code:    code,
+		Name:    name,
+		Package: self.Package,
+		level:   level,
+		format:  format,
+		params:  params,
+	}
+}
+
+func (self Error) Error() (message string) {
+	if len(message) == 0 {
+		self.message = fmt.Sprintf("[%s] %s", self.Package, self.Name)
+		if self.format != "" {
+			self.message += ": " + fmt.Sprintf(self.format, self.params...)
+		}
+	}
+	return self.message
+}
+
+func (self Error) Log(log *logger.Logger) {
+	log.Sendln(self.level, self)
+}
+
+/*
+err.Fatal() is true if err's severity level is 0 or 1 (logger.ErrorLevel or logger.Silence)
+*/
+func (self *Error) Fatal() (fatal bool) {
+	if self.level < logger.WarnLevel {
+		fatal = true
+	}
+	return
+}

errs/errors_test.go

+package errs
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/logger"
+)
+
+func testErrors() *Errors {
+	return &Errors{
+		Package: "TEST",
+		Errors: map[int]string{
+			0: "zero",
+			1: "one",
+		},
+		Level: func(i int) (l logger.LogLevel) {
+			if i == 0 {
+				l = logger.ErrorLevel
+			} else {
+				l = logger.WarnLevel
+			}
+			return
+		},
+	}
+}
+
+func TestErrorMessage(t *testing.T) {
+	err := testErrors().New(0, "zero detail %v", "available")
+	message := fmt.Sprintf("%v", err)
+	exp := "[TEST] zero: zero detail available"
+	if message != exp {
+		t.Errorf("error message incorrect. expected %v, got %v", exp, message)
+	}
+}
+
+func TestErrorSeverity(t *testing.T) {
+	err0 := testErrors().New(0, "zero detail")
+	if !err0.Fatal() {
+		t.Errorf("error should be fatal")
+	}
+	err1 := testErrors().New(1, "one detail")
+	if err1.Fatal() {
+		t.Errorf("error should not be fatal")
+	}
+}