simplify probe APIs

pkg/probe/wrapper.go

@@ -0,0 +1,43 @@
+/*
+ * Minimalist Object Storage, (C) 2015 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses)/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Package probe implements a simple mechanism to trace and return errors in large programs.
+package probe
+
+// wrappedError implements a container for *probe.Error.
+type wrappedError struct {
+	err *Error
+}
+
+// WrapError function wraps a *probe.Error into a 'error' compatible duck type.
+func WrapError(err *Error) error {
+	return &wrappedError{err: err}
+}
+
+// UnwrapError tries to convert generic 'error' into typed *probe.Error and returns true, false otherwise.
+func UnwrapError(err error) (*Error, bool) {
+	switch e := err.(type) {
+	case *wrappedError:
+		return e.err, true
+	default:
+		return nil, false
+	}
+}
+
+// Error interface method.
+func (w *wrappedError) Error() string {
+	return w.err.String()
+}