Move multierror logic into luci-go.

common/errors/errors.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package errors
 
 import (
+        "errors"
         "fmt"
         "path/filepath"
         "runtime"
 )
 
+// New is a pass-through version of the standard errors.New function.

[M-A Ruel, 2015/07/22 18:20:36]

And what's the purpose?

[dnj, 2015/07/22 18:30:34]

Guess: one can import "...luci-go/common/errors" and still use "errors.New" in
their code.

[M-A Ruel, 2015/07/22 18:32:36]

Oh right, I forgot about the package name aliasing.

[iannucci, 2015/07/23 00:44:38]

Right... I figured this was easier than fixing the aliasing issue.

+var New = errors.New
+
 // MarkedError is the specific error type retuned by MakeMarkFn. It's designed
 // so that you can access the underlying object if needed.
 type MarkedError struct {
         // Orig contains the original data (error or otherwise) which was passed to
         // the marker function.
         Orig interface{}
 
         msgFmt string
 }
 
 func (te *MarkedError) Error() string {

[dnj, 2015/07/23 01:03:37]

Move to markederror.go

         return fmt.Sprintf(te.msgFmt, te.Orig)
 }
 
 // MakeMarkFn returns a new 'marker' function for your library. The name parameter
 // should probably match your package name, but it can by any string which
 // will help identify the error as originating from your package.
 func MakeMarkFn(name string) func(interface{}) error {
         fmtstring1 := name + " - %s:%d - %%+v"
         fmtstring2 := name + " - %+v"
         return func(errish interface{}) error {
                 if errish == nil {
                         return nil
                 }
                 _, filename, line, gotInfo := runtime.Caller(1)
                 pfx := fmtstring2
                 if gotInfo {
                         pfx = fmt.Sprintf(fmtstring1, filepath.Base(filename), line)
                 }
                 return &MarkedError{errish, pfx}
         }
 }