code review 2308043: Use Errorf where appropriate.

src/pkg/rpc/jsonrpc/client.go

 // Copyright 2010 The Go 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 jsonrpc implements a JSON-RPC ClientCodec and ServerCodec
 // for the rpc package.
 package jsonrpc
 
 import (
         "fmt"
@@ skipping 69 matching lines @@
         c.mutex.Lock()
         r.ServiceMethod = c.pending[c.resp.Id]
         c.pending[c.resp.Id] = "", false
         c.mutex.Unlock()
 
         r.Error = ""
         r.Seq = c.resp.Id
         if c.resp.Error != nil {
                 x, ok := c.resp.Error.(string)
                 if !ok {
-                        return os.NewError(fmt.Sprintf("invalid error %v", c.resp.Error))
+                        return fmt.Errorf("invalid error %v", c.resp.Error)
                 }
                 if x == "" {
                         x = "unspecified error"
                 }
                 r.Error = x
         }
         return nil
 }
 
 func (c *clientCodec) ReadResponseBody(x interface{}) os.Error {
@@ skipping 11 matching lines @@
 }
 
 // Dial connects to a JSON-RPC server at the specified network address.
 func Dial(network, address string) (*rpc.Client, os.Error) {
         conn, err := net.Dial(network, "", address)
         if err != nil {
                 return nil, err
         }
         return NewClient(conn), err
 }