C++ Readability for grt.

chrome/installer/util/copy_reg_key_work_item.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_INSTALLER_UTIL_COPY_REG_KEY_WORK_ITEM_H_
 #define CHROME_INSTALLER_UTIL_COPY_REG_KEY_WORK_ITEM_H_
 #pragma once

[Yash, 2011/10/03 02:17:37]

Why do you use both the ifdef (required by the style guide) and the #pragma once
declarations here?
Only one should be required. Please remove the #pragma.

[grt (UTC plus 2), 2011/10/03 15:35:26]

This is one of the quirks of the Chromium coding style: "When writing header
(.h) files, use both standard include guards and #pragma once."
(http://www.chromium.org/developers/coding-style#TOC-File-headers)

 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "chrome/installer/util/registry_key_backup.h"
 #include "chrome/installer/util/work_item.h"
 
 // A WorkItem subclass that replaces the contents of one registry key with that
 // of another (i.e., the destination is erased prior to the copy).  Be aware
 // that in the event of rollback the destination key's values and subkeys are
 // restored but the key and its subkeys take on their default security
 // descriptors.
 class CopyRegKeyWorkItem : public WorkItem {
  public:
   virtual ~CopyRegKeyWorkItem();
   virtual bool Do() OVERRIDE;

[Yash, 2011/10/03 02:17:37]

What's the OVERRIDE definition here for?

[grt (UTC plus 2), 2011/10/03 15:35:26]

It's a Chromium macro that expands to a compiler-specific annotation that will
trigger a compile error if this suddenly declares a new function rather than an
override of a base class's virtual function (e.g., if the base's Do() is renamed
or changed in some other way). 
(http://www.chromium.org/developers/coding-style#TOC-Code-formatting)

   virtual void Rollback() OVERRIDE;
 
  private:
   friend class WorkItem;

[Yash, 2011/10/03 02:17:37]

Please comment on why WorkItem is a friend class.

[grt (UTC plus 2), 2011/10/03 15:35:26]

Done.

 
   // Neither |source_key_path| nor |dest_key_path| may be empty.
   CopyRegKeyWorkItem(HKEY predefined_key,
                      const std::wstring& source_key_path,
                      const std::wstring& dest_key_path);
 
   // Root key in which we operate. The root key must be one of the predefined
   // keys on Windows.
   HKEY predefined_root_;
 
   // Path of the key to be copied.
   std::wstring source_key_path_;
 
   // Path of the destination key.
   std::wstring dest_key_path_;
 
   // Backup of the destination key.
   RegistryKeyBackup backup_;
 
   DISALLOW_COPY_AND_ASSIGN(CopyRegKeyWorkItem);
 };
 
 #endif  // CHROME_INSTALLER_UTIL_COPY_REG_KEY_WORK_ITEM_H_
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