Tow points of WebKit in design
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This document discusses two small designs in WebKit: the opaque pointer pattern and private data class pattern. It explains the benefits of using these patterns, such as hiding implementation details, reducing coupling, and allowing separate evolution of interfaces and implementations. It also compares opaque pointers and pimpl, noting that pimpl provides more pure encapsulation and minimizes coupling. Overall it promotes learning design patterns and idioms through small examples.
Tow points of WebKit in design
- 2. AgendaAgenda rivate Data Class Pattern AII
- 3. Private Data Class PatternPrivate Data Class Pattern 绝对的权力必然产生绝对的腐败
- 4. Country KingKing -Slaves -Properties -Lands -Slaves -Properties -Lands + 内政 + 外交 - 人事 …… + 内政 + 外交 - 人事 …… 3. 缺乏 性弹3. 缺乏 性弹 1. 高耦合1. 高耦合 2. 权力泛 来的滥带 风险2. 权力泛 来的滥带 风险
- 5. friend class ResourceHandleInternal; OwnPtr<ResourceHandleInternal> d; friend class ResourceHandleInternal; OwnPtr<ResourceHandleInternal> d; 内部数据 内部数据 对外接口及业务逻辑 对外接口及业务逻辑 Opaque PointerOpaque Pointer d-pointerd-pointer 为什么不直接使用私有成员变量？为什么不直接使用私有成员变量？
- 6. Three benefits of Opaque Pointer 1.To hide detail class implementation. 2.To add new data member without compatibility issue. 3.To includes less header files and get faster compilation time. Three benefits of Opaque Pointer 1.To hide detail class implementation. 2.To add new data member without compatibility issue. 3.To includes less header files and get faster compilation time.
- 8. The benefits of Pimpl compared to OP 1.More pure encapsulation. 2.Minimize the coupling. …… The benefits of Pimpl compared to OP 1.More pure encapsulation. 2.Minimize the coupling. ……
- 10. LibraryLibraryApplicationApplication Fragile Binary Interface Problem In C++, when anything in a class definition changes (even private members) all users of that class must be recompiled. Fragile Binary Interface Problem In C++, when anything in a class definition changes (even private members) all users of that class must be recompiled. Class BClass B Class AClass A 添加新成员 添加新成员
- 11. RResourceesource AAcquisitioncquisition IIss IInitializationnitialization 简单直接
- 12. { NestingLevelIncrementer nestingLevelIncrementer(m_scriptNestingLevel); //Do Something } { NestingLevelIncrementer nestingLevelIncrementer(m_scriptNestingLevel); //Do Something } { ++m_scriptNestingLevel; //Do Something --m_scriptNestingLevel; } { ++m_scriptNestingLevel; //Do Something --m_scriptNestingLevel; }
- 13. { ++m_scriptNestingLevel; try { //Do Something } finally { --m_scriptNestingLevel; } } { ++m_scriptNestingLevel; try { //Do Something } finally { --m_scriptNestingLevel; } } Not supported in C++ Not supported in C++
- 14. The idea is that an object's destructor is responsible for freeing resources. { NestingLevelIncrementer nestingLevelIncrementer(m_scriptNestingLevel); //Do Something } { NestingLevelIncrementer nestingLevelIncrementer(m_scriptNestingLevel); //Do Something } NestingLevelIncrementer::~NestingLevelIncrementer();NestingLevelIncrementer::~NestingLevelIncrementer();
- 15. { MutexLocker locker(m_eventsLock); //Do Something } { MutexLocker locker(m_eventsLock); //Do Something }
- 17. 好奇好奇 模式 / 规则模式 / 规则 述转述转 以小 大、不断 累……见 积以小 大、不断 累……见 积
- 18. ore C++ idioms <ore C++ idioms <LINKLINK>> sing a d-pointer <LINK>sing a d-pointer <LINK> rivate Data Class Pattern <LINK>rivate Data Class Pattern <LINK> paque Pointer <LINK>paque Pointer <LINK> impl idiom <LINK>impl idiom <LINK> ast Pimpl idiom <LINK>ast Pimpl idiom <LINK>