C++：auto_ptr, scoped_ptr, shared_ptr and weak_ptr

簡單整理各種Smart Pointer的特色：

• auto_ptr
• Supported in C++ Standard Library
• Support Ownership Transfer
• scoped_ptr
• Supported in C++ TR1
• Not Support Ownership Transfer
• shared_ptr
• Supported in C++ TR1
• Using Reference Count
• Object copy or assignment will increase the reference count.
• weak_ptr
• Supported in C++ TR1
• Created from shared_ptr. Cannot be created alone.
• Support Ownership Transfer
• Easy and safe to check a pointer valid or not, without increasing the reference count.

延伸閱讀：

• "Using auto_ptr Effectively" by Herb Sutter
• "Smart Pointers - What, Why, Which?" by Yonat Sharon
• "Observer/Listener structures in C++ with boost’s smart pointers"