(C++) std::unique_ptr

 

std::unique_ptr is an C++11 STL uncopyable smart pointer.

 

std::unique_ptr is similar to boost::scoped_ptr.

 

std::unique_ptr guarantees that its value is complete when destroyed [1].

 

 

 

 

Example

 

• std::unique_ptr example 1: basics
• std::unique_ptr example 2: custom deleter

 

 

 

 

 

Advice

 

• Use std::unique_ptr to refer to objects of polymorphic type [2]
• Prefer std::unique_ptr over std::shared_ptr [3]

 

 

 

 

 

Comparison of std::unique_ptr and boost::scoped_ptr

 

• boost::scoped_ptr can be used from every C++ standard, std::unique_ptr from C++11
• std::unique_ptr is part of the official C++11 standard
• std::unique_ptr has a 'release' member function

 

 

 

 

 

References

 

1. Working Draft, Standard for Programming Language C++. N3337. 2012-01-16. Paragraph 20.7.1.2.2: 'unique_ptr destructor [unique.ptr.single.dtor]', page 518: '1 Requires: The expression get_deleter()(get()) shall be well formed, shall have well-defined behavior, and shall not throw exceptions. [Note: The use of default_delete requires T to be a complete type. —end note]'
2. Bjarne Stroustrup. A tour of C++. 2014. ISBN: 978-0-321-958310. Chapter 11.7.5, page 131: 'Use unique_ptr to refer to objects of polymorphic type'
3. Bjarne Stroustrup. A tour of C++. 2014. ISBN: 978-0-321-958310. Chapter 11.7.8, page 131: 'Prefer unique_ptr over shared_ptr'