Why isn't there a `std::shared_ptr` in the C standard library?

A Deeper Dive into the Absence of std::shared_ptr

In the C standard library, there exists a specialized version of std::unique_ptr for arrays, std::unique_ptr, that correctly invokes delete[] in its destructor. However, such a specialization is lacking for std::shared_ptr, necessitating the use of custom deleters like the one showcased in the question.

Rationale for the Lack of Specialization

The absence of std::shared_ptr stems from a combination of factors:

• LWG Discussion: The Library Working Group (LWG) considered the idea but ultimately dismissed it due to controversy surrounding an additional feature proposed for shared_ptr.
• Lack of Formal Proposal: Despite informal discussions, no official proposal has ever been submitted to the LWG for the creation of std::shared_ptr.

Current Status and Future Prospects

Despite the historical hesitation, recent discussions have reignited interest among LWG members. While a prototype has been implemented, a formal proposal remains outstanding. The feasibility and ultimate adoption of std::shared_ptr remains uncertain.

Upcoming Developments

An open-std.org draft TS (Technical Specification) proposes array support for std::shared_ptr. This TS, if adopted, would introduce std::shared_ptr as part of the C standard.

Update for C 17

The draft TS has since been incorporated into C 17, providing official support for std::shared_ptr. Refer to case 3 of shared_ptr::shared_ptr() for details.

The above is the detailed content of Why isn't there a `std::shared_ptr` in the C standard library?. For more information, please follow other related articles on the PHP Chinese website!