Document number: N3862

Date: 2014-01-20

Towards a Transaction-safe C++ Standard Library: std::list

by Justin Gottschlich, Michael Spear, Michael Wong, et al.

This paper documents our effort to transactionalize a C++ Standard Template Library (STL) container to demonstrate the feasibility of the transactional language constructs proposed by Study Group 5 (SG5): Transactional Memory. We began this study with std::list and made it transaction-safe using the transactional memory support in GCC 4.9. The changes were minimal and were generally restricted to the addition of transaction_safe keyword to a few interfaces such as allocate, deallocate, and swap functions. The rest of the changes were added to internal helper functions. Some of the issues that we considered were the constant time complexity of std::list.size() and friends, and its const noexcept nature. This experience shows that the safety of STL containers must not be specified directly, but instead should be inherited from the type with which the container is instantiated. For our future work, we plan to expand this effort to other STL containers as well as converting the clang/llvm C++ library.

Document number: N3861

Date: 2014-01-20

SG5: Transactional Memory (TM) Meeting Minutes 2013/09/09-2014/01/20

by Michael Wong

Minutes for 2013/09/09 SG5 Conference Call ............................................................................... 2
Minutes for 2013/10/14 SG5 Conference Call ............................................................................... 6
Minutes for 2013/10/28 SG5 Conference Call ............................................................................. 11
Minutes for 2013/11/11 SG5 Conference Call ............................................................................. 15
Minutes for 2013/11/25 SG5 Conference Call ............................................................................. 19
Minutes for 2013/12/09 SG5 Conference Call ............................................................................. 22
Minutes for 2014/01/06 SG5 Conference Call ............................................................................. 27
Minutes for 2014/01/13 SG5 Conference Call ............................................................................. 31

Document number: N3859

Date: 2014-01-20

Transactional Memory Support for C++

by Victor Luchango et al.

Transactional memory supports a programming style that is intended to facilitate parallel execution with a comparatively gentle learning curve. This document describes a proposal developed by SG5 to introduce transactional constructs into C++ as a Technical Specification. It is a revision of N3718, an earlier document with the same title, presented at the September 2013 meeting in Chicago. However, this document is self-contained, and can be read independently of N3718. At the Chicago meeting, we received encouraging and helpful feedback, which we have used to revise this proposal.

Document number: N3856

Date: 2014-01-20

Unforgetting standard functions min/max as constexpr

by Gabriel Dos Reis

This short paper proposes to make the standard functions min and max constexpr. They were top on the list of motivating cases for allowing reference parameters for constexpr functions in C++11. They were forgotten after the core language change was accepted.

Document number: N3854

Date: 2014-01-17

Variable Templates For Type Traits

by Stephan T. Lavavej

This is a proposal to add variable templates like is_same_v<T, U> as less-verbose synonyms for type traits like is_same<T, U>::value.

Document number: N3853

Date: 2014-01-17

Range-Based For-Loops: The Next Generation

by Stephan T. Lavavej

This is a proposal to add the syntax "for (elem : range)". In addition to being easier for novices to learn and being clearer for everyone to read, this will encourage correctness and efficiency.

Document number: N3847

Date: 2014-01-01

Random Number Generation is Not Simple!

by Walter E. Brown

We discuss several approaches to the modern generation of random numbers using the facilities in the C++11 standard library header <random>, and solicit feedback from LEWG and LWG as to which, if any, are suitable candidates for future standardization efforts.

Document number: N3846

Date: 2014-01-01

Extending static_assert

by Walter E. Brown

This paper provides proposed wording for several variants of an oft-requested feature: a default string literal for static_assert.

Document number: N3845

Date: 2014-01-01

Greatest Common Divisor and Least Common Multiple

by Walter E. Brown

This paper proposes two frequently-used classical numeric algorithms, gcd and lcm, for header <cstdlib>. The former calculates the greatest common divisor of two integer values, while the latter calculates their least common multiple. Both functions are already typically provided in behind-the-scenes support of the standard library’s <ratio> and <chrono> headers.

Document number: N3844

Date: 2014-01-01

A SFINAE-Friendly std::iterator_traits

by Walter E. Brown

This paper proposes to reformulate the specification of iterator_traits so as to avoid a hard error when its template argument does not have the member types expected of a non-pointer iterator, and thus to make the trait conveniently usable in a SFINAE context.