January 2016

P0188R0: Wording for [[fallthrough]] attribute—Andrew Tomazos

New WG21 papers are available. If you are not a committee member, please use the comments section below or the std-proposals forum for public discussion.

Document number: P0188R0

Date: 2016-01-03

Wording for [[fallthrough]] attribute

by Andrew Tomazos

Abstract:

Wording for the [[fallthrough]] attribute described in P0068R0 is proposed for application to the C++17 working draft. [[fallthrough]] captures an intent to use the feature of “falling-through” from one case block to the next, in a switch statement. It has heavy use in existing practice. Kona EWG voted SF=15, F=5, N=0, A=0, SA=0 in favor of [[fallthrough]] from P0068R0. See P0068R0 for detailed motivation/rationale.

P0187R0: Proposal of Bitfield Default Member Initializers—Andrew Tomazos

New WG21 papers are available. If you are not a committee member, please use the comments section below or the std-proposals forum for public discussion.

Document number: P0187R0

Date: 2015-11-20

P0187R0: Proposal of Bitfield Default Member Initializers

by Andrew Tomazos

Abstract:

We propose default member initializers for bitfields. Example:

struct S {
  int x : 6 = 42;
};

To ease parsing we specify a rule, roughly summarized as “you have to use =, and = always starts the initializer”.

P0212: Wording for [[maybe_unused]] attribute—Andrew Tomazos

A new WG21 paper is available. If you are not a committee member, please use the comments section below or the std-proposals forum for public discussion.

Document number: P0212R0

Date: 2016-01-31

Wording for [[maybe_unused]] attribute

by Andrew Tomazos

Excerpt:

A wording for the [[maybe_unused]] attribute is proposed for application to the C++17 Working Draft. The semantics of [[maybe_unused]] are the same as those described for [[unused]] in P0068R0 and presented to Kona EWG. Kona EWG voted SF=5, F=11, N=2, A=0, SA=0 in favor of the attribute.

See P0068R0 for detailed motivation/rationale.

P0207: Ruminations on lambda captures—Ville Voutilainen

A new WG21 paper is available. If you are not a committee member, please use the comments section below or the std-proposals forum for public discussion.

Document number: P0207R0

Date: 2016-01-28

Ruminations on lambda captures

by Ville Voutilainen

Excerpt:

The proposal for capturing *this by value (P0018) raised suggestions for a "true value capture", which led to suggestions to change capture-default that defaults to by-value capture([=]) in the case of capturing class members. This paper explores what the suggested changes to the capture-default might mean. This paper specifically doesn't try to claim that any of the changes would have an effect on any particular amount of existing code, and admits that the examples in this paper are somewhat concocted and for illustrative purposes only. 

CppCast Episode 43: Compiler Explorer with Matt Godbolt

Episode 43 of CppCast the only podcast for C++ developers by C++ developers. In this episode Rob and Jason are joined by Matt Godbolt to discuss the online Compiler Explorer project.

CppCast Episode 43: Compiler Explorer with Matt Godbolt

by Rob Irving and Jason Turner

About the interviewee:

Matt is a developer at trading firm DRW. Before that he's worked at Google, run a C++ tools company, and spent over a decade in the games industry making PC and console games. He is fascinated by performance and created GCC Explorer, to help understand how C++ code ends up looking to the processor. When not performance tuning C++ code he enjoys writing emulators for 8-bit computers in Javascript.

Using parallelism with boost::future

A new blog entry about parallelism and boost::future:

Using parallelism with boost::future

by Jens Weller

From the article:

... While I'm fine with that the application locks up kind of hard during writing a GB zip file (its only job), I'd like to be as fast as possible. Thats why I decided to parallelize the part of the application that reads the file paths via boost::filesystem...

P0206R0: Discussion about std::thread and RAII—Ville Voutilainen

A new WG21 paper is available. If you are not a committee member, please use the comments section below or the std-proposals forum for public discussion.

Document number: P0206R0

Date: 2016-01-27

Discussion about std::thread and RAII

by Ville Voutilainen

Excerpt:

C++ continues not to provide a thread type that would join() automatically on scope exit. This causes exception-safety problems, because failing to join() in all code paths causes the destructor of a std::thread to terminate(). This paper explores various ways to solve the problem.