February 2014

Range Concepts, To Infinity And Beyond

The 4th part in Erics series on ranges:

Range Concepts, Part 4 of 4: To Infinity And Beyond

by Eric Niebler

From the Article:

Last time, I introduced a new concept, Iterable, and showed how it solved many of the problems with pair-of-iterator-style ranges. This time around, I’m going to extend Iterable in small ways to make programming with infinite ranges safer and more efficient. Disclaimer: The ideas in this post are more speculative than in the previous three. I’m looking forward to the disucussion.

C++17: I See a Monad in Your Future!

Thoughts on Monads and Futures in C++

C++17: I See a Monad in Your Future!

by Bartosz Milewski

From the Article:

If you thought you were safe from functional programming in your cozy C++ niche, think again! First the lambdas and function objects and now the monad camouflaged as std::future. But do not despair, it’s all just patterns. You won’t find them in the Gang of Four book, but once you see them, they will become obvious.

N3956: ISO/IEC CD 14882, C++ 2014, Responses to National Body Comments—Barry Hedquist

A new WG21 paper is available. A copy is linked below, and the paper will also appear in the next normal WG21 mailing. If you are not a committee member, please use the comments section below or the std-proposals forum for public discussion.

Note: This document summarizes the responses to all national comments in last year's CD ballot for C++14, which ballot resolution was completed this month at the Issaquah meeting. C++14 is now about to go out for its next ballot stage, DIS (Draft International Standard).

Document number: N3956

Date: 2014-02-24

ISO/IEC CD 14882, C++ 2014, Responses to National Body Comments

by Barry Hedquist

Excerpt:

Attached is a complete set of the WG21 Responses to National Body Comments in response to the SC22 Ballot for ISO/IEC CD 14882, Committee Draft of the revision of ISO/IEC 14882:2011, aka C++ 2014.

Range Concepts, Part 3 of 4: Introducing Iterables

The third part of Eric Nieblers Series on ranges

Range Concepts, Part 3 of 4: Introducing Iterables

by Eric Niebler

From the Article:

In the last two blog posts, I describes the challenges I’ve encountered while building a next-generation range library. In this post, I’ll sketch for you my proposed solution: refinements of the range concepts that allow delimited, infinite, and pair-o’-iterator-style ranges to fit comfortably within the concept hierarchy without loss of performance or expressive power and with increased safety. I’ve built a range library around these concepts that subsumes and extends all of the C++98 STL algorithms and the Boost.Range adaptors, so I can say with confidence that these concepts lead to a useful and consistent generic range library.

Quick Q: How can I make my constructor take a list of things, like map and vector?—StackOverflow

Quick A: By having your constructor take an initializer_list<> of the appropriate type.

Today on StackOverflow:

Constructor similar to std::map or std::vector in a class

I'm creating a class and I want to know how to create a constructor similar to the std::map or std::vector style.

std::map<std::string, std::string> map = {
    {"foo", "bar"},
    {"biz", "buz"},
    {"bez", "boz"}
};

The difference is that I don't want my class to ask for types that wants to accept, just like std::map does.

std::map<std::string, std::string>

I want my class to accept that style of arguments:

{
    {"foo", "bar"},
    {"biz", "buz"},
    {"bez", "boz"}
};

But with defined type. (std::string, Typer)

The 'Typer' is a class that I will insert as value on the std::map.

Thank you.

Clang 3.4 and C++14

With the technical completion of C++14 (we think) reported on Monday, we'd like to link to this recent post for your Friday reading pleasure to recap some of the features of C++14.

There are other articles summarizing C++14 features, but some of the short code examples in this one go beyond what we've seen posted elsewhere and are quite interesting. For example, check out primes.

Clang 3.4 and C++14

by Scott Prager

From the article:

With each new release, gcc and clang add on more C++11 and C++14 features. While clang has been behind on some features, though ahead on others, they now claim to have C++1y all worked out...

N3939: Extending make_shared to Support Arrays, Revision 2—Peter Dimov, Glen Fernandes

A new WG21 paper is available. A copy is linked below, and the paper will also appear in the next normal WG21 mailing. If you are not a committee member, please use the comments section below or the std-proposals forum for public discussion.

Document number: N3939

Date: 2014-02-17

Extending make_shared to Support Arrays, Revision 2

by Peter Dimov and Glen Fernandes

Excerpt:

This paper proposes adding array support to make_shared, via the syntax make_shared<T[]> and make_shared<T[N]>.

This revision of N3870 removes the scalar T&& overloads, reflecting the result of the LEWG review.