Discriminated Unions with boost::python and boost::variant - The Blind Guru

By Jeremy Wright | Jan 12, 2015 10:06 AM | Tags: variant python intermediate boost

A useful application of boost::variant with boost::python by Mario Lang.

boost::python and boost::variant

by Mario Lang

From the post:

However, there is one aspect of C++ data types that I couldn't figure out how to interface with Python, which are C++ discriminated unions, or more specifically, heterogeneous containers. While Python has no problems with containers containing objects of different types, C++ does not make this very easy by default.

More C++ Idioms -- WikiBooks

By Mantosh Kumar | Jan 11, 2015 08:36 AM | Tags: None

This is a catalog of reusable pieces of C++ knowledge, similar to the book on design patterns by GoF.

[An interesting experiment... Note that some material is dated, but it's a wiki. -- Ed.]

More C++ Idioms

C++ has indeed become too "expert friendly" -- Bjarne Stroustrup, The Problem with Programming, Technology Review, Nov 2006.

Stroustrup's saying is true because experts are intimately familiar with the idioms in the language. With the increase in the idioms a programmer understands, the language becomes friendlier to him or her. The objective of this open content book is to present modern C++ idioms to programmers who have moderate level of familiarity with C++, and help elevate their knowledge so that C++ feels much friendlier to them. It is designed to be an exhaustive catalog of reusable idioms that expert C++ programmers often use while programming or designing using C++. This is an effort to capture their techniques and vocabulary into a single work. This book describes the idioms in a regular format: Name-Intent-Motivation-Solution-References, which is succinct and helps speed learning. By their nature, idioms tend to have appeared in the C++ community and in published work many times. An effort has been made to refer to the original source(s) where possible; if you find a reference incomplete or incorrect, please feel free to suggest or make improvements.

The world is invited to catalog reusable pieces of C++ knowledge (similar to the book on design patterns by GoF). The goal here is to first build an exhaustive catalog of modern C++ idioms and later evolve it into an idiom language, just like a pattern language. Finally, the contents of this book can be redistributed under the terms of the GNU Free Documentation License.

Aimed toward: Anyone with an intermediate level of knowledge in C++ and supported language paradigms

 

Await, coroutines, what could that bring for game development

By simon ferquel | Jan 8, 2015 04:29 PM | Tags: intermediate experimental

[This article is interesting not only because it's about work being proposed for consideration in the Concurrency TS, but also because it's interesting that we seem to be seeing a trend of articles being published on GitHub instead of on a blog... --Ed.]

Await, coroutines, what could that bring for game development

This article shows how we can use await in way not related to threading, tasks, or asynchronous I/O, but in the context of a game, to write game logic-related code spanning accross many frames in a sequencial way, without introducing any threads with little to no performance penalty.

Ask the STL Creator about Generic Programming

By Jon Kalb | Jan 8, 2015 04:14 PM | Tags: None

An online (Slashdot) interview of Alexander Stepanov and Daniel Rose, authors of "From Mathematics to Generic Programming" is now soliciting questions.

Add a reply to this Slashdot announcement to pose a questions. Ask as many questions as you'd like, but only one question per reply please:

Interview: Ask Alexander Stepanov and Daniel E. Rose a Question

An anonymous reader writes:

"Alexander Stepanov studied mathematics at Moscow State University and has been programming since 1972. His work on foundations of programming has been supported by GE, Brooklyn Polytechnic, AT&T, HP, SGI, and, since 2002, Adobe. In 1995 he received the Dr. Dobb's Journal Excellence in Programming Award for the design of the C++ Standard Template Library. Currently, he is the Senior Principal Engineer at A9.com. Daniel E. Roseis a programmer and research scientist who has held management positions at Apple, AltaVista, Xigo, Yahoo, and is the Chief Scientist for Search at A9.com. His research focuses on all aspects of search technology, ranging from low-level algorithms for index compression to human-computer interaction issues in web search. Rose led the team at Apple that created desktop search for the Macintosh. In addition to working together, the pair have recently written a book, From Mathematics to Generic Programming. Alexander and Daniel have agreed to answer any questions you may have about their book, their work, or programming in general. As usual, ask as many as you'd like, but please, one per post."

Quick Q: Why does trying to use a std::move'd object try to copy? -- StackOverflow

By Blog Staff | Jan 7, 2015 06:08 PM | Tags: None

Quick A: Think of move is (mostly) an optimization of copy, and copy as the "slow" fallback when you can't actually move.

Fresh on SO:

Why does calling std::move on a const object call the copy constructor when passed to another object?

Specifically, the code

#include <iostream>

struct Foo {
    Foo() = default;
    Foo(Foo && x) { std::cout << "Move" << std::endl; }
    Foo(Foo const & x) = delete;
};

int main() {
    Foo const x; Foo y(std::move(x));
}

fails to compile with the message:

g++ -std=c++14 test07.cpp -o test07
test07.cpp: In function 'int main()':
test07.cpp:10:36: error: use of deleted function 'Foo::Foo(const Foo&)'
     Foo const x; Foo y(std::move(x));
                                    ^
test07.cpp:6:5: note: declared here
     Foo(Foo const & x) = delete;
     ^
Makefile:2: recipe for target 'all' failed
make: *** [all] Error 1

Certainly, I expect it to fail because we can't move a const value. At the same time, I don't understand the route that the code takes before it tries to call the copy constructor. Meaning, I know that std::move converts the element to an x-value, but I don't know how things proceed after that with respect to const.

C++ Status at the end of 2014 -- Bartlomiej Filipek

By Blog Staff | Jan 5, 2015 06:54 AM | Tags: None

A turn-of-the-year retrospective:

C++ Status at the end of 2014

by Bartlomiej Filipek

From the article:

This was a good year for C++!

Short summary (language features):

• Clang supports C++14
• GCC supports C++11 and most of C++14 (Full support in upcoming GCC 5.0)
• Intel 15.0 supports C++11 (some features on Linux/OSX only)
• Visual Studio tries to catch up with C++11, but it also introduces C++14 features as well... and it become (almost) free!

Quick Q: Why do unique_ptr and shared_ptr treat deleters differently? -- StackOverflow

By Blog Staff | Jan 5, 2015 06:39 AM | Tags: None

Quick A: Because unique_ptr is designed to be zero-overhead, whereas shared_ptr already allocates space and can easily store the type-erased deleter.

Recently on SO:

Deleter type in unique_ptr vs. shared_ptr

I thought it is very curious when I discovered that the standard defines std::unique_ptr and std::shared_ptr in two totally different ways regarding a Deleter that the pointer may own. 

C++ User Group Meetings in January

By Meeting C++ | Jan 2, 2015 06:07 AM | Tags: user groups intermediate community c++ basics

A new year, and many more user groups? In January there are already 18 planned meetings:

C++ User Group Meetings in January 2015

by Jens Weller

The Meeting List:

7.1 C++ UG Saint Louis - Deep Dive - Part 1
7.1 C++ UG Santa Barbara - Boost Units
8.1 C++ UG NRW/Aachen - Open Source mit Schwerpunkt C++
8.1 C++ UG Dresden - OpenFoam
14.1 C++ UG Utah - Group Exercism.io in C++
14.1 C++ UG San Francisco/ Bay area - Presentation and Q&A
15.1 C++ UG Madrid - De 0 a 100 (Taller)
15.1 C++ UG Hamburg - Mandelbrot mit MPI
19.1 C++ UG Denver - Denver Tech Center C++ Developers
19.1 C++ UG Austin - North Austin Monthly C/C++ Pub Social
19.1 C++ UG Juce - JUCE C++ Meetup San Francisco
20.1 C++ UG Chicago - CUDA
20.1 C++ UG Juce - JUCE C++ Meetup Los Angeles
21.1 C++ UG Bristol - Save the date
21.1 C++ UG Düsseldorf - Treffen der C++ User Gruppe NRW
22.1 C++ UG Rhein-Neckar - Summary of Meeting C++ Conference and Coding Dojo
22.1 C++ UG Munich - Expression Templates Revisited
28.1 C++ UG San Francisco/ Bay area - Workshop and Discussion Group

The Rule of The Big Four (and a half) – Move Semantics and Resource Management -- Glennan Carnie

By Mantosh Kumar | Jan 1, 2015 09:20 PM | Tags: None

In this article author discusses the cost of copying and how move semantics help to manage the resources in an efficent manner.

Move Semantics and Resource Management

In the previous article we looked at the issues of resource management in C++ and introduced “The Rule of The Big Three (and a half)”. In this article we’ll extend this concept by looking at the idea of move semantics, a feature introduced in C++11. Move semantics mean we’ll have to extend our rule to “The Rule of The Big Five” or, perhaps more correctly, “The Rule of The Big Four (and a half)”

Interlude: C++’s Strides in 2014--K-ballo

By Adrien Hamelin | Jan 1, 2015 08:28 AM | Tags: intermediate c++14

K-ballo’s look at the achievements of C++ completed in 2014 and coming up in 2017, with an overview of draft C++17 features.

Interlude

by K-ballo

From the article:

One year down the road, 2014 has gone by but not without modifications to the C++ lands. C++14 was completed, and Clang has already reached full conformance! But it's not the end of the road, while the Technical Specification (TS) documents continue to move forward, work has started on what it is intended to be C++17...