By Meeting C++ | May 4, 2017 07:55 AM | Tags: user groups community
The monthly C++ User Group listing at Meeting C++:
C++ User Group Meetings in May 2017
by Jens Weller
From the article:
The monthly overview on upcoming C++ User Group Meetings. Lots of meeting are already planned for May, even more should be announced in the coming weeks.
There are 2 new C++ User Groups: Minneapolis, Stockholm (LLVM).
By Adrien Hamelin | May 2, 2017 01:47 PM | Tags: c++11 basics
Quick A: Are equivalent, but shrink_to_fit mark the intention.
Recently on SO:
shrink_to_fit() vs swap trick
The swap trick isn't actually constant-time. The cost of performing the actual swap is indeed O(1), but then there's the cost of the
std::vectordestructor firing and cleaning up all the allocated space. That can potentially have cost Ω(n) if the underlying objects have nontrivial destructors, since thestd::vectorneeds to go and invoke those destructors. There's also the cost of invoking the copy constructors for all the elements stored in the initial vector, which is similarly Ω(n).As a result, both approaches should have roughly the same complexity, except that
shrink_to_fitmore clearly telegraphs the intention and is probably more amenable to compiler optimizations.
By Marc Mutz | May 2, 2017 11:09 AM | Tags: None
The third episode of the QStringView Diaries blog series is out, in which Qt developer Marc Mutz describes the ongoing work in implementing a string-view for QString data.
QStringView Diaries: Masters Of The Overloads
by Marc Mutz
From the article:
The last blog post in this series described how to use string-views. This post is about how to design one. In particular, it’s about
QStringView‘s constructors. They evolved through a rapid succession of changes. These changes either fixed ambiguities betweenQStringandQStringViewoverloads, or improved performance. And they all have the same solution:std::enable_if, the Swiss Army Knife for overload control.This post will take you from where we naïvely started to where we made the impossible possible: overloading a function for arrays and pointers.
In case you missed them, here are the first two instalments:
QStringView Diaries: The Eagle Has Landed
QStringView Diaries: Advances in QStringLiteral
By Andrzej Krzemienski | Apr 28, 2017 06:06 AM | Tags: None
In his recent blog post Andrzej described in detail about a bug he discovered in GCC.
A bug in GCC
by Andrzej Krzemienski
From the article:
This post is to inform you about a bug in GCC that may cause memory (or other resource) leaks in your valid C++ programs.
One of the pillars of C++ philosophy is what we often call RAII: if you use classes to manage resources, use constructors for allocating resources and destructors for releasing them, the language makes sure that whatever happens, however you use such classes the resources will get properly released.
By Adrien Hamelin | Apr 24, 2017 12:43 PM | Tags: c++11 basics
Quick A: The signature of the function is first.
Recently on SO:
Syntax of final, override, const with trailing return types
The correct syntax should be:
- override and final should appear after the member function declaration, which including the trailing return type specification, i.e.
auto debug(ostream& os=cout) const ->ostream& override final;
- override and final should not be used with the member function definition outside the class definition, so just remove them:
auto Derived::debug(ostream& os) const ->ostream& { os << "dval: " << dval << endl; return os; }
By Adrien Hamelin | Apr 20, 2017 01:10 PM | Tags: community advanced
The series continues.
Making things do stuff – Part 3
by Glennan Carnie
From the article:
Previously, we’ve looked at the basics of hardware manipulation in C++ and applied that to a simple GPIO implementation.
In this article we’re going to have a look at encapsulating our code in a class and look at some of the design choices we have to make...
By Adrien Hamelin | Apr 20, 2017 01:01 PM | Tags: community
ACCU’s Overload journal of April 2017 is out. It contains the following C++ related articles.
Overload 138 is now available
From the journal:
Breadth First, Depth First, Test First
You can approach a problem top-down or bottom-up. Frances Buontempo wonders if algorithms can help us choose the most appropriate direction. by Frances Buontempo
Space invaders in Elm
Elm is a functional language which compiles to JavaScript. Ossi Hanhinen provides an overview. by Ossi Hanhinen
Single Module Builds – The Fastest Heresy in Town
Unity builds can be controversial. Andy Thomason shows how much difference they can make to build times. by Andy Thomason
An Interview: Emyr Williams
CVu has been running a series of interviews. Frances Buontempo interviews the interviewer, Emyr Williams. by Frances Buontempo(Not Really So) New Niche for C++: Browser!?
How do you run C++ in a browser? Sergey Ignatchenko demonstrates how to use Emscripten. by Sergey Ignatchenko
Contractual Loopholes
Compilers can optimise away functions you may want to time. Deák Ferenc explores ways to stop this happening. by Deák Ferenc
All About the Base
Representing numbers presents many choices. Teedy Deigh counts the ways. by Teedy Deigh
By bfilipek | Apr 19, 2017 12:09 AM | Tags: community
Is C++ job market falling or growing? Since billions of lines of code are already written it's not possible to disappear in a second. So what's the current state and the future?
C++ Jobs and Predictions
by Bartlomiej Filipek
From the article:
... if you like this area you'll be able to find a C++ job anyway. I hope C++20 will add another good reason to stick with C++ and even move from other languages... but we need to wait a few years to see it happening.
By Jonas Devlieghere | Apr 19, 2017 12:04 AM | Tags: c++11 basics
Storing unique pointers in containers is great, but how do you design an API around it?
Exposing Containers of Unique Pointers
by Jonas Devlieghere
From the article:
There's probably no reason to expose to the caller that objects are stored as unique pointers.
By Adrien Hamelin | Apr 18, 2017 01:17 PM | Tags: intermediate experimental
The future explained:
Understand ranges better with the new Cartesian Product adaptor
by Jonathan Boccara
From the article:
A couple of days ago, the range-v3 library got a new component: the view::cartesian_product adaptor.
Understanding what this component does, and the thought process that went through its creation is easy and will let you have a better grasp of the range library. (Note that you could just as well understand all the following by looking at the zip adaptor. But cartesian_product is brand new, so let’s discover this one, in order to hit two birds with one stone)...