C++17: The two line visitor explained--Marius Elvert

By Adrien Hamelin | Apr 16, 2018 01:00 PM | Tags: c++17 advanced

The power of C++17.

C++17: The two line visitor explained

by Marius Elvert

From the article:

If you have ever used an “idiomatic” C++ variant datatype like Boost.Variant or the new C++17 std::variant, you probably wished you could assemble a visitor to dispatch on the type by assembling a couple of lambda expressions like this:

auto my_visitor = visitor{
  [&](int value) { /* ... */ },
  [&](std::string const& value) { /* ... */ },
};

Moving Ranges Around with STL Algorithms--Jonathan Boccara

By Adrien Hamelin | Apr 16, 2018 12:51 PM | Tags: intermediate

More on the STL.

Moving Ranges Around with STL Algorithms

by Jonathan Boccara

From the article:

We’ve seen various ways to achieve complex operations on ranges with STL algorithms along the posts of the STL Learning Resource.

Let’s now see how to just move collections around. A much simpler topic…

…or is it?

Quick Q: With “-fno-exceptions”, what happens with “new T”?

By Adrien Hamelin | Apr 16, 2018 12:46 PM | Tags: advanced

Quick A: The behaviour will likely stay the same.

Recently on SO:

With “-fno-exceptions”, what happens with “new T”?

The way I understand it, operator new is defined by libstdc++. If you now compile your own code with -fno-exceptions, you cannot catch any exceptions, but you will still be linking against the normal version of libstdc++, which does throw an exception.

So yes, new T will throw an exception, even with -fno-exception.

However, if you compiled libstdc++ with -fno-exception as well, things become different. Now, new T cannot throw an exception but, if I read the libstdc++ manual right it will call abort() instead.

It seems that, if you want your new T to return NULL on failure, the only way is to explicitely specify nothrow...

Boost 1.67 released

By Blog Staff | Apr 16, 2018 10:38 AM | Tags: None

Boost 1.67 is now available:

Boost Version 1.67.0

There are two new libraries:

• Contract: Contract programming for C++. All contract programming features are supported: Subcontracting, class invariants, postconditions (with old and return values), preconditions, customizable actions on assertion failure (e.g., terminate or throw), optional compilation and checking of assertions, etc, from Lorenzo Caminiti.
• HOF: Higher-order functions for C++, from Paul Fultz II.

Also, many updated libraries have been updated. See the announcement for details.

CppCast Episode 145: Blogging and Text Processing with Bartłomiej Filipek

By robwirving | Apr 13, 2018 05:15 PM | Tags: None

Episode 145 of CppCast the only podcast for C++ developers by C++ developers. In this episode Rob and Jason are joined by Bartłomiej Filipek to discuss blogging, Simplifying C++ Code with C++17, and the work he's doing at Xara.

CppCast Episode 145: Blogging and Text Processing with Bartłomiej Filipek

by Rob Irving and Jason Turner

About the interviewee:

Bartłomiej Filipek (Bartek as a shorter version) is a C++ software developer at Xara where he works mostly on text features for advanced document editors. He works remotely from Cracow/Poland. Apart from graphics applications, Bartek also has experience with game development, large-scale systems for aviation, writing graphics drivers and even biofeedback. For seven years Bartek has been regularly blogging. In the early days the topic revolved around graphics programming, and now he focuses on Core C++. In his spare time, he loves assembling trains and Lego with his little son. And he's a collector of large Lego Star Wars models.

Tailor Standard Containers to Your Needs--Arne Mertz

By Adrien Hamelin | Apr 12, 2018 10:29 AM | Tags: intermediate

It's all about expressiveness.

Tailor Standard Containers to Your Needs

by Arne Mertz

From the article:

We often use standard containers as members of our classes. In a lot of cases, the semantics we actually need is not equivalent to the semantics the containers provide...

Which One Is Better: Map of Vectors, or Multimap?--Jonathan Boccara

By Adrien Hamelin | Apr 12, 2018 10:24 AM | Tags: intermediate

Depends!

Which One Is Better: Map of Vectors, or Multimap?

by Jonathan Boccara

From the article:

While advising on how to make code more expressive on the SFME project, I came across an interesting case of choosing the right data structure, which I’ll share with you with the permission of the authors of the projects.

We had to associate a key with several values, and perform various operations. Should we use a map of vectors, or is a multimap more appropriate? Let’s see the case in more details, and compare the two solutions...

Overload 144 is now available

By Adrien Hamelin | Apr 12, 2018 10:10 AM | Tags: community

ACCU’s Overload journal of April 2018 is out. It contains the following C++ related articles.

Overload 144 is now available

From the journal:

Deeds not words
Women’s suffrage used the motto “Deeds not Words". Frances Buontempo applies this to programming. by Frances Buontempo

No News is Good News
Using ‘new’ without care can be slow. Paul Floyd uses Godbolt’s compiler explorer to see what happens when you do. by Paul Floyd

Monitoring: Turning Noise into Signal
Creating useful logging is a constant challenge. Chris Oldwood shows us how structured logging helps. by Chris Oldwood

The Interface to Component Pattern and DynaMix
Dynamic Polymorphism is hard in C++. Borislav Stanimirov demonstrates how the DynaMix library helps. by Borislav Stanimirov

5 Reasons NOT to Use std::ostream for Human-Readable Output
C++’s ostream can be hard to use. Sergey Ignatchenko suggests we use the {fmt} library instead. by Sergey Ignatchenko

Practical Cryptographical Theory for Programmers
Cryptography is a daunting subject. Deák Ferenc helps you get started. by Deák Ferenc

Ex Hackina
Machine Learning and AI are popular at the moment. Teedy Deigh takes the Turing test. by Teedy Deigh

2018-04 post-Jacksonville mailing available

By Blog Staff | Apr 11, 2018 04:50 AM | Tags: None

The full 2018-04 mailing of new standards papers is now available.

CopperSpice: Type Traits & Documentation

By Ansel Sermersheim | Apr 10, 2018 10:12 PM | Tags: tools

New videos on the CopperSpice YouTube Channel:

Type Traits

by Barbara Geller and Ansel Sermersheim

About the video:

This video covers Type Traits, what they are, and when you might want to use them. We also contrast Type Traits with Policy Classes, and show how the distinction can be very difficult to discern.

Using Doxypress

by Barbara Geller and Ansel Sermersheim

About the video:

This video is an overview of the DoxyPress C++ documentation generator. We also discuss the DoxyPressApp GUI frontend, and explain the structure and features of DoxyPress.

Please take a look and remember to subscribe!