Two fundamental implementations for one conceptual object -- Mark Isaacson

By Mark | Jan 31, 2015 12:09 PM | Tags: intermediate basics

From the Modern Maintainable Code blog:

Two fundamental implementations for one conceptual object

by Mark Isaacson

From the article:

This is the third article of a series on code reuse. This article discusses how to select between implementations of an object based on patterns in type information. The article uses std::unique_ptr's deleter as a practical case study.

You can find the previous article of the series here (which discusses the analogous problem as it pertains to functions), and the prelude to the next article, which looks at the same problem with one caveat: designing it so that some, but not all, of the methods will be implemented the same way no matter what types you instantiate the object with, here.

CppCon 2014 C++ on Mars: Incorporating C++ into Mars Rover Flight Software--Mark Maimone

By Adrien Hamelin | Jan 30, 2015 08:00 AM | Tags: intermediate

While we wait for CppCon 2015 in September, we’re featuring videos of some of the 100+ talks from CppCon 2014. Here is today’s feature:

C++ on Mars: Incorporating C++ into Mars Rover Flight Software

by Mark Maimone

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

One of the more challenging aspects of developing flight software (FSW) for NASA's Spirit and Opportunity Mars Exploration Rovers (MER) and Curiosity, the Mars Science Laboratory rover was how to enable them to drive themselves safely through unknown Martian terrain. When the MER mission was approved in the year 2000, JPL researchers had already demonstrated that capability on prototype rovers [1] using software written primarily in C++ on a VxWorks realtime O/S platform with shared memory. So when asked to incorporate that capability into the MER vehicles which also relied on a similar VxWorks realtime O/S, the team concluded it would be safest and most expedient to incorporate the already field-tested C++ software. But that presented a challenge, since at that point all rover FSW development was mandated to be done mainly in the C programming language.

In this talk we present some of the challenges we faced and solutions we found in deploying C++ onto the Mars Rovers. For example, dynamic allocation was initially precluded, but development of a specialized memory allocator (using the C++ "placement new" operator) enabled us to incorporate it safely into the flight system. We will discuss what aspects of C++ were incorporated, what simulation environments aided development, describe some of the tools used to validate system behavior, and explain how our success using C++ for the implementation of autonomous navigation on MER has influenced future FSW efforts.

Funny bug #20150127--Marco Foco

By Marco Arena | Jan 29, 2015 10:14 AM | Tags: intermediate boost

Marco Foco spotted a subtle bug in a piece of code that used boost::program_options. Can you find it?

Funny bug #20150127

by Marco Foco

From the article:

Two days ago I’ve been asked to have a look at a nonworking piece of code, based on boost::program_options [...] This syntax is not only unusual, but also dangerous. 

Interactive Metaprogramming Shell based on Clang

By Meeting C++ | Jan 29, 2015 03:06 AM | Tags: tmp templates intermediate experimental advanced

A new video from Meeting C++ 2014:

Interactive Metaprogramming Shell based on Clang

by Ábel Sinkovics

From the talk description:

Developing metaprograms is hard and painful. Templight (http://plc.inf.elte.hu/templight/) supports the development and debugging of template metaprograms, but the code has to be recompiled after every minor change and tricks are needed to retrieve useful information about the result...

To Be or Not to Be (an Iterator) -- Eric Niebler

By Felix Petriconi | Jan 29, 2015 01:03 AM | Tags: intermediate basics

Eric Niebler gives in his recent blog post insights about iterators

To Be or Not To Be (an Iterator)

by Eric Niebler

From the article:

Way back in 1999, when the ink on the first C++ standard was still damp, Herb Sutter posed a GoTW puzzler in the still extant C++ Report (RIP): When Is a Container Not a Container? In that article, Herb described the problems of the now-infamous vector<bool>. According to the standard’s own container requirements, vector<bool> is not a container.

In a nutshell, it’s because vector<bool>‘s iterators claim to be random-access, but they’re not. Random-access iterators, when you dereference them, must return a real reference. They can only do that if the thing they point to really exists somewhere. But the bool that a vector<bool>::iterator points to does not exist anywhere. It’s actually a bit in a packed integer, and dereferencing a vector<bool>‘s iterator returns an object of some type that merely acts like a bool& without actually being a bool&.

The lvalue/rvalue metaphor--Joseph Mansfield

By Herb Sutter | Jan 28, 2015 12:38 PM | Tags: intermediate c++11

Joseph Mansfield discusses about an important topic in C++:

The lvalue/rvalue metaphor

by Joseph Mansfield

From the article:

Every expression in C++ is either an lvalue or an rvalue. This distinction is what makes something like 5 = x; invalid, as the expression 5 is an rvalue expression and so cannot appear on the left of an assignment...

January 2015 C++ Compilers Status--Christophe Riccio

By Herb Sutter | Jan 28, 2015 12:29 PM | Tags: intermediate c++14 c++11

Christophe Riccio gives us an interesting point of view for a library author and shares the latest status of some compilers:

January 2015 C++ Compilers Status

by Christophe Riccio

From the article:

...Finally, a last issue for adopting new C++11 features is simply our own ignorance of which feature is available on all the compilers we support. To resolve that problem, I made the followiong table listing all the C++ features and their support on Clang, GCC, ICC and Visual C++...

CppCon 2014 Data-Oriented Design and C++--Mike Acton

By Adrien Hamelin | Jan 28, 2015 08:00 AM | Tags: intermediate c++11

While we wait for CppCon 2015 in September, we’re featuring videos of some of the 100+ talks from CppCon 2014. Here is today’s feature:

Data-Oriented Design and C++

by Mike Acton

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

The transformation of data is the only purpose of any program. Common approaches in C++ which are antithetical to this goal will be presented in the context of a performance-critical domain (console game development). Additionally, limitations inherent in any C++ compiler and how that affects the practical use of the language when transforming that data will be demonstrated.

Expression Templates Revisited

By Meeting C++ | Jan 28, 2015 02:45 AM | Tags: templates performance intermediate experimental efficiency advanced

A new video from Meeting C++ 2014!

Expression Templates Revisited

by Klaus Iglberger

From the talk description:

Since their invention in 1995, Expression Templates (ETs) have proven to be a valuable tool for many C++ template libraries. Especially numerics libraries quickly embraced them as salvation for the performance deficiencies of standard C++. This reputation as performance optimization...

C++ SIMD parallelism with Intel Cilk Plus and OpenMP 4.0

By Meeting C++ | Jan 27, 2015 12:59 PM | Tags: performance parallelism openmp intermediate experimental efficiency concurrency advanced

A new video from Meeting C++ 2014

C++ SIMD parallelism with Intel Cilk Plus and OpenMP 4.0

by Georg Zitzlsberger

From the talk description:

Performance is one of the most important aspects that comes to mind if deciding for a programming language. Utilizing performance of modern processors is not as straight forward as it has been decades ago. Modern processors only rarely improve serial execution of applications by increasing their frequency or adding more execution units.