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CppCon 2015 Compile-time contract checking with nn--Jacob Potter

By Adrien Hamelin | Aug 31, 2016 01:56 PM | Tags: performance intermediate

Have you registered for CppCon 2016 in September? Don’t delay – Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2015 for you to enjoy. Here is today’s feature:

Compile-time contract checking with nn

by Jacob Potter

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

Tony Hoare called null pointers a “billion-dollar mistake”, but nearly every language in wide use today has them. There have been many efforts to reduce the risk of nulls creeping in where they shouldn't be, but most involve attributes or annotations rather than being part of the type system itself. Can we do better? C++'s customizable value types make it possible to solve this sort of problem.

In this talk, I’ll present a non-nullable pointer wrapper, `nn`, that’s found wide use in Dropbox’s C++ code. This helper lets us use the type system to track pointers that can't be null, and express and enforce contracts at compile time. I’ll go into some depth on the template trickery needed to make things “just work”, the toolchain bugs we found along the way, and how this tool has helped us improve our code.

CppCon 2015 Templator: Demo of a nice tool for Visualizing Template Instantiations--Peter Sommerlad

By Adrien Hamelin | Aug 29, 2016 11:22 AM | Tags: intermediate experimental community

Have you registered for CppCon 2016 in September? Don’t delay – Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2015 for you to enjoy. Here is today’s feature:

Templator: Demo of a nice tool for Visualizing Template Instantiations

by Peter Sommerlad

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

Many C++ beginners shy away from employing templates in their code, because of the myth of templates being hard. Even seasoned C++ developers can have problems manually interpreting template code correctly as Olve Maudal's C++ pub quiz demonstrates. Overloads and template specializations make it hard for programmers and also IDEs to show a developer what happens without compiling a program and even with a compile one might not get, what actually happens unless an unintelligible error message from your compiler appears.

My students tried to alleviate that problem by visualizing template instantiation and overload selection in a C++ IDE and allow to navigate through template code in instantiation context that a compiler would only create internally and that is otherwise not available for humans. While still in its nascent state I hope to show what is possible and if things go as planned at the time of the submission you should be able to solve the template pub quiz questions without running the programs.

CppCon 2015 Programming with less effort C++: Measuring the programming effort...--Sylvain Jubertie

By Adrien Hamelin | Aug 26, 2016 02:09 PM | Tags: intermediate efficiency c++14

Have you registered for CppCon 2016 in September? Don’t delay – Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2015 for you to enjoy. Here is today’s feature:

Programming with less effort C++: Measuring the programming effort with metrics

by Sylvain Jubertie

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

The C++ language and libraries propose different ways to implement codes. For example, using explicit loops or STL algorithms to traverse containers and process data. C++11&14 bring also new features to the C++ language aimed at simplifying the writing of codes. But what is the gain we can expect in term of development effort when using these different possibilities and features ? or, as a developer may ask himself: Is it viable for me to spend some time learning new C++ libraries or standards to provide less effort/spend less time on my future codes ?

Before answering these questions, we must give a definition of the development effort, and define a way to measure it. Thus, we first propose to describe existing software metrics, from the simple Single Line Of Code (SLOC) to the more complex Halstead metrics, then to implement them in an automatic tool based on Clang tools, and finally to apply them on several codes to compare their respective development efforts.

First results show that using modern C++ features like auto, decltype and lambdas help to dramatically reduce the development effort. These results may help to convince developers to use new C++ features, or to port their codes from old standards to new ones, or even switch from other languages to C++ !

CppCon 2015 `for_each_argument` explained and expanded--Vittorio Romeo

By Adrien Hamelin | Aug 24, 2016 02:13 PM | Tags: efficiency advanced

Have you registered for CppCon 2016 in September? Don’t delay – Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2015 for you to enjoy. Here is today’s feature:

`for_each_argument` explained and expanded

by Vittorio Romeo

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

During January 2015, Sean Parent posted a very interesting short piece of code on Twitter. The code iteratively iterates at compile-time over any number of function arguments, forwarding them one by one to a callable object.

How does this code work? What are the possible use cases? Can we make it even more generic and useful?

My talk answers all of the questions above, using independently compiled chronologically sequential code segments that show the audience the analysis and improvement process of `for_each_argument`.

CppCon 2015 Racing The File System--Niall Douglas

By Adrien Hamelin | Aug 22, 2016 01:44 PM | Tags: boost advanced

Have you registered for CppCon 2016 in September? Don’t delay – Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2015 for you to enjoy. Here is today’s feature:

Racing The File System

by Niall Douglas

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

Almost every programmer knows about and fears race conditions on memory where one strand of execution may concurrently update data in use by another strand of execution, leading to an inconsistent and usually dangerous inconsistent read of program state. Almost every programmer therefore is aware of mutexes, memory ordering, semaphores and the other techniques used to serialise access to memory.

Interestingly, most programmers are but vaguely aware of potential race conditions on the filing system, and as a result write code which assumes that the filing system does not suddenly change out from underneath you when you are working on it. This assumption of a static filing system introduces many potential security bugs never mind ways of crashing your program, and of course creating data loss and corruption.

This workshop will cover some of the ways in which filing system races can confound, and what portable idioms and patterns you should employ to prevent misoperation, even across networked Samba shares. Finally, an introduction of the proposed Boost library AFIO will be made which can help application developers writing filing system race free code portably.

CppChat 2015-08-21: Jason Turner and Matt Bentley

By Jon Kalb | Aug 22, 2016 04:43 AM | Tags: None

Video chat:

CppChat 08-21 with Jason and Matt

with Jason Turner, Matt Bentley, and Jon Kalb

From the chat:

We discuss CppCon sessions including Matt's session on the game-friendly containers that he has created and Jason's plenary talk about writing a game for Commodore 64 in C++17, the reprisal of his award-winning C++Now talk on "Practical Performance Practices," and his talk with Rob Irving on their CppCast experiences. Along the way we discuss the history of the 6502 and Stepanov's observation that the STL was not designed with today's hardware in mind.