How to implement a stateful meta-container in C++ -- Filip Roséen

By Mantosh Kumar | May 28, 2015 09:27 PM | Tags: experimental c++14 advanced

Implementing stateful meta contianer in C++ Using Modern C++.

How to implement a stateful meta-container in C++

by Filip Roséen

From the article:

This post has explained the technical aspects related to an implementation of a stateful meta-container, allowing a developer to more easily work with, and modify, a given set of entities during the phase of translation.

Together with the previous posts in this series, the formerly unstateful world of translation has gone into a stateful universe — allowing for some crazy, but conforming, implementations.

Quick Q: Why are override and final identifiers with special meaning instead of reserved keywords?

By Adrien Hamelin | May 28, 2015 02:31 PM | Tags: c++11 basics

Quick A: To avoid breaking old code, thanks to context-sensitive keywords.

Recently on SO:

Why are override and final identifiers with special meaning instead of reserved keywords?

Both the override specifier and final specifier were added in C++11. They differ from other specifiers added to C++11 such as constexpr and decltype, in that they are not keywords and so are available for use as identifiers:

int main()
{
  int override = 0 ;    // Ok
  int final = 0 ;       // Ok
  //int constexpr = 0 ; // Error
}

They are referred to as identifiers with special meaning, which is covered in the draft C++11 standard section 2.11 [lex.name] (emphasis mine):

The identifiers in Table 3 have a special meaning when appearing in a certain context. When referred to in the grammar, these identifiers are used explicitly rather than using the identifier grammar production. any ambiguity as to whether a given identifier has a special meaning is resolved to interpret the token as a regular identifier.
and Table 3 -- Identifiers with special meaning lists both override and final.

Why did these two specifiers end up being identifiers with special meaning instead of keywords?

New C++ experimental feature: The tadpole operators--Raymond Chen

By Adrien Hamelin | May 28, 2015 02:23 PM | Tags: intermediate experimental

You should read about this amazing new feature:

New C++ experimental feature: The tadpole operators

by Raymond Chen

From the article:

How often have you had to write code like this:

x = (y + 1) % 10;
x = (y + 1) * (z - 1);
x = (wcslen(s) + 1) * sizeof(wchar_t);

Since the + and - operators have such low precedence, you end up having to parenthesize them a lot, which can lead to heavily nested code that is hard to read...

Once you have been thoroughly amazed, you should also read this article:

The tadpole operators explained

Cling Aims to Provide a High-performance C++ REPL--Sergio De Simone

By Adrien Hamelin | May 28, 2015 02:14 PM | Tags: intermediate efficiency

Read about a REPL allowing to test things rapidly in C++:

Cling Aims to Provide a High-performance C++ REPL

by Sergio De Simone

From the article:

Cling is an interactive C++ interpreter that is built on top of LLVM and Clang and promises to provide a leap in productivity by going beyond the usual code-compile-run-debug C++ workflow...

Other useful materials:

• A short introduction video (youtube link)
• An article about C++ and scripting

C++17 Fold Expressions--Baptiste Wicht

By Adrien Hamelin | May 27, 2015 01:24 PM | Tags: intermediate experimental

You should read that if you want to know more about this exciting future feature of C++:

C++17 Fold Expressions

by Baptiste Wicht

From the article:

C++11 introduced variadic template to the languages. This new feature allows to write template functions and classes taking an arbitrary number of template parameters. This a feature I really like and I already used it quite a lot in my different libraries. Here is a very simple example computing the sum of the parameters:

// Good with variadics
auto old_sum(){
    return 0;
}

template<typename T1, typename... T>
auto old_sum(T1 s, T... ts){
    return s + old_sum(ts...);;
} 

// Better with fold expressions
template<typename... T>
auto fold_sum_1(T... s){
    return (... + s);
}x

Did you know? - STL algorithms and comparators

By Adrien Hamelin | May 26, 2015 08:00 AM | Tags: performance basics

Did you know?

The way the STL takes comparators is not the better thing in some cases, like with the following comparator:

[] (const T& a, const T& b) { return expensive_function(a) < expensive_function(b); }

Check it out.

Using Monads in C++ to Solve Constraints: 4. Refactoring--Bartosz Milewski

By Marco Arena | May 25, 2015 07:11 AM | Tags: intermediate

Time for refactoring functional code! Bartosz Milewski concludes his intriguing journey about the application of Monads in C++.

Using Monads in C++ to Solve Constraints: 4. Refactoring

by Bartosz Milewski

From the article:

In this installment I’d like to talk about something that a lot of functional programmers swear by: Functional programs are amazingly easy to factorize.

Acting In C++--Anthony DaSilva Jr

By Adrien Hamelin | May 25, 2015 06:35 AM | Tags: intermediate

You will find here an article about:

Acting In C++

by Anthony DaSilva Jr

From the article:

Because they’re a perfect fit for mega-core processors and they’re safer and more enjoyable to program than raw, multi-threaded, systems, I’ve been a fan of Actor-based concurrent systems ever since I experimented with Erlang and Akka (via its Java API). Thus, as a C++ programmer, I was excited to discover the “C++ Actor Framework” (CAF). Like the Akka toolkit/runtime, the CAF is based on the design of the longest living, proven, production-ready, pragmatic, actor-based, language that I know of – the venerable Erlang programming language...

C++ Best Practices: A Forkable Standards Document - Jason Turner

By Jason Turner | May 19, 2015 12:11 AM | Tags: community

A forkable coding standards and best practices document for C++.

C++ Best Practices

by Jason Turner

From the book

It (C++ Best Practices) compliments books such as Effective C++ (Meyers) and C++ Coding Standards (Alexandrescu, Sutter). We fill in some of the lower level details that they don't discuss and provide specific stylistic recommendations while also discussing how to ensure overall code quality.

...

This document is based on my personal experiences. You are not supposed to agree with it 100%. It exists as a book on github so that you can fork it for your own uses or submit back proposed changes for everyone to share.

 

Using Monads in C++ to Solve Constraints: 3. The Tale of Two Monads—Bartosz Milewski

By Marco Arena | May 18, 2015 10:33 AM | Tags: intermediate

Bartosz Milewski continues to explain how to use Monads in C++.

Using Monads in C++ to Solve Constraints: 3. The Tale of Two Monads

by Bartosz Milewski

From the article:

The functional solution to our problem involves the combination of the list monad and the state monad. Mashing two monads together is not trivial — in Haskell this is done using monad transformers — but here I’ll show you how to do it manually...