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CppCon 2017 Trip Report--Charles L. Wilcox

By Adrien Hamelin | Oct 3, 2017 11:22 AM | Tags: community

The title says it all.

CppCon 2017 Trip Report

by Charles L. Wilcox

From the article:

Another CppCon draws to a close, and the future looks healthy and exciting.  Also, I finally gave a Lightning Talk.

Overall, the conference experience this year was very smooth, compared to my last two times here, despite the conference growth.  There were over 1100 attendees, up from about 900 last year.  There were sometimes 7 concurrent tracks, which is larger than years past.  Again, with most every time-slot I suffer from the paradox of choice, and if I chose a less than stellar talk, I regret what I’m potentially missing elsewhere.

#CPPCON2017. Day 4. Async Rulezzz!--"No Bugs" Hare

By Adrien Hamelin | Oct 2, 2017 12:23 PM | Tags: community

It's over, but we still have reports!

#CPPCON2017. Day 4. Async Rulezzz!

by "No Bugs" Hare

From the article:

During the Day 4 of CPPCON, I had to prepare to my own talk tomorrow; still – I was able to attend all the talks I was interested in.

But before I can start – let’s discuss a thing which I just understood during CPPCON17; it is related to…

#CPPCON2017. Day 2. Why Local Allocators are a Good ...--"No Bugs" Hare

By Adrien Hamelin | Sep 27, 2017 12:46 PM | Tags: community

The conference continues!

#CPPCON2017. Day 2. Why Local Allocators are a Good Thing(tm) Performance-Wise, and Why I am Very Cautious about C++17 STL parallelized algos

by "No Bugs" Hare

From the article:

At CPPCON2017 Day 2, two talks were of special interest to me. One was a 2-hour talk about Local Allocators – and another about C++17 STL parallelised algorithms.

Bjarne Stroustrup awarded 2017 Faraday Medal

By Jordi Mon Companys | Sep 26, 2017 12:35 PM | Tags: community

The Faraday Medal is awarded for conspicuous service rendered to the advancement of science, engineering and technology:

Bjarne Stroustrup awarded 2017 Faraday Medal

by Institution of Engineering and Technology

From the article:

“I am honored and humbled to see my name among so many illustrious previous winners of the prize,” said Stroustrup. “This privilege is only possible through the superb work of the C++ community.”

Static libs do not modular make -- Thomas Young

By Thomas Young | Sep 25, 2017 04:50 AM | Tags: basics

An article about static libraries, the benefits (or non-benefits) of splitting your project into static libraries, and the knock-on effects this can have on project dependencies.

Static libs do not modular make

by Thomas Young

From the article:

A cautionary tale about statically-linked libraries, as generated by C/C++ build tools.

As a project accumulates features, and complexity, it gets harder to understand exactly what's going on, and to find your way around the source code. You need to find some way to organise the code and try and keep things manageable.

A common idea, in this situation, is to group some source files together to split out as a static library.

I'm going to argue that this actually does very little, in itself, to increase modularity, can have the effect of significantly increasing dependencies, and is maybe not such a good idea, after all.

Quick Q: What are template deduction guides in C++17?

By Adrien Hamelin | Sep 20, 2017 12:36 PM | Tags: intermediate c++17

Quick A: A solution for automatic template resolution on constructors.

Recently on SO:

What are template deduction guides in C++17?

Template deduction guides are patterns associated with a template class that tell the compiler how to translate a set of parameter (and their types) into template arguments.

The simplest example is that of std::vector and its constructor that takes an iterator pair.

template<typename Iterator>
void func(Iterator first, Iterator last)
{
  vector v(first, last);
}

The compiler needs to figure out what vector<T>'s T type will be. We know what the answer is; T should be typename std::iterator_traits<Iterator>::value_type. But how do we tell the compiler without having to type vector<typename std::iterator_traits<Iterator>::value_type>?

You use a deduction guide:

template<typename Iterator> vector(Iterator b, Iterator e) -> vector<typename std::iterator_traits<Iterator>::value_type>;

This tells the compiler that, when you call a vector constructor matching that pattern, it will deduce the vector specialization using the code on the right of ->.

You need guides when the deduction of the type from the arguments is not based on the type of one of those arguments. Initializing a vector from an initializer_list explicitly uses the vector's T, so it doesn't need a guide.

The left side doesn't necessarily specify a constructor. The way it works is that, if you use template constructor deduction on a type, it matches the arguments you pass against all deduction guides (actual constructors provide implicit guides). If there is a match, it uses that to determine which template arguments to provide to the type. But overload resolution to determine which constructor to call happens after that.

This also means that you can use guides with aggregates and aggregate initialization:

template<typename T>
struct Thingy
{
  T t;
};

Thingy(const char *) -> Thingy<std::string>;

Thingy thing{"A String"}; //thing.t is a `std::string`.

So deduction guides are only used to figure out the type being initialized. The actual process of initialization works exactly as it did before, once that determination has been made.