Quick Q: How to make my custom type to work with “range-based for loops”?

By Adrien Hamelin | Jul 10, 2017 12:14 PM | Tags: intermediate c++11

Quick A: Create member functions begin() and end() returning an iterator.

Recently on SO:

How to make my custom type to work with “range-based for loops”?

The standard has been changed since the question (and most answers) were posted in the resolution of this defect report.

The way to make a for(:) loop work on your type X is now one of two ways:

• Create member X::begin() and X::end() that return something that acts like an iterator
• Create a free function begin(X&) and end(X&) that return something that acts like an iterator, in the same namespace as your type X.

And similar for const variations. This will work both on compilers that implement the defect report changes, and compilers that do not.

Quick Q: Initializing a C++11 string with {}

By Adrien Hamelin | Jul 10, 2017 12:08 PM | Tags: c++11 basics

Quick A: It calls the initializer_list constructor that has the same effect in this case.

Recnetly on SO:

Initializing a C++11 string with {}

The {} initialization syntax is known as the uniform initialization syntax, it has a few key differences, but in your code as is they both do the same thing - construct a std::string object from the string literal "Test"

Initializing an object with an assignment is essentially the same as putting the right hand side in parentheses and constructing the object. For example the below two are the same

T obj = a;
T obj(a);

So you should be asking yourself, what is the difference between constructing a string object the following two ways

std::string{"Test"};
std::string("Test");

And the answer is that both the constructions above are the same and call the same constructor for std::string

For more on uniform initialization see https://softwareengineering.stackexchange.com/questions/133688/is-c11-uniform-initialization-a-replacement-for-the-old-style-syntax

Fuzzing beast with libFuzzer

By Meeting C++ | Jul 10, 2017 05:59 AM | Tags: security fuzzing experimental clang c++11 boost advanced

A short blog post about my experience in fuzzing beast during my boost review

Fuzzing beast with libFuzzer

by Jens Weller

From the article:

During the weekend I wanted to take a closer look at beast, a http library proposed for boost. I planned to write an http client class, as thats something I'll need in some project later anyways. I've been looking at beast on and off for a few month now, and started by reviewing the documentation and examples to get a feel for the library it self.

Making things do stuff - Part 6 and 7--Glennan Carnie

By Adrien Hamelin | Jul 7, 2017 02:03 PM | Tags: community advanced

The series continues.

Making things do stuff

by Glennan Carnie

Part 6 - Part 7

From the article:

As code designers we tend to eschew specific ‘stove-pipe’ code in favour of reusable code elements.  Up until now we’ve been coding some very specific examples so it’s probably worth looking at some more generic solutions...

Functors in C++-Part I and II--Mayank Jain

By Adrien Hamelin | Jul 7, 2017 01:59 PM | Tags: c++11 basics

And how they are used by the std:

Functors in C++

by Mayank Jain

Part I - Part II

From the article:

Functor or function object is a C++ class which defines the operator ( ). Functor let’s you create objects which “looks like” functions...

Metaclasses for embedded domain specific languages -- Simon Brand

By TartanLlama | Jul 7, 2017 12:35 PM | Tags: None

A post about an application of the new Metaclasses proposal.

Metaclasses for embedded domain specific languages

by Simon Brand

From the article:

Metaclasses are a proposed feature to C++ which will allow the creation of abstractions over classes and the extension of the language’s type definition system. Templates are a powerful host for other languages, and metaclasses only make them more so.

Modern C++ CI--Juan Medina

By Adrien Hamelin | Jul 6, 2017 11:58 AM | Tags: community

Complete set up of a project:

Modern C++ CI

by Juan Medina

From the article:

Modern C++ is great, some people are even calling it a new language, but is not only the language what is evolving the tool-chain is getter better, so doing continuous integration for cross platform projects is simple and effective.

I decide to do a simple project using some of the C++14 features and following the C++ Core Guidelines whenever its possible. The result is available in this repository.

A more realistic coroutine--Kirit Sælensminde

By Adrien Hamelin | Jul 6, 2017 11:41 AM | Tags: experimental efficiency

What’s the point of coroutines?

A more realistic coroutine

by Kirit Sælensminde

From the article:

Having gotten something working, we still have a small problem. We have a coroutine that we can start, and we can choose when to suspend it, but we can't yet resume it.

The coroutines TS describes a class std::experimental::coroutine_handle which is our interface to the coroutine itself. It's a template which is supposed to be told the promise_type we're using...

My first coroutine--Kirit Sælensminde

By Adrien Hamelin | Jul 4, 2017 01:18 PM | Tags: experimental efficiency

What's the point of coroutines?

My first coroutine

by Kirit Sælensminde

From the article:

There are more and more examples coming out of how to convert things like the use of futures into coroutines, and you may be forgiven for thinking that there is also some magic that happens in boost::future or std::future that lets this work, but that's not the case.

In C++ a coroutine is any function that contains one of the coroutine keywords in its body, that is any of co_return, co_yield or co_await.

What we're going to do is to write a very basic mechanism that allows us to use co_return to return a value from a coroutine. Coroutines are really a generalisation of a function call, and what this is going to allow us to do is to treat a coroutine as a function call. If we can't do this then we don't stand much chance of doing anything more interesting with them, but it will give us a good starter on how the machinery works...

How C++ coroutines work--Kirit Sælensminde

By Adrien Hamelin | Jul 4, 2017 01:12 PM | Tags: experimental efficiency

What's the point of coroutines?

How C++ coroutines work

by Kirit Sælensminde

From the article:

If you look at coroutines in other language, JavaScript or Python for example, you'll see that the language documents how the coroutines work. How you can use co_yield and co_await etc. (however they're spelled) and what the language does for you with them. This is all very useful, and lets you do a lot of cool things with them, but always within the confines of what the language runtime allows.

In C++ they're quite different. The compiler provides a scaffolding on which you can decide how things work. This means that C++ doesn't provide generators, but it provides you a way to write a ton of different generators that work in different ways depending on your needs.

This is what this series of articles is going to be about. Not how to use or write coroutines that work according to some pre-established pattern, but how the underlying machinery allows you to customise the way that the coroutines work...