“Modern C++ Template Programming” with Nicolai Josuttis

Meeting C++ 2018 offers also a workshop with Nicolai Josuttis:

Modern C++ Template Programming

by Jens Weller

From the article:

Each and every C++ programmer uses templates. Containers such as vector<> or array<>, strings, algorithms such as sort(), iterators, and I/O streams are all implemented as generic code. Modern C++ adds type traits, smart pointers, and template member functions such as emplace(), and generic lambdas as a tricky form of generic code.

Nevertheless the knowledge and understanding of how to implement and use templates is very limited and each and every programmer is sooner or later getting uncertain.

This workshop therefore discusses templates for a whole day to make clear what it means to use templates and how to use them in practice. As a result the general understanding of templates will be improved and generic code might become more helpful and less surprising.

When to Use Enums and When to Use Tag Dispatching in C++—Jonathan Boccara

What is your preference?

When to Use Enums and When to Use Tag Dispatching in C++

by Jonathan Boccara

From the article:

Enums and tag dispatching are two ways to introduce several behaviours in the same interface in C++. With them, we can pass arguments that determine a facet of how we want a function to behave.

Even if enums and tag dispatching have that in common, they achieve it in a quite different way. Realizing what these differences are will give you tools to decide which one to use in any given situation...

Your handy cut-out-and-keep guide to std::forward and std::move—Glennan Carnie

Do you know it?

Your handy cut-out-and-keep guide to std::forward and std::move

by Glennan Carnie

From the article:

I love a good ‘quadrant’ diagram.  It brings me immense joy if I can encapsulate some wisdom, guideline or rule-of-thumb in a simple four-quadrant picture.

This time it’s the when-and-where of std::move and std::forward.  In my experience, when programmers are first introduced to move semantics, their biggest struggle is to know when (or when not) to apply std::move or std::forward.  Usually, it’s a case of “keep apply std::move until it compiles”.  I’ve been there myself.

To that end I’ve put together a couple of a simple overview quadrant graphics to help out the neophyte ‘mover-forwarder’.  The aim is to capture some simple rules-of-thumb in an easy-to-digest format...

Exceptional exploration (1)—Lucian Radu Teodorescu

Are you exceptionally curios?

Exceptional exploration (1)

by Lucian Radu Teodorescu

From the article:

To use or not to use exceptions? That is the question.

And if you have hoped for a simple answer, this is not the right blog to read. On this blog, finding the truth is always a complex endeavor, it involves a complex mix of perspectives and a variety of interpretations. If you are into truthing, read on.

In this post we would only cover the performance aspects of it. A follow up post should discuss aspects like modifiability (how easy is to write error handling) and appropriateness of using exceptions.

Quick Q: How can unique_ptr have no overhead if it needs to store the deleter?

Quick A: The default deleter does not store anything.

Recently on SO:

How can unique_ptr have no overhead if it needs to store the deleter?

std::unique_ptr<T> is quite likely to be zero-overhead (with any sane standard-library implementation). std::unique_ptr<T, D>, for an arbitrary D, is not in general zero-overhead.

The reason is simple: Empty-Base Optimisation can be used to eliminate storage of the deleter in case it's an empty (and thus stateless) type (such as std::default_delete instantiations).

Refactoring with C++17 std::optional—Bartlomiej Filipek

Isn't it better?

Refactoring with C++17 std::optional

by Bartlomiej Filipek

From the article:

There are many situations where you need to express that something is “optional” - an object that might contain a value or not. You have several options to implement such case, but with C++17 there’s probably the most helpful way: std::optional.

For today I’ve prepared one refactoring case where you can learn how to apply this new C++17 feature...

How to Reorder A Collection With the STL—Jonathan Boccara

Did you know?

How to Reorder A Collection With the STL

by Jonathan Boccara

From the article:

The STL lets you do plenty of things on collections, and one of them is to reorder the elements inside of the collection. Or, said another way, to perform a permutation on the collection.

Inded, moving elements around a collection typically takes a fair amount of complex code to write, involving for loops and iterators. And it is perhaps the area where the STL generates the most spectacular improvements, by encapsulating those complex operations behing meaningful interfaces.

Let’s see what sorts of permutations the STL offers:

  • Lexicographical permutations
  • Cyclic permutations
  • Random permutation
  • Reverse
  • Checking for permutations
  • Other permutations

optional in Containers Ⅱ — Not All std::vector Usages Are The Same—Jonathan Müller

What do you think?

optional<T> in Containers Ⅱ — Not All std::vector Usages Are The Same

by Jonathan Müller

From the article:

Okay, so in the previous post I talked about putting optional<T> in container. I came to conclusions which I though were reasonable at the time, however, people — rightfully — pointed out some flaws in my argumentation...