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Overload 156 is now available

By Adrien Hamelin | Apr 14, 2020 12:21 PM | Tags: community

ACCU’s Overload journal of April 2020 is out. It contains the following C++ related articles.

Overload 156 is now available

From the journal:

R.E.S.P.E.C.T..
Respect can mean many different things. Frances Buontempo muses on its myriad meanings.

Pass the Parcel.
Python’s module and package system has many features. Steve Love explores some more advanced ones.

Quick Modular Calculations (Part 3).
This article concludes the 3-part series. Cassio Neri presents a new algorithm that also works for 64-bit operands.

Deconstructing Inheritance.
Inheritance can be overused. Lucian Radu Teodorescu considers how it can go wrong and the alternatives.

Using Compile Time Maps for Sorting.
Compile time sorting can be interesting. Norman Wilson shows how to sort a map.

Profiting from the Folly of Others.
Code referred to as a hack can raise an eyebrow. Alastair Harrison learns about accessing private members of C++ classes by investigating a header called UninitializedMemoryHacks.h

It’s About Time.
How easy is it to make code wait for a time period before doing something? Mike Crowe looks at ways to avoid problems when a system clock changes.

A Day in the Life of a Full-Stack Developer.
Many roles claim to be full stack. Teedy Deigh shares a day in the life of a full stack developer.

shared_ptr - basics and internals with examples--Hitesh Kumar

By Adrien Hamelin | Apr 14, 2020 12:19 PM | Tags: c++11 basics

Did you know it?

shared_ptr - basics and internals with examples

by Hitesh Kumar

From the article:

The C++11 std::shared_ptr<T> is a shared ownership smart pointer type. Several shared_ptr instances can share the management of an object's lifetime through a common control block. The managed object is deleted when the last owning shared_ptr is destroyed (or is made to point to another object). Memory management by shared_ptr is deterministic because the timing of a managed object's destruction is predictable and in the developer's control. Hence, std::shared_ptr brings deterministic automatic memory management to C++, without the overhead of garbage collection. Here is a basic example of shared_ptr...

Runtime Polymorphism with std::variant and std::visit--Bartlomiej Filipek

By Adrien Hamelin | Apr 13, 2020 11:00 AM | Tags: c++17

Different compromise.

Runtime Polymorphism with std::variant and std::visit

by Bartlomiej Filipek

From the article:

Runtime polymorphism usually connects with v-tables and virtual functions. However, in this blog post, I’ll show you a modern C++ technique that leverages std::variant and std::visit. This C++17 technique might not only offer better performance and value semantics, but also interesting design patterns...

Fundamental operations on type lists (Part2) -- Szilard Szaloki

By Szilard Szaloki | Apr 9, 2020 10:25 AM | Tags: None

Part2 of Fundamental operations on type lists is now available, featuring common template metaprogramming idioms, like multiple inheritance and the void* trick, demonstrated on simple metafunctions, such as push_front<>, push_back<>, pop_front<> and pop_back<>.

Fundamental operations on type lists (Part2)

by Szilard Szaloki

From the article:

Among the simplest metafunctions are push_front<> and push_back<>, since they can be easily implemented by leveraging C++11's parameter pack expansion...

Fundamental operations on type lists (Part1) -- Szilard Szaloki

By Szilard Szaloki | Apr 8, 2020 12:37 PM | Tags: None

Check out this article on basic C++ template metaprogramming concepts, such as type lists and metafunctions. This post also elaborates on alias templates and their limitations,
presents different approaches to implementing four fundamental metafunctions (first<>, front<>, last<> and back<>) and introduces a common metaprogramming primitive: apply<>.

Fundamental operations on type lists (Part1)

by Szilard Szaloki

From the article:

One of the fundamental building blocks of template metaprogramming is type lists. Dealing with them used to be a hassle, but since C++11 they are pretty much built into the language through type template parameter packs...

C++20: More Details to Coroutines--Rainer Grimm

By Adrien Hamelin | Apr 6, 2020 11:31 AM | Tags: c++20

Understand them to be able to use them.

C++20: More Details to Coroutines

by Rainer Grimm

From the article:

My job in this and further posts is to explain the framework for building coroutines. On the end, you can create your own or using an existing implementation of coroutines such as the excellent one cppcoro from Lewis Baker.

Today's post is in-between: This post is not an overview but also not in-depth dive into the coroutines framework that follows in the next posts.

The first question you may have is: When should I use coroutines?

Implementing span's comparisons--Barry Revzin

By Adrien Hamelin | Apr 6, 2020 11:20 AM | Tags: c++20 c++17

Not so easy.

Implementing span's comparisons

by Barry Revzin

From the article:

One of the new types in C++20 is std::span<T> (with its fixed- size counterpart std::span<T, N>). This is a very useful type, since it’s a type-erased view onto a contiguous range - but unlike more typical type erasure (e.g. std::function), there’s no overhead. I’ve previous written about span here.

In the initial design, std::span<T> had comparison operators that performed a deep comparison. Those operators were subsequently removed. I think that removal was a mistake, since these operators are very useful (as in, we have a span-like type in our codebase and we use these operators), but this blog isn’t going to be about why they were removed or why they should be added back.

Instead, this blog is about how to implement span’s comparison operators, since I think that is interesting and demonstrates a bunch of C++20 features all in one go. You can jump straight to the C++20 implementation here or you can just directly add it to your code base using my span_ext repo here...