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Tricks with Default Template Arguments--Jonathan Müller

By Adrien Hamelin | Oct 28, 2020 12:01 PM | Tags: intermediate

Did you know?

Tricks with Default Template Arguments

by Jonathan Müller

From the article:

Just like regular function parameters, template parameters can also have default parameters. For class templates, this behaves mostly just like default function arguments: if you pass fewer template arguments than required, default template arguments are used to fill the remaining places. However, for function templates, it gets more complicated as template parameters for functions can be deduced by the normal function arguments. This leads to some interesting side-effects. In particular, default arguments of template parameters don’t need to be put at the end!

Let’s take a look at a couple of things we can do with default template arguments...

C++ Compile time conditional struct member variables--Saleem Ahmad

By Adrien Hamelin | Oct 12, 2020 10:35 AM | Tags: intermediate c++17

Before we get metaclasses one day?

C++ Compile time conditional struct member variables

by Saleem Ahmad

From the article:

C++ has rich set of features to do compile time calculations and optimizations to generate a better code. In one of code segment I have very large data structure in which few member variables are not used based on compile time if constexpr condition, but these variables are logged in the log line...

std::exchange Patterns: Fast, Safe, Expressive, and Probably Underused--Ben Deane

By Adrien Hamelin | Sep 28, 2020 12:21 PM | Tags: intermediate

Do you know about it?

std::exchange Patterns: Fast, Safe, Expressive, and Probably Underused

by Ben Deane

From the article:

This blog post has been a long time in the making. I gave a lightning talk on std::exchange at CppCon 2017; Jonathan first asked me to write something about std::exchange in January 2019; now here we are in the strange days of the second half of 2020. But although much has changed in the outside world, I would guess that not much has changed in most C++ codebases and in the minds of many C++ programmers with respect to using std::exchange. It could still do with more publicity and more recognition of potential use cases...

Quick Q: Is std::unique_ptr required to know the full definition of T?

By Adrien Hamelin | Sep 21, 2020 11:53 AM | Tags: intermediate

Quick A: For certain members only.

Recently on SO:

Is std::unique_ptr<T> required to know the full definition of T?

Most templates in the C++ standard library require that they be instantiated with complete types. However shared_ptr and unique_ptr are partial exceptions. Some, but not all of their members can be instantiated with incomplete types. The motivation for this is to support idioms such as pimpl using smart pointers, and without risking undefined behavior...

Refactoring from single to multi purpose

By Meeting C++ | Sep 16, 2020 05:50 AM | Tags: meetingcpp intermediate experimental community c++14 basics

Working on an old project, it came to my mind that I do this refactoring from one static path to multiple options for the 2nd time this year...

Refactoring from single to multi purpose

by Jens Weller

From the article:

For the second time this year I'm refactoring a program from a single purpose to have two or more modes of operation. Both times the start and end result is similar, just the processing is different. A classic case of using polymorphism.

The first program was a tool to process videos from speakers, find a face and export the subframe around it into a new video. The first mode was a good approach to test it, and gave results for some speakers. The second mode did a complete scan first, and then gave a smoother video for some videos. Still, both modes had to be retained...