Understanding Ranges Views and View Adaptors Objects in C++20/C++23 -- Bartlomiej Filipek

By Blog Staff | Aug 27, 2023 02:50 PM | Tags: None

In this article, we’d shed some light on the implementation of ranges::reverse_view and std::views::reverse. We’ll compare them to understand the differences between views and their adaptor objects.

Understanding Ranges Views and View Adaptors Objects in C++20/C++23

By Bartlomiej Filipek

From the article:

Let’s look at an example to understand how these views work. Assume we have a range r of integers from 1 to 5. When we apply std::views::reverse to r, it creates a view representing the elements of r in the reverse order.

#include <ranges> 
#include <vector> 
#include <iostream>  

int main() {
  std::vector<int> r = {1, 2, 3, 4, 5};  
  auto reversed = r | std::views::reverse;  
  for (auto i : reversed)  
     std::cout << i << " ";   

  // same as:  
  for (auto i : r | std::views::reverse)  
     std::cout << i << " "; 
}

No, C++ static analysis does not have to be painful -- Geoffray Adde

By philsquared | Aug 26, 2023 12:26 PM | Tags: None

Static analysis as part of your CI pipeline has long been possible -- but tedious, at best, to setup. Sonar are upending that with an innovative new approach.

No, C++ static analysis does not have to be painful

by Geoffray Adde

From the article:

It seems impossible to offer serious C++ static analysis with a great configuration experience. Users must suffer the pain, or not use it at all.
Well, at Sonar we believe in making the impossible, possible and so we've gone ahead and solved this once and for all!

Perfect Forwarding Forwards Objects Not Braced Things Trying To Become Objects -- Raymond Chen

By Blog Staff | Aug 25, 2023 02:43 PM | Tags: None

In C++, perfect forwarding is the act of passing a function’s parameters to another function while preserving its reference category. It is commonly used by wrapper methods that want to pass their parameters through to another function, often a constructor.

Perfect Forwarding Forwards Objects, Not Braced Things That Are Trying To Become Objects

By Raymond Chen

From the article:

In C++, perfect forwarding is the act of passing a function’s parameters to another function while preserving its reference category. It is commonly used by wrapper methods that want to pass their parameters through to another function, often a constructor.

template<typename T, typename... Args>
std::unique_ptr<T> make_unique(Args&&... args)
{
    return std::unique_ptr<T>(
        new T(std::forward<Args>(args)...));
}

The make_unique function takes its parameters, forwards them to the T constructor, and then puts the pointer to the newly-constructed T inside a unique_ptr. Those parameters are forwarded perfectly into the constructor: If the original parameters were rvalue reference, then the constructor receives rvalue reference. If the original parameters were lvalue references, then the constructor receives lvalue reference.

But the catch is that it can forward only objects. It can’t forward “braced things that are trying to become objects”.

C++ exceptions and memory allocation failure -- Wu Yongwei

By Wu Yongwei | Aug 24, 2023 10:45 AM | Tags: None

C++ exceptions are habitually disabled in many software projects. A related issue is that these projects also encourage the use of new (nothrow) for fear of exceptions. Is it good practice or bad practice? Also, how likely are we to really encounter out-of-memory errors? I will investigate on this topic and discuss strategies to deal with memory issues.

C++ Exceptions and Memory Allocation Failure

By Wu Yongwei

From the article:

In fact, every time we initialize or modify a string, vector, or map, we may be allocating memory on the heap. If we think that new will end in an exception (and therefore choose to use new (nothrow)), exceptions may also occur when using these mechanisms. In a program that has disabled exceptions, the result will inevitably be a program crash.

Ignoring abnormal scenarios like allocating more memory than the physical memory size at a time (which would likely be a logic error in the program), can a reasonable program still experience memory allocation failures?

Dynamic CUDA with NVIDIA's Runtime Compilation -- Richard Thomson

By Legalize Adulthood | Aug 23, 2023 02:42 PM | Tags: None

Utah C++ Programmers has released a new video:

Dynamic CUDA with NVIDIA's Runtime Compilation

by Richard Thomson

From the video description:

Using CUDA is great way to accelerate tasks on the GPU. Regular CUDA programming compiles your C++ code into code that can execute on the GPU. But what if your problem domain is more dynamic and requires generation of code on the fly?

On the CPU you can use techniques like LLVM to compile code Just-in-Time (JIT) into the native CPU instruction set and call this code directly from your application. What about on the GPU?

The NVRTC (Runtime Compilation) library accepts CUDA C++ source code and creates modules of GPU ready code that you can execute on the GPU.

This month, Richard Thomson will give us an introduction to using the NVRTC library for runtime compilation and nvJitLink for runtime linking of CUDA C++ source code to execute code on the GPU. We'll use a simple fractal generator as the example, with a user provided "iteration formula" to generate a fractal image in the complex plane.

https://www.youtube.com/watch?v=9OCQb5RA-s0

C++23: static operator() and static operator[] -- Sandor Dargo

By Blog Staff | Aug 23, 2023 02:03 PM | Tags: None

In this article, we are going to review two new features of C++23. Now the language allows the call operator (operator()) and the subscription operator (operator[]) to be static.

C++23: static operator() and static operator[]

By Sandor Dargo

From the article:

static operator()

As we saw earlier in our big C++ algorithms tutorial, function objects are extensively used in the standard library to customise the behaviour of several functions. With the introduction of ranges in C++20 (and of earlier non-standard libraries), the usage of function objects became even more widespread.

Many function objects are extremely simple. Let’s take an implementation of isEven.

auto isEven = [](int i) {return i % 2 == 0;};

2023-08 Mailing Available

By Administrator | Aug 23, 2023 09:54 AM | Tags: None

The 2023-08 mailing of new standards papers is now available.

CopperSpice: Template Parameters

By Ansel Sermersheim | Aug 22, 2023 11:31 AM | Tags: None

New video on the CopperSpice YouTube Channel:

Template Parameters

by Barbara Geller and Ansel Sermersheim

About the video:

Do you know the precise difference between a parameter and an argument? Where can a default argument appear for a template parameter? We have some answers in our newest C++ video.

Please take a look and remember to subscribe.

Using GitHub Actions for Continuous Integration -- Richard Thomson

By Legalize Adulthood | Aug 21, 2023 02:34 PM | Tags: None

Utah C++ Programmers has released a new video:

Using GitHub Actions for Continuous Integration

by Richard Thomson

From the video description:

GitHub actions allow you to set up continuous integration for your C++ project. You can configure, build and test your code in a variety of operating systems and hardware configurations.

This month, Richard Thomson will give us an introduction to GitHub actions for continuous integration of C++ projects. We'll look at how to set up automatic building and testing of code on various repository events, such as commits, pull requests, and so-on.

Some of the topics we will cover are:

• How to configure GitHub actions from scratch
• How to use some continuous integration project templates
• How to run tests
• How to integrate custom build/test environments

https://www.youtube.com/watch?v=1q8BQtvr8sY

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C++23: Syntactic Sugar with Deducing This -- Rainer Grimm

By Blog Staff | Aug 21, 2023 01:57 PM | Tags: None

The Curiously Recurring Template Pattern (CRTP) is a heavily used idiom in C++. It is similarly resistant to understanding as the classic design pattern visitor I presented in my last post: “C++23: Deducing This“.  Thanks to deducing this, we can remove the C and R from the abbreviation.

C++23: Syntactic Sugar with Deducing This

By Rainer Grimm

From the article:

CRTP

The acronym CRTP stands for the C++ idiom Curiously Recurring Template Pattern and denotes a technique in C++ in which a class Derived is derived from a class template Base. The critical point is that Base has Derived as a template argument.

template <typename T>
class Base{
    ...
};

class Derived : public Base<Derived>{
    ...
};

CRTP is typically used to implement static polymorphism. Unlike dynamic polymorphism, static polymorphism happens at compile time and does not require an expensive run-time pointer indirection.