Cpp on ISciNumPy.dev

C++23

henryfs@princeton.edu (Henry Schreiner) — Mon, 23 Oct 2023 11:00:00 -0400

C++23 is complete and pretty much finalized, so let’s explore the new features in C++, from a data science point of view. This is not as large of a release as C++20 or C++11, but it’s still a hefty release with lots of nice new features - larger than C++17.

Some of the major new features are building on themes from C++20, such as vastly expanded ranges and views, more constexpr/consteval, module support for the standard library, std::print to supplement std::format, and a std::generator to support coroutines. There are also several general features, lambdas and classes get along much better now, there are new preprocessor additions (!), a stacktrace library, flat maps/sets, and new std::optional monadics, deducing this, and many various additions.

Announcing CLI11 2.0

henryfs@princeton.edu (Henry Schreiner) — Wed, 14 Jul 2021 14:34:02 -0400

CLI11, a powerful library for writing beautiful command line interfaces in C++11, has been updated to 2.0. A lot of deprecated things have been removed, and there was a lot of cleanup under-the-hood; making CLI11 simpler. A few defaults have changed slightly, like better TOML support by default.

CLI11 does a better job than ever understanding any sort of container you provide - complex numbers are natively supported, along with atomic types. A long requested feature, simple version flags, has been added. Subcommands are more customizable. And there have been quite a few bugfixes for rare issues.

C++20

henryfs@princeton.edu (Henry Schreiner) — Sat, 20 Jul 2019 22:42:21 -0400

The final meeting for new features in C++ is over, so let’s explore the new features in C++, from a data science point of view. This is the largest release of C++ since C++11, and when you consider C++14 and C++17 to be interim releases, the entire 9 year cycle is possibly the largest yet! It may not feel quite as massive as C++11, since we didn’t have interim releases for C++11 and because C++11 is a much more complete, useful language than C++03, but this is still a really impactful release! This is also the first version to include every major feature from Bjarne Stroustrup’s “The design and Evolution of C++”, also known as D&E, from 1994!

Let’s look at the major new features, as well as collections of smaller ones.

Binding Minuit2

henryfs@princeton.edu (Henry Schreiner) — Sat, 07 Jul 2018 21:00:00 +0200

Let’s try a non-trivial example of a binding: Minuit2 (6.14.0 standalone edition).

Tools to Bind to Python

henryfs@princeton.edu (Henry Schreiner) — Sat, 07 Jul 2018 21:00:00 +0200

This was originally given as a PyHEP 2018 talk, It is designed to be interactive, and can be run in SWAN if you have a CERN account. If you want to run it manually, just download the repository: github.com/henryiii/pybindings_cc. It is easy to run in Anaconda.

Announcing CLI11 1.6

henryfs@princeton.edu (Henry Schreiner) — Wed, 27 Jun 2018 14:44:40 +0200

CLI11, a powerful library for writing beautiful command line interfaces in C++11, has been updated to 1.6, the largest update ever. CLI11 output is more customizable than ever, and has a better functionality separation under the hood.

CLI11 has had the formatting system completely redesigned, with minor or complete customization of the output possible. Configuration files reading and writing also can be configured; a new example with json instead of ini formatting is included. Validators (finally) have custom help output, as well. Many odd corner cases have been made possible, such as interleaving options.

Announcing GooFit 2.1

henryfs@princeton.edu (Henry Schreiner) — Thu, 07 Dec 2017 03:20:00 -0500

GooFit 2.1 introduces the full-featured Python bindings to GooFit. These bindings mimic the C++ usage of GooFit, including bindings for all PDFs, and also provide NumPy-centric conversions, live Jupyter notebook printing, pip install, and more. Most of the examples in C++ are provided in Python form, as well.

Several other API changes were made. Observables are now distinguished from Variables and provided as a separate class. Both these classes are now passed around by copy everywhere.¹ The three and four body amplitude classes have been refactored and simplified. OpenMP is now supported via homebrew on macOS; GooFit is one of the only packages that currently can build with OpenMP on the default macOS compiler. Eigen is now available, and CLI11 has been updated to version 1.3.

GooFit 2.1 will receive continuing support while development on GooFit 2.2 presses on with a new indexing scheme for PDFs.

Include What You Use

henryfs@princeton.edu (Henry Schreiner) — Tue, 05 Dec 2017 14:06:35 -0500

Include-what-you-use is a promising little tool for cleaning up a codebase. It didn’t end up working for the use I had for it, but it still could be useful. Here is a quick guideline on installing it on macOS.

Comparing CLI11 and Boost PO

henryfs@princeton.edu (Henry Schreiner) — Sun, 03 Dec 2017 16:31:50 -0500

CLI11 started years ago as a set of tools built on Boost Program Options (PO), and has since matured into the powerful, easy-to-use stand-alone library it is available today. If you would like to see the original inspiration for CLI11, look at Program.hpp in CLI11 0.1. The rest of the post will focus on a comparison between making a CLI app in the two libraries. I am going to assume that you are preparing fairly basic but non-trivial programs in the following comparison.

TL;DR: CLI11 is more concise, and provides more control with better defaults in many cases, but was inspired by Boost PO.

Announcing CLI11 1.3

henryfs@princeton.edu (Henry Schreiner) — Fri, 01 Dec 2017 09:03:50 -0500

CLI11, a powerful library for writing beautiful command line interfaces in C++11, has been updated to 1.3, the largest update ever. CLI11 is more powerful than ever, and has simpler and more consistent parsing under the hood.

This version focused on refactoring several key systems to ensure correct behavior in the interaction of different settings. Most caveats about features only working on the main App have been addressed, and extra arguments have been reworked. Inheritance of defaults makes configuring CLI11 much easier without having to subclass. Policies add new ways to handle multiple arguments to match your favorite CLI programs. Error messages and help messages are better and more flexible. Several bugs and odd behaviors in the parser have been fixed.

Announcing GooFit 2.0

henryfs@princeton.edu (Henry Schreiner) — Thu, 08 Jun 2017 17:54:00 -0700

The next version of the premier CUDA/OpenMP fitting program for HEP analysis, GooFit 2.0, has been released. GooFit is now easy to build on a wide variety of Unix systems, and supports debuggers and IDEs. GooFit is faster, has unit tests, and working examples. More PDFs and examples have been added, as well as newly released example datasets that are downloaded automatically. GooFit now has built in support for MPI, and can use that to deploy to multiple graphics cards on the same machine. A new command line parser (CLI11) and drastically improved logging and errors have made code easier to write and debug. Usage of GooFit specific terminology is now reduced, using standard Thrust or CUDA terms when possible, lowering the barrier for new developers. A new Python script has been added to assist users converting from pre 2.0 code.

The file structure of GooFit and the build system have been completely revamped. The fake nvcc features have been removed, as have the rootstuff copies of ROOT classes. PDFs are now organized by type and compile and link separately. Multiple PDF caching support has improved. The build system now uses CMake and manages external libraries.

A new feature of the CMake build system is GooFit Packages, which are complete packages that can be added to GooFit and built, allowing analysis code to live in a separate location from GooFit, rather than the old method of simply forking GooFit and adding your analysis manually. A GooFit Package can be made into an example trivially. See this package for an example.

GooFit 2.0 will receive continuing support while development on GooFit 2.1 presses on.

Links

GooFit on GitHub • GooFit webpage • API documentation

Announcing CLI11 Version 1.0

henryfs@princeton.edu (Henry Schreiner) — Thu, 01 Jun 2017 14:05:00 -0700

CLI11, a powerful library for writing command line interfaces in C++11, has just been released. There are no requirements beyond C++11 support (and even <regex> support not required). It works on Mac, Linux, and Windows, and has 100% test coverage on all three systems. You can simply drop in a single header file (CLI11.hpp available in releases) to use CLI11 in your own application. Other ways to integrate it into a build system are listed in the README.

The library was inspired the Python libraries Plumbum and Click, and incorporates many of their user friendly features. The library is extensively documented, with a friendly introduction, a tutorial filled (in progress) GitBook, and more technical API docs.

Perfect forwarding for methods

henryfs@princeton.edu (Henry Schreiner) — Fri, 17 Mar 2017 10:43:00 -0700

I often see perfect forwarding listed for constructor arguments, but not usually for functions with a return or methods. Here is my solution for an method method of class Cls:

template<typename ...Args>
static auto method(Cls* cls, Args && ...args)
 -> typename std::result_of<decltype(&Cls::method)(Cls, Args...)>::type {
 return cls->method(std::forward<Args>(args)...);
}

This is useful if you want to call protected classes from a “helper” friend class, for example, to expose them to tests without having to require GoogleTest/GoogleMock to be available for regular users.

C++17

henryfs@princeton.edu (Henry Schreiner) — Sat, 10 Sep 2016 08:30:00 +0200

The every-three-year cycle has changed the development of C++; we are now getting consistent releases somewhere in-between the major and minor releases of old. The 2017 release may be called minor by some, with a huge portion of the planned improvements being pushed back another 3-6 years, but there were several substantial changes in useful areas; it is much more impactful than C++14, for example. This almost feels like a lead-in release to C++20.

The std::variant, std::optional, and std::any additions to the standard library are huge, and can restructure the way you program (and are available for older C++ releases through Boost and other libraries).

C++14

henryfs@princeton.edu (Henry Schreiner) — Fri, 09 Sep 2016 08:30:00 +0200

Unlike C++11, this is a minor release, focused mostly on improvements on top of C++11 changes, with very little that one could call “new”. C++14 feels a little more natural than C++11 by expanding the usage of features and implementing common sense additions that were missed in the original C++11 release. There were also quite a few bug fixes; several of these were backported into C++11 mode in compilers.

Also, while C++11 is always available in ROOT 6, C++14 requires a flag and compatible compiler, so C++14 features are often unavailable. The Conda-Forge ROOT package has C++17 enabled.

C++11

henryfs@princeton.edu (Henry Schreiner) — Thu, 08 Sep 2016 08:30:00 +0200

C++11 was the largest change ever made to C++; and due to the changed release schedule, probably will remain the largest single change. It is a well thought out, mostly backward-compatible change that can cause you to completely rethink the way you write code in C++. It is best thought of as almost a new language, a sort of (C++)++ language. There are too many changes to list here, and there are excellent resources available, so this is meant to just give you a taste of some of the most useful changes.

Many of the features work best together, or are related. There already are great resources for learning about C++11 (listed at the bottom of this lesson), and C++11 is already in use in most software. Therefore, the remainder of this lesson will cover a few of the common idioms in C++11 that a programmer experienced with the older C++ might not immediately think of.

GoogleTest and CMake

henryfs@princeton.edu (Henry Schreiner) — Fri, 25 Mar 2016 16:12:00 -0700

This is a quick recipe for setting up CMake to use googletest in your projects. First, make a tests folder in the root of your project. Then, add add_subdirectory(tests) to your CMakeLists.txt, after you’ve finished adding the libraries in your project. Note that the way I’ve written this probably requires CMake 3.4+.

GTest Submodule

henryfs@princeton.edu (Henry Schreiner) — Wed, 07 Oct 2015 06:43:00 -0700

Note: There is a better way to do this described here.

If you’ve ever tried apt-get or brew to try to install gtest, you are probably familiar with the fact that gtest is not “recommend” for global install on your system. As an alternative, the recommendation is that you make it part of your project. The process for making gtest part of your project, however, is not well documented, at least for modern git projects. What follows is the procedure I used to do so.