OpenMP on High Sierra

Building OpenMP code is actually possible using Apple Clang that comes default with macOS’s Xcode! Although Apple does not build the OpenMP library, the compiler still supports it. In this post, I demonstrate the procedure necessary to include OpenMP in your build, both with the new support in CMake 3.12, as well as how it would be done without it.

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Announcing GooFit 2.0

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.

GooFit on GitHubGooFit webpage • API documentation

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Announcing CLI11 Version 1.0

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.

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Perfect forwarding for methods

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.

Lua Environment Modules

This is a guide to setting up Lmod (lua environment modules) on a CentOS system. I’ve used a similar procedure to set them up on a Mac, as well, so this is still a useful guide to the workings of Lmod if you use a different system; mostly paths will change. On a Mac, you’ll want to install Lmod from the science tap in brew. There are several good pages covering environment modules (TCL version), but not many that use the newer Lua syntax. This document aims to fill that roll.

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GoogleTest and CMake

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+.

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