Programming

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.

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+.

This is a simple explanation of the asyncio module and new supporting language features in Python 3.5. Even though the new keywords async and await are new language constructs, they are mostly¹ useless without an event loop, and that is supplied in the standard library as asyncio. Also, you need awaitable functions, which are only supplied by asyncio (or in the growing set of async libraries, like asyncssh, quamash etc.).

This is a simple example to show how Asyncio works without using Asyncio itself, instead using a basic and poorly written event loop. This is only meant to give a flavor of what Asyncio does behind the curtains. I’m avoiding most details of the library design, like callbacks, just to keep this simple. Since this is written as an illustration, rather than real code, I’m going to dispense with trying to keep it 2.7 compatible.

I realized that CRY did not have a CMake based install option, so including it in a GEANT4 cmake project might not be obvious. This is how you would do it in your CMakeLists.txt:

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 “recommended” 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.

Slots seem to be poorly documented. What they do is simple, but whether they are used is tricky. This is a little mini-post on slots.

This is a quick tutorial over the basics of what metaclasses do.

The Metaclass

Metaclasses, while seemingly a complex topic, really just do something very simple. They control what happens when you have code that turns into a class object. The normal place they are executed is right after the class statement. Let’s see that in action by using print as our metaclass.