A Hello, World Library

Creating a single application is fun, but what if we want to create code that we can distribute and reuse across other packages and projects? That’s what libraries are for.

You may notice something strange: This page is much shorter than the previous: It turns out that we’ve already covered all the material to make a library in the page on creating a Hello, world! executable. As soon as we created the strings.hpp file, our project had become a library. When we added a strings.cpp file to accompany it, our library became a compiled library.

The hello-world.main.cpp file is an application source file associated with the library but it will not be linked with the library itself, as it is specifically designated to be an application entry point.

Before continuing on, note the following about creating a library that wasn’t specifically addressed in the prior example:

  1. The source roots of a library are added to the compiler’s #include search-path. In our example, this is only the src/ directory of the project.

  2. bpt also supports a top-level directory named include/. Both include/ and src/ may be present in a single library, but there are some important differences. Refer to Source Root Kinds in the guide. #. A single library root may contain any number of applications defined in .main files, but a library root will correspond to exactly one library. Defining additional libraries requires additional packages or adding multiple library roots to a single package.

See also

Like flossing, we all know we should be writing tests, but it can be such a hassle. Fortunately, bpt makes it simple. Read on to: A Hello, World Test.