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- 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.
- What gives?
-
- It turns out that we've already covered all the material to make a library in
- the page on creating a :doc:`Hello, world! executable <hello-world>`. 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 expressly *not* considered to be part of a
- library, as it is specifically designated to be an application entry point,
- and source files of such kind are not part of a library.
-
- Before continuing on, note the following about creating a library that wasn't
- specifically addressed in the prior example:
-
- #. 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.
- #. ``dds`` 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 :ref:`pkgs.lib-roots` in the layout
- 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.
-
- .. seealso::
- Like flossing, we all know we *should* be writing tests, but it can be such
- a hassle. Fortunately, ``dds`` makes it simple. Read on to:
- :doc:`hello-test`.
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