Re: Headers only or .o

From: Vinnie Falco (vinnie.falco_at_[hidden])
Date: 2021-03-15 16:42:51

On Mon, Mar 15, 2021 at 9:06 AM Mike via Boost <boost_at_[hidden]> wrote:
> ...

There's a new sheriff in town, an alternative to the traditional
paradigms of header-only and pre-built library. I call it "included
source." It offers the fast compilation of a pre-built library with
the ease of integration of a pre-built library. It doesn't require or
depend on any particular build system. Credit to Christopher Kohlhoff
for using this technique in Boost.ASIO, which I copied in my projects.

Boost.JSON offers this method as an alternative to building a static
or share library. It works like this. Simply place the following line
in exactly one new or existing source file in the program where you
want to use Boost.JSON:

    #include <boost/json/src.hpp>

That's it! This is basically how the static and shared libraries are
built. The build scripts just compile this file src.cpp which has the
include line above:

<https://github.com/boostorg/json/blob/develop/src/src.cpp>

This makes it very easy to add Boost.JSON to your existing project.
You also get the benefit that the optimizer has access to all of the
library's function definitions at once, like a poor man's "global
program optimization." Plus, it makes it easy to use on compiler
explorer:

<https://godbolt.org/z/zPjv9M>

This is the technique that I will be using for all my new libraries.
Furthermore, to reduce compilation times and make things easier to
use, when designing classes and functions I try to avoid templates
where it makes sense to do so. This allows more code to be placed out
of line.

You can read more about this here:

<https://github.com/boostorg/json#header-only>

Thanks