autotools-template

A pair of templates for GNU Autotools, one recursive and one non-recursive. (Non-recursive makes are faster). Simply copy the required folder and start hacking.

Intro

Based on material from https://www.lrde.epita.fr/~adl/autotools.html, namely "Slide nnn" refers to a slide from his presentation. The good stuff only starts at slide 100. Another good resource is http://www.dwheeler.com/autotools/ and he has a list of other resources on his page too.

The Autotools Programs

Main programs you will need to run on day-to-day basis

• autoreconf - run all tools in the right order
• autoscan - look through your source for portability problems and things missing from configure.ac

And some of the others

• autoconf - produces ./configure. autoreconf and autoscan are covered here.
• automake - creates Makefile.in from Makefile.am and configure.ac
• libtool - create libraries

Slide Index

• 100 - good stuff starts
• 129 - the various autotools programs
• 255 - structure of configure.ac
• 269 - checking for programs, continues with other checks such as headers
• 304 - calling AM_INIT_AUTOMAKE, what the params mean
• 322 - building static libraries

Simple setup for recursive automake

First create files, in ROOTDIR:

mkdir src
touch configure.ac
touch Makefile.am
touch src/Makefile.am
touch src/main.cpp

Then build, in ROOTDIR:

autoreconf -i    # reconfigure, install missing things such as NEWS
./configure
make

Development then proceeds simply: when you create a new source file (.cpp or .hpp) add it to src/Makefile.am and type make.

It should not be necessary to re-run autoreconf unless things get really out of whack; make by itself should detect if things need regenerating.

Makefile.am can contain supplementary rules; automake will preserve them in the output files.

You may have one Makefile.am per directory because it is used to generate a file called Makefile and you can only have one of them per directory too. All subsidiary Makefile.ams must be declared in configure.ac.

VPATH Builds (including custom DEBUG builds)

You can arrange for build output to go into any build directory: the configure.ac script detects where it is run from and does a VPATH build automatically. Example:

mkdir builddir && cd builddir
../configure
make

You end up with a bunch of build artifacts in builddir - including a src directory, but that src directory just contains a Makefile and compiler output files, your .cpp and .hpp files remain in the original src folder.

By creating various subdirectories, each with a small shell script to call ../configure with different arguments, you can arrange to create separate builds for debug, profiling, unit tests etc. Normally during development you will want to create a debug build using specific compiler options, but those flags should not be embedded into configure.ac or Makefile.am because they will not be portable. Instead, pass them on the command line using a simple shell script.

Debug builds

The debug folder contains a shell script to build the program with debugging symbols and optimisation turned off. It is specific to g++, which is what I use for development. You will end up with a debugging exe in debug/src/foo.exe.

Release builds

There is no need to create a custom release build. Autotools will do this automatically. Use the install-strip target to strip the compiled exe.

Unit Tests

Autotools has built-in support for running test (including unit tests) via the make check target, and make recheck which just runs the tests that failed on the last run. It is recommended to read Automake - tests before proceeding.

This template stores tests in a tests directory which is a sibling of src.

This still leaves open the question of "which unit testing framework to use?" Of course there are several possibilities. For C++, I think he easiest to use is catch.hpp which is just a single header file which you #include in each test program. The downside is that it is a rather large file which slows down the compilation of the tests, though there are workarounds - see catch - slow compiles This template contains an example of using catch.

Another alternative is Google Test which seems to be a well respected C++ unit testing framework. The downside is that installation is more complicated, but because it is a library compilation should be faster. It also has an adapter to integrate with Autotools (though Catch seems to manage without one). You do not install Google Test globally on your system, you just integrate it into the build system for each project.