configure.ac

configure.ac will contain all kind of miscellaneous informations about our program. In this step, we will ensure that the system is compatible to our program.

First, we specify metadata informations such as the name and version of the package and the email address of the maintainer or the language used (C++)

	dnl Initialization
	AC_COPYRIGHT([Copyright (C) 2007 Pierre-Alexandre Meyer])
	AC_INIT([set-difference],[1.0],[bug-set_difference@mouraf.org])
	AC_CONFIG_AUX_DIR(build-aux-tools)
	AC_LANG([C++])
	AM_INIT_AUTOMAKE([-Wall -Werror gnu dist-bzip2 1.7])

	dnl Sanity checks.
	AC_CONFIG_SRCDIR([src])

Most of the macros are straightforward to understand. Notice we have required a recent version of automake ($1.7$). With previous versions (e.g. $1.6.3$), one can have problems between macros AM_CONFIG_HEADER and AC_CONFIG_HEADER .

Notice also that we have set the strictness to gnu. This is only a question of the standards the program will respect.

Next step it to specify what is needed to build set_difference : basically a C++ compiler and miscellaneous headers from the STL:

	dnl Checks for programs.
	AS_MESSAGE(Checking required programs...)
	AC_PROG_CXX

	dnl Checks for the right headers.
	AS_MESSAGE(Checking for C++ header files...)
	AC_LANG_ASSERT(C++)
	AC_CHECK_HEADER([iostream],[],
	  [AC_MSG_FAILURE([The standard <iostream> header file could not be found.])])
	AC_CHECK_HEADER([cstdlib],[],
	  [AC_MSG_FAILURE([The standard <cstdlib> header file could not be found.])])
	AC_CHECK_HEADER([vector],[],
	  [AC_MSG_FAILURE([The standard <vector> header file could not be found.])])
	AC_CHECK_HEADER([algorithm],[],
	  [AC_MSG_FAILURE([The standard <algorithm> header file could not be found.])])
	AC_CHECK_HEADER([string.h],[],
	  [AC_MSG_FAILURE([The standard <string.h> header file could not be found.])])

Finally, we provide optional unit tests to ensure the program is working. They may be compiled or not:

	dnl Conditional builds
	AC_ARG_ENABLE(tests,[  --enable-unit-tests            compile unit tests.])