Introducing 'dnl configure.ac'

'dnl configure.ac' is a configuration file used by the Autoconf tool to generate a Makefile that can be used to build a software project. This file is typically located in the root directory of the project and contains a set of macros and options that define the build system for the project.

What is Autoconf?

Autoconf is a tool that helps automate the configuration process for software projects. It allows developers to write a single configuration file (configure.ac) that can be used to generate a configure script. This script can then be used to build and install the software on different platforms and architectures.

What is the purpose of 'dnl configure.ac'?

The main purpose of 'dnl configure.ac' is to provide a set of macros and options that define the build system for a software project. These macros and options are used by Autoconf to generate a Makefile that can be used to build the project.

What is a macro?

A macro is a set of commands that can be used to define a specific aspect of the build system. For example, a macro can be used to define the location of header files or shared libraries that are required to build the project. Macros are defined in 'dnl configure.ac' using the AC_DEFUN macro.

What is an option?

An option is a command line argument that can be used to modify the behavior of the configure script. Options can be used to enable or disable certain features of the software, or to configure the build system for different platforms and architectures. Options are defined in 'dnl configure.ac' using the AC_ARG_* macros.

# Example of a macro and an option in 'dnl configure.ac'

AC_DEFUN([HELLO_WORLD], [
  AC_MSG_NOTICE([Hello, world!])
])

AC_ARG_ENABLE([feature], [AC_HELP_STRING([--enable-feature], [Enable a cool feature])], [
  AC_DEFINE([ENABLE_FEATURE], [1], [Enable or disable a cool feature])
])

Overall, 'dnl configure.ac' is an essential file for configuring and building software projects using Autoconf. By defining macros and options in this file, developers can create a flexible and portable build system that can be used across different platforms and architectures.