configure documentation
-----------------------


These are the documentation notes for configure. The configure project is a
Makefiles generator. It uses project description files to propose simple
Makefiles. It is intended to keep generated code as simple as possible.

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Table of contents
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I. Overview of configure
1.1 What is configure
1.2 Who should use configure
1.3 Who should not use configure
1.4 Why use configure

II. Using configure
2.1 configure usage
2.2 Project configuration
2.3 Targets definition
2.4 Migrating to configure

III. Getting further
3.1 Current caveats
3.2 Planned improvements

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I. Overview of configure

1.1 What is configure
configure generates Makefiles needed in an entire project. Instead of trying
every little trick to let it work in a number of potential uses, it sticks to
the simplest possible code generation. Consequently, it will mostly be useful
for projects running on UNIX platforms first.

1.2 Who should use configure
Every software developer could gain using configure. However, due to its
intentional simplicity, it may not be appropriate to use along with code
compilation on some non-portable platforms.
Of course an advanced user, trying to modify a given project Makefile on his
platform, inside a project using configure may have to use configure too.

1.3 Who should not use configure
configure will certainly not be appropriate alone for cross-plaform projects,
and maybe not for big projects. However one should be able to keep its
configuration files inside a project without creating any trouble for potential
other Makefile files generators.

1.4 Why use configure
configure has been created to be efficient at writing simple and compliant
Makefiles for small to big software development projects. It should be useful:
- for people learning software development using Makefiles;
- for developers of some small to big projects;
- for developers concerned by the readability and efficiency of their
  Makefiles.

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II. Using configure

2.1 configure usage
The configure utility may be invoked from the command line this way:
$ configure [-nv][directory]

The "-n" option just parses the project definition files, without actually
re-generating the Makefiles.
The "-v" option gives information about the progress of the operation.

It then processes the current directory, or one given at the command line,
according to the project configuration files.

2.2 Project configuration
This file should be found in every project directory. It must be named
"project.conf". It is organized in sections, and string variables. Section names
are written on their own line, between brackets (eg "[section]"). Variables are
given on their own line too, like this:
variable=value
Configuration files may be commented, comment lines being prepended with a
hash sign "#".
The significant variables are the following:
- in the default section (has an empty name, eg "[]" in the file)
  * subdirs: subdirectories to look for too
  * cflags_force: CFLAGS to force globally
  * cflags: optional global CFLAGS
  * ldflags_force: LDFLAGS to force globally
  * ldflags: optional global LDFLAGS
  * targets: targets to handle in the Makefile
  * dist: additional files to include in a source archive
- in sections named like the target they define:
  * type (mandatory): type of the target (eg "binary", "library", "object", ...)
  * cflags: additional CFLAGS for this target
  * ldflags: additional LDFLAGS for this target
  * sources: source files to compile

2.3 Targets definitions
The following target types are currently supported:
- "binary": produces binary files, linked from every object file produced with
  their source files.
- "library": produces a static and a shared version of the target, linked from
  every object file produced with their source files, and respectively appending
  ".a" and ".so" extensions to the target name.
- "object": produces a binary object file from the given source.

2.4 Migrating to configure
You may first create all necessary "project.conf" files with the subdirectories
definitions. Then for every binary or library built, specify the adequate target
along with its section.
When migrating from automake/autoconf, the existing subdirectories are defined
in the "Makefile.am" files, in the "SUBDIRS" variable. The binary targets are
defined in the same file, as the "bin_PROGRAMS" variable, each declined to
"program_SOURCES" for their respective source files.

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III. Getting further

3.1 Current caveats
- configure is not user-proof when necessary development files are not available
  (relies on appropriate third-party programs error messages, eg
  "project-config" or "pkgconfig")

3.2 Planned improvements
- run-time system detection or selection;
- generation of the Makefiles altered acordingly;
- tweakable installation path.
