<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>1.2. System definition files</title><link rel="stylesheet" href="ecl.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.75.2"><link rel="home" href="index.html" title="The ECL manual"><link rel="up" href="ch16.html" title="Chapter 1. System building"><link rel="prev" href="ch16.html" title="Chapter 1. System building"><link rel="next" href="ch16s03.html" title="1.3. Practical examples"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">1.2. System definition files</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch16.html">Prev</a> </td><th width="60%" align="center">Chapter 1. System building</th><td width="20%" align="right"> <a accesskey="n" href="ch16s03.html">Next</a></td></tr></table><hr></div><div class="section" title="1.2. System definition files"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="ext.asdf.sdf"></a>1.2. System definition files</h2></div></div></div><p>A System Definition File, or just <span class="emphasis"><em>system</em></span>, is the
lisp equivalent of a makefile in the Unix world: it contains a list of source
files which are to be loaded or compiled, and dependencies among them ("load
source <code class="filename">file1.lsp</code> before compiling
<code class="filename">file2.lsp</code>", etc).</p><p>It is difficult to tell about the Lisp Machines history, but probably
the first most popular system definition format was called
<span class="application">mk-defsystem</span> or simply
<span class="application">defsystem</span>. Written by Mark Kantrowitz [<a class="xref" href="bi01.html#bib.mk-defsystem">mk-defsystem</a>], this library now lives in the <a class="ulink" href="https://sourceforge.net/projects/clocc/" target="_top">CLOCC</a> repository and is
actively maintained. <span class="application">ECL</span> ships with a copy of the version 3.x which
fortunately has no customizations. You can load this copy by issuing
<code class="code">(require 'defsystem)</code> from the lisp toplevel.</p><p>However, in the last years, Another System Definition Facility known as
<span class="application">ASDF</span> has become even more popular in the Common Lisp world. This new
format simplifies writing extensions to handle new kind of source files and
integrates very well with the package management utility known as
<span class="application">ASDF-install</span>. <span class="application">ASDF</span> has a slightly different
syntax from <span class="application">mk-defsystem 3.0</span>, but because of
reasons of popularity and better integration with <span class="application">ECL</span>, in this manual we
have focused on this particular library.</p><p>A simple <span class="application">ASDF</span> definition looks as follows:</p><pre class="programlisting">
(defsystem test
:source-pathname "~/src/test/"
:source-extension "lisp"
:components ((:module file1
:source-pathname "")
(:module file2
:source-pathname ""
:depends-on (file1))))</pre><p>This example consists of two files, <code class="filename">file1.lisp</code> and
<code class="filename">file2.lisp</code>, located in
<code class="filename">~/src/test/</code>. When compiling these files,
<code class="filename">file1.lisp</code> will be processed before
<code class="filename">file2.lisp</code>, because the second depends on the former
one. There are more complex rules that allow a system to depend on others,
and to contain other kind of files, such as C or Java binaries. For further
information we recommend reading <a class="ulink" href="http://constantly.at/lisp/asdf/" target="_top">the online manual</a>.</p><p>You can load <span class="application">ASDF</span> on a running <span class="application">ECL</span> using a single lisp statement
<code class="code">(require 'asdf)</code>. Once loaded, <span class="application">ASDF</span> will extend the function
<code class="function">require</code> to recognize and load libraries that are placed
in standard locations or which have been registered with <span class="application">ASDF</span> itself. The
following sections describe other features of <span class="application">ASDF</span> which are specific to
<span class="application">ECL</span> and related to the code building and shipping mechanisms introduced
before.</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch16.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch16.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch16s03.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 1. System building </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 1.3. Practical examples</td></tr></table></div></body></html>
