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* Generic builders.

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Eelco Dolstra 2004-11-05 21:11:01 +00:00
parent 3e9d2038b4
commit 5f0300d18c
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89
doc/manual/writing-nix-expressions.xml
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@ -447,7 +447,7 @@ following:
<programlisting>
(import pkgs/system/i686-linux.nix).hello</programlisting>
Call it <filename>test.nix</filename>. Then you can build it without
Call it <filename>test.nix</filename>. You can then build it without
installing it using the command <command>nix-build</command>:
<screen>
@ -501,7 +501,86 @@ run in parallel. Typically this should be the number of CPUs.</para>
<sect2><title>The generic builder</title>
<para>TODO</para>
<para>Recall from <xref linkend='ex-hello-builder' /> that the builder
looked something like this:
<programlisting>
PATH=$perl/bin:$PATH
tar xvfz $src
cd hello-*
./configure --prefix=$out
make
make install</programlisting>
The builders for almost all Unix packages look like this — set up some
environment variables, unpack the sources, configure, build, and
install. For this reason the standard environment provides some Bash
functions that automate the build process. A builder using the
generic build facilities in shown in <xref linkend='ex-hello-builder2'
/>.</para>
<example id='ex-hello-builder2'><title>Build script using the generic
build functions</title>
<programlisting>
buildInputs="$perl" <co id='ex-hello-builder2-co-1' />
. $stdenv/setup <co id='ex-hello-builder2-co-2' />
genericBuild <co id='ex-hello-builder2-co-3' /></programlisting>
</example>
<calloutlist>
<callout arearefs='ex-hello-builder2-co-1'>
<para>The <envar>buildInputs</envar> variable tells
<filename>setup</filename> to use the indicated components as
<quote>inputs</quote>. This means that if a component provides a
<filename>bin</filename> subdirectory, it's added to
<envar>PATH</envar>; if it has a <filename>include</filename>
subdirectory, it's added to GCC's header search path; and so
on.</para>
</callout>
<callout arearefs='ex-hello-builder2-co-2'>
<para>The function <function>genericBuild</function> is defined in
the file <literal>$stdenv/setup</literal>.</para>
</callout>
<callout arearefs='ex-hello-builder2-co-3'>
<para>The final step calls the shell function
<function>genericBuild</function>, which performs the steps that
were done explicitly in <xref linkend='ex-hello-builder' />. The
generic builder is smart enough to figure out whether to unpack
the sources using <command>gzip</command>,
<command>bzip2</command>, etc. It can be customised in many ways;
see <xref linkend='sec-standard-environment' />.</para>
</callout>
</calloutlist>
<para>Discerning readers will note that the
<envar>buildInputs</envar> could just as well have been set in the Nix
expression, like this:
<programlisting>
buildInputs = [perl];</programlisting>
The <varname>perl</varname> attribute can then be removed, and the
builder becomes even shorter:
<programlisting>
. $stdenv/setup
genericBuilder></programlisting>
In fact, <varname>mkDerivation</varname> provides a default builder
that looks exactly like that, so it is actually possible to omit the
builder for Hello entirely.</para>
</sect2>
@ -661,7 +740,7 @@ shortened using the <literal>inherit</literal> keyword. For instance,
-->
<simplesect><title>Lets</title>
<simplesect><title>Let expressions</title>
<para>TODO</para>
@ -691,7 +770,7 @@ shortened using the <literal>inherit</literal> keyword. For instance,
</simplesect>
<simplesect><title><quote>With</quote> expressions</title>
<simplesect><title>With expressions</title>
<para>TODO</para>
@ -723,7 +802,7 @@ shortened using the <literal>inherit</literal> keyword. For instance,
<sect1><title>The standard environment</title>
<sect1 id='sec-standard-environment'><title>The standard environment</title>
<para>TODO</para>