3a9b0bd634
This setup hook modifies a Perl script so that any "-I" flags in its shebang line are rewritten into a "use lib ..." statement on the next line. This gets around a limitation in Darwin, which will not properly handle a script whose shebang line exceeds 511 characters.
224 lines
8.3 KiB
XML
224 lines
8.3 KiB
XML
<section xmlns="http://docbook.org/ns/docbook"
|
||
xmlns:xlink="http://www.w3.org/1999/xlink"
|
||
xml:id="sec-language-perl">
|
||
<title>Perl</title>
|
||
|
||
<para>
|
||
Nixpkgs provides a function <varname>buildPerlPackage</varname>, a generic
|
||
package builder function for any Perl package that has a standard
|
||
<varname>Makefile.PL</varname>. It’s implemented in
|
||
<link
|
||
xlink:href="https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/perl-modules/generic"><filename>pkgs/development/perl-modules/generic</filename></link>.
|
||
</para>
|
||
|
||
<para>
|
||
Perl packages from CPAN are defined in
|
||
<link
|
||
xlink:href="https://github.com/NixOS/nixpkgs/blob/master/pkgs/top-level/perl-packages.nix"><filename>pkgs/top-level/perl-packages.nix</filename></link>,
|
||
rather than <filename>pkgs/all-packages.nix</filename>. Most Perl packages
|
||
are so straight-forward to build that they are defined here directly, rather
|
||
than having a separate function for each package called from
|
||
<filename>perl-packages.nix</filename>. However, more complicated packages
|
||
should be put in a separate file, typically in
|
||
<filename>pkgs/development/perl-modules</filename>. Here is an example of the
|
||
former:
|
||
<programlisting>
|
||
ClassC3 = buildPerlPackage rec {
|
||
name = "Class-C3-0.21";
|
||
src = fetchurl {
|
||
url = "mirror://cpan/authors/id/F/FL/FLORA/${name}.tar.gz";
|
||
sha256 = "1bl8z095y4js66pwxnm7s853pi9czala4sqc743fdlnk27kq94gz";
|
||
};
|
||
};
|
||
</programlisting>
|
||
Note the use of <literal>mirror://cpan/</literal>, and the
|
||
<literal>${name}</literal> in the URL definition to ensure that the name
|
||
attribute is consistent with the source that we’re actually downloading.
|
||
Perl packages are made available in <filename>all-packages.nix</filename>
|
||
through the variable <varname>perlPackages</varname>. For instance, if you
|
||
have a package that needs <varname>ClassC3</varname>, you would typically
|
||
write
|
||
<programlisting>
|
||
foo = import ../path/to/foo.nix {
|
||
inherit stdenv fetchurl ...;
|
||
inherit (perlPackages) ClassC3;
|
||
};
|
||
</programlisting>
|
||
in <filename>all-packages.nix</filename>. You can test building a Perl
|
||
package as follows:
|
||
<screen>
|
||
<prompt>$ </prompt>nix-build -A perlPackages.ClassC3
|
||
</screen>
|
||
<varname>buildPerlPackage</varname> adds <literal>perl-</literal> to the
|
||
start of the name attribute, so the package above is actually called
|
||
<literal>perl-Class-C3-0.21</literal>. So to install it, you can say:
|
||
<screen>
|
||
<prompt>$ </prompt>nix-env -i perl-Class-C3
|
||
</screen>
|
||
(Of course you can also install using the attribute name: <literal>nix-env -i
|
||
-A perlPackages.ClassC3</literal>.)
|
||
</para>
|
||
|
||
<para>
|
||
So what does <varname>buildPerlPackage</varname> do? It does the following:
|
||
<orderedlist>
|
||
<listitem>
|
||
<para>
|
||
In the configure phase, it calls <literal>perl Makefile.PL</literal> to
|
||
generate a Makefile. You can set the variable
|
||
<varname>makeMakerFlags</varname> to pass flags to
|
||
<filename>Makefile.PL</filename>
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
It adds the contents of the <envar>PERL5LIB</envar> environment variable
|
||
to <literal>#! .../bin/perl</literal> line of Perl scripts as
|
||
<literal>-I<replaceable>dir</replaceable></literal> flags. This ensures
|
||
that a script can find its dependencies. (This can cause this shebang line
|
||
to become too long for Darwin to handle; see the note below.)
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
In the fixup phase, it writes the propagated build inputs
|
||
(<varname>propagatedBuildInputs</varname>) to the file
|
||
<filename>$out/nix-support/propagated-user-env-packages</filename>.
|
||
<command>nix-env</command> recursively installs all packages listed in
|
||
this file when you install a package that has it. This ensures that a Perl
|
||
package can find its dependencies.
|
||
</para>
|
||
</listitem>
|
||
</orderedlist>
|
||
</para>
|
||
|
||
<para>
|
||
<varname>buildPerlPackage</varname> is built on top of
|
||
<varname>stdenv</varname>, so everything can be customised in the usual way.
|
||
For instance, the <literal>BerkeleyDB</literal> module has a
|
||
<varname>preConfigure</varname> hook to generate a configuration file used by
|
||
<filename>Makefile.PL</filename>:
|
||
<programlisting>
|
||
{ buildPerlPackage, fetchurl, db }:
|
||
|
||
buildPerlPackage rec {
|
||
name = "BerkeleyDB-0.36";
|
||
|
||
src = fetchurl {
|
||
url = "mirror://cpan/authors/id/P/PM/PMQS/${name}.tar.gz";
|
||
sha256 = "07xf50riarb60l1h6m2dqmql8q5dij619712fsgw7ach04d8g3z1";
|
||
};
|
||
|
||
preConfigure = ''
|
||
echo "LIB = ${db.out}/lib" > config.in
|
||
echo "INCLUDE = ${db.dev}/include" >> config.in
|
||
'';
|
||
}
|
||
</programlisting>
|
||
</para>
|
||
|
||
<para>
|
||
Dependencies on other Perl packages can be specified in the
|
||
<varname>buildInputs</varname> and <varname>propagatedBuildInputs</varname>
|
||
attributes. If something is exclusively a build-time dependency, use
|
||
<varname>buildInputs</varname>; if it’s (also) a runtime dependency, use
|
||
<varname>propagatedBuildInputs</varname>. For instance, this builds a Perl
|
||
module that has runtime dependencies on a bunch of other modules:
|
||
<programlisting>
|
||
ClassC3Componentised = buildPerlPackage rec {
|
||
name = "Class-C3-Componentised-1.0004";
|
||
src = fetchurl {
|
||
url = "mirror://cpan/authors/id/A/AS/ASH/${name}.tar.gz";
|
||
sha256 = "0xql73jkcdbq4q9m0b0rnca6nrlvf5hyzy8is0crdk65bynvs8q1";
|
||
};
|
||
propagatedBuildInputs = [
|
||
ClassC3 ClassInspector TestException MROCompat
|
||
];
|
||
};
|
||
</programlisting>
|
||
</para>
|
||
|
||
<para>
|
||
On Darwin, if a script has too many
|
||
<literal>-I<replaceable>dir</replaceable></literal> flags in its first line
|
||
(its “shebang line”), it will not run. This can be worked around by calling
|
||
the <literal>shortenPerlShebang</literal> function from the
|
||
<literal>postInstall</literal> phase:
|
||
<programlisting>
|
||
{ stdenv, buildPerlPackage, fetchurl, shortenPerlShebang }:
|
||
|
||
ImageExifTool = buildPerlPackage {
|
||
pname = "Image-ExifTool";
|
||
version = "11.50";
|
||
|
||
src = fetchurl {
|
||
url = "https://www.sno.phy.queensu.ca/~phil/exiftool/Image-ExifTool-11.50.tar.gz";
|
||
sha256 = "0d8v48y94z8maxkmw1rv7v9m0jg2dc8xbp581njb6yhr7abwqdv3";
|
||
};
|
||
|
||
buildInputs = stdenv.lib.optional stdenv.isDarwin shortenPerlShebang;
|
||
postInstall = stdenv.lib.optional stdenv.isDarwin ''
|
||
shortenPerlShebang $out/bin/exiftool
|
||
'';
|
||
};
|
||
</programlisting>
|
||
This will remove the <literal>-I</literal> flags from the shebang line,
|
||
rewrite them in the <literal>use lib</literal> form, and put them on the next
|
||
line instead. This function can be given any number of Perl scripts as
|
||
arguments; it will modify them in-place.
|
||
</para>
|
||
|
||
<section xml:id="ssec-generation-from-CPAN">
|
||
<title>Generation from CPAN</title>
|
||
|
||
<para>
|
||
Nix expressions for Perl packages can be generated (almost) automatically
|
||
from CPAN. This is done by the program
|
||
<command>nix-generate-from-cpan</command>, which can be installed as
|
||
follows:
|
||
</para>
|
||
|
||
<screen>
|
||
<prompt>$ </prompt>nix-env -i nix-generate-from-cpan
|
||
</screen>
|
||
|
||
<para>
|
||
This program takes a Perl module name, looks it up on CPAN, fetches and
|
||
unpacks the corresponding package, and prints a Nix expression on standard
|
||
output. For example:
|
||
<screen>
|
||
<prompt>$ </prompt>nix-generate-from-cpan XML::Simple
|
||
XMLSimple = buildPerlPackage rec {
|
||
name = "XML-Simple-2.22";
|
||
src = fetchurl {
|
||
url = "mirror://cpan/authors/id/G/GR/GRANTM/${name}.tar.gz";
|
||
sha256 = "b9450ef22ea9644ae5d6ada086dc4300fa105be050a2030ebd4efd28c198eb49";
|
||
};
|
||
propagatedBuildInputs = [ XMLNamespaceSupport XMLSAX XMLSAXExpat ];
|
||
meta = {
|
||
description = "An API for simple XML files";
|
||
license = with stdenv.lib.licenses; [ artistic1 gpl1Plus ];
|
||
};
|
||
};
|
||
</screen>
|
||
The output can be pasted into
|
||
<filename>pkgs/top-level/perl-packages.nix</filename> or wherever else you
|
||
need it.
|
||
</para>
|
||
</section>
|
||
|
||
<section xml:id="ssec-perl-cross-compilation">
|
||
<title>Cross-compiling modules</title>
|
||
|
||
<para>
|
||
Nixpkgs has experimental support for cross-compiling Perl modules. In many
|
||
cases, it will just work out of the box, even for modules with native
|
||
extensions. Sometimes, however, the Makefile.PL for a module may
|
||
(indirectly) import a native module. In that case, you will need to make a
|
||
stub for that module that will satisfy the Makefile.PL and install it into
|
||
<filename>lib/perl5/site_perl/cross_perl/${perl.version}</filename>. See the
|
||
<varname>postInstall</varname> for <varname>DBI</varname> for an example.
|
||
</para>
|
||
</section>
|
||
</section>
|