Provided by: libextutils-autoinstall-perl_0.64-2_all 
NAME
ExtUtils::AutoInstall - Automatic install of dependencies via CPAN
VERSION
This document describes version 0.63 of ExtUtils::AutoInstall, released September 12,
2005.
SYNOPSIS
In Makefile.PL, with Module::Install available on the author's system:
use inc::Module::Install;
name ('Joe-Hacker');
abstract ('Perl Interface to Joe Hacker');
author ('Joe Hacker <joe@hacker.org>');
include ('ExtUtils::AutoInstall');
requires ('Module0'); # mandatory modules
features (
-config => {
make_args => '--hello', # option(s) for CPAN::Config
force => 1, # pseudo-option to force install
do_once => 1, # skip previously failed modules
},
'Feature1' => [
'Module2' => '0.1',
],
'Feature2' => [
'Module3' => '1.0',
],
);
auto_install();
&WriteAll;
Invoking the resulting Makefile.PL:
% perl Makefile.PL # interactive behaviour
% perl Makefile.PL --defaultdeps # accept default value on prompts
% perl Makefile.PL --checkdeps # check only, no Makefile produced
% perl Makefile.PL --skipdeps # ignores all dependencies
% perl Makefile.PL --testonly # don't write installation targets
Note that the trailing 'deps' of arguments may be omitted, too.
Using "--defaultdeps" will make Makefile.PL behave similarly to a regular Makefile.PL file
with "PREREQ_PM" dependencies.
One can use environment variables (see "ENVIRONMENT") below to set a default behavior
instead of specifying it in the command line for every invocation of Makefile.PL.
Using make (or nmake):
% make [all|test|install] # install dependencies first
% make checkdeps # same as the --checkdeps above
% make installdeps # install dependencies only
DESCRIPTION
ExtUtils::AutoInstall lets module writers to specify a more sophisticated form of
dependency information than the "PREREQ_PM" option offered by ExtUtils::MakeMaker.
This module works best with the Module::Install framework, a drop-in replacement for
MakeMaker. However, this module also supports Makefile.PL files based on MakeMaker; see
"EXAMPLES" for instructions.
Prerequisites and Features
Prerequisites are grouped into features, and the user could choose yes/no on each one's
dependencies; the module writer may also supply a boolean value via "-default" to specify
the default choice.
The Core Features marked by the name "-core" will double-check with the user, if the user
chooses not to install the mandatory modules. This differs from the pre-0.26 'silent
install' behaviour.
Starting from version 0.27, if "-core" is set to the string "all" (case-insensitive),
every feature will be considered mandatory.
The dependencies are expressed as pairs of "Module" => "version" inside an array
reference. If the order does not matter, and there are no "-default", "-tests" or
"-skiptests" directives for that feature, you may also use a hash reference.
The Installation Process
Once ExtUtils::AutoInstall has determined which module(s) are needed, it checks whether
it's running under the CPAN shell and should therefore let CPAN handle the dependency.
Finally, the "WriteMakefile()" is overridden to perform some additional checks, as well as
skips tests associated with disabled features by the "-tests" option.
The actual installation happens at the end of the "make config" target; both "make test"
and "make install" will trigger the installation of required modules.
If it's not running under CPAN, the installer will probe for an active connection by
trying to resolve the domain "cpan.org", and check for the user's permission to use CPAN.
If all went well, a separate
CPAN instance is created to install the required modules.
If you have the CPANPLUS package installed in your system, it is preferred by default over
CPAN; it also accepts some extra options (e.g. "-target => 'skiptest', -skiptest => 1" to
skip testing).
All modules scheduled to be installed will be deleted from %INC first, so
ExtUtils::MakeMaker will check the newly installed modules.
Additionally, you could use the "make installdeps" target to install the modules, and the
"make checkdeps" target to check dependencies without actually installing them; the "perl
Makefile.PL --checkdeps" command has an equivalent effect.
If the Makefile.PL itself needs to use an independent module (e.g. Acme::KillarApp, v1.21
or greater), then use something like below:
BEGIN {
require ExtUtils::AutoInstall;
# the first argument is an arrayref of the -config flags
ExtUtils::AutoInstall->install([], 'Acme::KillerApp' => 1.21);
}
use Acme::KillerApp 1.21;
ExtUtils::AutoInstall->import(
# ... arguments as usual ...
);
Note the version test in the use clause; if you are so close to the cutting edge that
Acme::KillerApp 1.20 is the latest version on CPAN, this will prevent your module from
going awry.
User-Defined Hooks
User-defined pre-installation and post-installation hooks are available via
"MY::preinstall" and "MY::postinstall" subroutines, as shown below:
# pre-install handler; takes $module_name and $version
sub MY::preinstall { return 1; } # return false to skip install
# post-install handler; takes $module_name, $version, $success
sub MY::postinstall { return; } # the return value doesn't matter
Note that since ExtUtils::AutoInstall performs installation at the time of "use" (i.e.
before perl parses the remainder of Makefile.PL), you have to declare those two handlers
before the "use" statement for them to take effect.
If the user did not choose to install a module or it already exists on the system, neither
of the handlers is invoked. Both handlers are invoked exactly once for each module when
installation is attempted.
"MY::preinstall" takes two arguments, $module_name and $version; if it returns a false
value, installation for that module will be skipped, and "MY::postinstall" won't be called
at all.
"MY::postinstall" takes three arguments, $module_name, $version and $success. The last
one denotes whether the installation succeeded or not: 1 means installation completed
successfully, 0 means failure during install, and "undef" means that the installation was
not attempted at all, possibly due to connection problems, or that module does not exist
on CPAN at all.
Customized "MY::postamble"
Starting from version 0.43, ExtUtils::AutoInstall supports modules that require a
"MY::postamble" subroutine in their Makefile.PL. The user-defined "MY::postamble", if
present, is responsible for calling "ExtUtils::AutoInstall::postamble" and include the
output in its return value.
For example, the DBD::* (database driver) modules for the Perl DBI are required to include
the postamble generated by the function "dbd_postamble", so their Makefile.PL may contain
lines like this:
sub MY::postamble {
return &ExtUtils::AutoInstall::postamble . &dbd_postamble;
}
Note that the ExtUtils::AutoInstall module does not export the "postamble" function, so
the name should always be fully qualified.
CAVEATS
ExtUtils::AutoInstall will add "UNINST=1" to your make install flags if your effective uid
is 0 (root), unless you explicitly disable it by setting CPAN's "make_install_arg"
configuration option (or the "makeflags" option of CPANPLUS) to include "UNINST=0". This
may cause dependency problems if you are using a fine-tuned directory structure for your
site. Please consult "FAQ" in CPAN for an explanation in detail.
If either version or Sort::Versions is available, they will be used to compare the
required version with the existing module's version and the CPAN module's. Otherwise it
silently falls back to use cmp. This may cause inconsistent behaviours in pathetic
situations.
NOTES
Since this module is needed before writing Makefile, it makes little use as a CPAN module;
hence each distribution must include it in full. The only alternative I'm aware of,
namely prompting in Makefile.PL to force user install it (cf. the Template Toolkit's
dependency on AppConfig) is not very desirable either.
The current compromise is to add the bootstrap code listed in the "SYNOPSIS" before every
script, but that does not look pretty, and will not work without an Internet connection.
Since we do not want all future options of ExtUtils::AutoInstall to be painfully detected
manually like above, this module provides a bootstrapping mechanism via the "-version"
flag. If a newer version is needed by the Makefile.PL, it will go ahead to fetch a new
version, reload it into memory, and pass the arguments forward.
If you have any suggestions, please let me know. Thanks.
ENVIRONMENT
ExtUtils::AutoInstall uses a single environment variable, "PERL_EXTUTILS_AUTOINSTALL". It
is taken as the command line argument passed to Makefile.PL; you could set it to either
"--defaultdeps" or "--skipdeps" to avoid interactive behaviour.
EXAMPLES
Using MakeMaker with AutoInstall
To use this module with ExtUtils::MakeMaker, first make a inc/ExtUtils/ subdirectory in
the directory containing your Makefile.PL, and put a copy this module under it as
inc/ExtUtils/AutoInstall.pm. You can find out where this module has been installed by
typing "perldoc -l ExtUtils::AutoInstall" in the command line.
Your Makefile.PL should look like this:
# pull in ExtUtils/AutoInstall.pm from 'inc'
use lib 'inc';
use ExtUtils::AutoInstall (
-core => [ # mandatory modules
'Module0' => '', # any version would suffice
],
'Feature1' => [
# do we want to install this feature by default?
-default => ( system('feature1 --version') == 0 ),
Module1 => '0.01',
],
'Feature2' => [
# associate tests to be disabled if this feature is missing
-tests => [ <t/feature2*.t> ],
# associate tests to be disabled if this feature is present
-skiptests => [ <t/nofeature2*.t> ],
Module2 => '0.02',
],
'Feature3' => { # hash reference works, too
# force installation even if tests fail
Module2 => '0.03',
}
);
WriteMakefile(
AUTHOR => 'Joe Hacker <joe@hacker.org>',
ABSTRACT => 'Perl Interface to Joe Hacker',
NAME => 'Joe::Hacker',
VERSION_FROM => 'Hacker.pm',
DISTNAME => 'Joe-Hacker',
);
Self-Download Code
If you do not wish to put a copy of ExtUtils::AutoInstall under inc/, and are confident
that users will have internet access, you may replace the "use lib 'inc';" line with this
block of code:
# ExtUtils::AutoInstall Bootstrap Code, version 7.
BEGIN{my$p='ExtUtils::AutoInstall';my$v=0.45;$p->VERSION||0>=$v
or+eval"use $p $v;1"or+do{my$e=$ENV{PERL_EXTUTILS_AUTOINSTALL};
(!defined($e)||$e!~m/--(?:default|skip|testonly)/and-t STDIN or
eval"use ExtUtils::MakeMaker;WriteMakefile(PREREQ_PM=>{'$p',$v}
);1"and exit)and print"==> $p $v required. Install it from CP".
"AN? [Y/n] "and<STDIN>!~/^n/i and print"*** Installing $p\n"and
do{if (eval '$>' and lc(`sudo -V`) =~ /version/){system('sudo',
$^X,"-MCPANPLUS","-e","CPANPLUS::install $p");eval"use $p $v;1"
||system('sudo', $^X, "-MCPAN", "-e", "CPAN::install $p")}eval{
require CPANPLUS;CPANPLUS::install$p};eval"use $p $v;1"or eval{
require CPAN;CPAN::install$p};eval"use $p $v;1"||die"*** Please
manually install $p $v from cpan.org first...\n"}}}
If the user did not have ExtUtils::AutoInstall installed, the block of code above will
automatically download and install it.
However, due to its space-compressed (and obfuscated) nature, you should think twice
before employing this block of code; it is usually much more desirable to just use
Module::Install instead.
SEE ALSO
perlmodlib, ExtUtils::MakeMaker, Sort::Versions, CPAN, CPANPLUS, Module::Install
ACKNOWLEDGEMENTS
The test script included in the ExtUtils::AutoInstall distribution contains code adapted
from Michael Schwern's Test::More under the Perl License. Please consult to
t/AutoInstall.t for details.
See the AUTHORS file in this module's source distribution for the list of contributors.
AUTHORS
Autrijus Tang <autrijus@autrijus.org>
COPYRIGHT
Copyright 2001, 2002, 2003, 2004, 2005, 2016 by Autrijus Tang <autrijus@autrijus.org>.
This program is free software; you can redistribute it and/or modify it under the same
terms as Perl itself.
See <http://www.perl.com/perl/misc/Artistic.html>