Alien::Build::Manual::AlienUser - Alien user documentation


version 2.80


 perldoc Alien::Build::Manual::AlienUser


This document is intended for a user of an Alien::Base based Alien module's user. Although specifically geared for Alien::Base subclasses, it may have some useful hints for Alien in general.

Full working examples of how to use an Alien module are also bundled with Alien::Build in the distribution's example/user directory. Those examples use Alien::xz, which uses alienfile + Alien::Build + Alien::Base.

The following documentation will assume you are trying to use an Alien called Alien::Foo which provides the library libfoo and the command line tool foo. Many Aliens will only provide one or the other.

The best interface to use for using Alien::Base based aliens is Alien::Base::Wrapper. This allows you to combine multiple aliens together and handles a number of corner obscure corner cases that using Aliens directly does not. Also as of 0.64, Alien::Base::Wrapper comes bundled with Alien::Build and Alien::Base anyway, so it is not an extra dependency.

What follows are the main use cases.


 use ExtUtils::MakeMaker;
 use Alien::Base::Wrapper ();
     NAME => 'FOO::XS',

Alien::Base::Wrapper will take a hash of WriteMakefile arguments and insert the appropriate compiler and linker flags for you. This is recommended over doing this yourself as the exact incantation to get EUMM to work is tricky to get right.

The mm_args2 method will also set your CONFIGURE_REQUIRES for Alien::Base::Wrapper, ExtUtils::MakeMaker and any aliens that you specify.


 use Module::Build;
 use Alien::Base::Wrapper qw( Alien::Foo !export );
 use Alien::Foo;
 my $build = Module::Build->new(
   configure_requires => {
     'Alien::Base::Wrapper' => '0',
     'Alien::Foo'           => '0',

For Module::Build you can also use Alien::Base::Wrapper, but you will have to specify the configure_requires yourself.

Inline::C / Inline::CPP

 use Inline 0.56 with => 'Alien::Foo';

Inline::C and Inline::CPP can be configured to use an Alien::Base based Alien with the with keyword.


 use ExtUtils::MakeMaker;
 use ExtUtils::Depends;
 my $pkg = ExtUtils::Depends->new("Alien::Foo");

ExtUtils::Depends works similar to Alien::Base::Wrapper, but uses the Inline interface under the covers.


 -bundle = @Basic
 -remove = MakeMaker
 [Prereqs / ConfigureRequires]
 Alien::Foo = 0
 header = use Alien::Base::Wrapper qw( Alien::Foo !export );
 WriteMakefile_arg = Alien::Base::Wrapper->mm_args


Requires Alien::Foo always:

 use FFI::Platypus;
 use Alien::Foo;
 my $ffi = FFI::Platypus->new(
   lib => [ Alien::Foo->dynamic_libs ],

Use Alien::Foo in fallback mode:

 use FFI::Platypus;
 use FFI::CheckLib 0.28 qw( find_lib_or_die );
 use Alien::Foo;
 my $ffi = FFI::Platypus->new(
   lib => [ find_lib_or_die lib => 'foo', alien => ['Alien::Foo'] ],

If you are going to always require an Alien you can just call dynamic_libs and pass it into FFI::Platypus' lib method. You should consider using FFI::CheckLib to use the Alien in fallback mode instead. This way you only need to install the Alien if the system doesn't provide it.

For fallback mode to work correctly you need to be using FFI::CheckLib 0.28 or better.


 use Inline with => 'Alien::Foo';
 use Inline C => <<~'END';
   #include <foo.h>
   const char *my_foo_wrapper()
 sub exported_foo()


 use Alien::Foo;
 use Env qw( @PATH );
 unshift @PATH, Alien::Foo->bin_dir;
 system 'foo', '--bar', '--baz';

Some Aliens provide tools instead of or in addition to a library. You need to add them to the PATH environment variable though. (Unless the tool is already provided by the system, in which case it is already in the path and the bin_dir method will return an empty list).



Although the recommended way for a consumer to use an Alien::Base based Alien is to declare it as a static configure and build-time dependency, some consumers may prefer to fallback on using an Alien only when the consumer itself cannot detect the necessary package. In some cases the consumer may want the user to opt-in to using an Alien before requiring it.

To keep the interface consistent among Aliens, the consumer of the fallback opt-in Alien may fallback on the Alien if the environment variable ALIEN_INSTALL_TYPE is set to any value. The rationale is that by setting this environment variable the user is aware that Alien modules may be installed and have indicated consent. The actual implementation of this, by its nature would have to be in the consuming CPAN module.

This behavior should be documented in the consumer's POD.

See "ENVIRONMENT" in Alien::Build for more details on the usage of this environment variable.



Other Alien::Build manuals.


Author: Graham Ollis <>


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This software is copyright (c) 2011-2022 by Graham Ollis.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.