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Alien-Build-0.47
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/ Alien::Build::Manual::PluginAuthor

NAME

Alien::Build::Manual::PluginAuthor - Alien::Build plugin author documentation

VERSION

version 0.47

SYNOPSIS

perldoc Alien::Build::Manual::PluginAuthor

DESCRIPTION

This document explains how to write Alien::Build plugins using the Alien::Build::Plugin base class.

TODO

HOOKS

probe hook

$meta->register_hook( probe => sub {
  my($build) = @_;
  return 'system' if ...; # system install
  return 'share';         # otherwise
});

$meta->register_hook( probe => [ $command ] );

This hook should return the string system if the operating system provides the library or tool. It should return share otherwise.

You can also use a command that returns true when the tool or library is available. For example for use with pkg-config:

$meta->register_hook( probe =>
  [ '%{pkgconf} --exists libfoo' ] );

Or if you needed a minimum version:

$meta->register_hook( probe =>
  [ '%{pkgconf} --atleast-version=1.00 libfoo' ] );

Note that this hook SHOULD NOT gather system properties, such as cflags, libs, versions, etc, because the probe hook will be skipped in the even the environment variable ALIEN_INSTALL_TYPE is set. The detection of these properties should instead be done by the gather_system hook, below.

gather_system hook

$meta->register_hook( gather_system => sub {
  my($build) = @_;
  $build->runtime_prop->{cflags}  = ...;
  $build->runtime_prop->{libs}    = ...;
  $build->runtime_prop->{version} = ...;
});

This hook is called for a system install to determine the properties necessary for using the library or tool. These properties should be stored in the runtime_prop hash as shown above. Typical properties that are needed for libraries are cflags and libs. If at all possible you should also try to determine the version of the library or tool.

download hook

$meta->register_hook( download => sub {
  my($build) = @_;
  ...
});

This hook is used to download from the internet the source. Either as an archive (like tar, zip, etc), or as a directory of files (git clone, etc). When the hook is called, the current working directory will be a new empty directory, so you can save the download to the current directory. If you store a single file in the directory, Alien::Build will assume that it is an archive, which will be processed by the extract hook below. If you store multiple files, Alien::Build will assume the current directory is the source root. If no files are stored at all, an exception with an appropriate diagnostic will be thrown.

Note: If you register this hook, then the fetch, decode and prefer hooks will NOT be called.

fetch hook

package Alien::Build::Plugin::MyPlugin;

use strict;
use warnings;
use Alien::Build::Plugin;
use Carp ();

has '+url' => sub { Carp::croak "url is required property" };

sub init
{
  my($self, $meta) = @_;
  
  $meta->register_hook( fetch => sub {
    my($build, $url) = @_;
    ...
  }
}

1;

Used to fetch a resource. The first time it will be called without an argument, so the configuration used to find the resource should be specified by the plugin's properties. On subsequent calls the first argument will be a URL.

Normally the first fetch will be to either a file or a directory listing. If it is a file then the content should be returned as a hash reference with the following keys:

# content of file stored in Perl
return {
  type     => 'file',
  filename => $filename,
  content  => $content,
  version  => $version,  # optional, if known
};

# content of file stored in the filesystem
return {
  type     => 'file',
  filename => $filename,
  path     => $path,    # full file system path to file
  version  => $version,  # optional, if known
};

If the URL points to a directory listing you should return it as either a hash reference containing a list of files:

return {
  type => 'list',
  list => [
    # filename: each filename should be just the
    #   filename portion, no path or url.
    # url: each url should be the complete url
    #   needed to fetch the file.
    { filename => $filename1, url => $url1 },
    { filename => $filename2, url => $url2 },
  ]
};

or if the listing is in HTML format as a hash reference containing the HTML information:

return {
  type => 'html',
  charset => $charset, # optional
  base    => $base,    # the base URL: used for computing relative URLs
  content => $content, # the HTML content
};

or a directory listing (usually produced by ftp servers) as a hash reference:

return {
  type    => 'dir_listing',
  base    => $base,
  content => $content,
};

decode hook

sub init
{
  my($self, $meta) = @_;
  
  $meta->register_hook( decode => sub {
    my($build, $res) = @_;
    ...
  }
}

This hook takes a response hash reference from the fetch hook above with a type of html or dir_listing and converts it into a response hash reference of type list. In short it takes an HTML or FTP file listing response from a fetch hook and converts it into a list of filenames and links that can be used by the prefer hook to choose the correct file to download. See fetch for the specification of the input and response hash references.

prefer hook

sub init
{
  my($self, $meta) = @_;
  
  $meta->register_hook( prefer => sub {
    my($build, $res) = @_;
    return {
      type => 'list',
      list => [sort @{ $res->{list} }],
    };
  }
}

This hook sorts candidates from a listing generated from either the fetch or decode hooks. It should return a new list hash reference with the candidates sorted from best to worst. It may also remove candidates that are totally unacceptable.

extract hook

$meta->register_hook( extract => sub {
  my($build, $archive) = @_;
  ...
});

patch hook

$meta->register_hook( patch => sub {
  my($build) = @_;
  ...
});

This hook is completely optional. If registered, it will be triggered after extraction and before build. It allows you to apply any patches or make any modifications to the source if they are necessary.

patch_ffi hook

$meta->register_hook( patch_ffi => sub {
  my($build) = @_;
  ...
});

build hook

$meta->register_hook( build => sub {
  my($build) = @_;
  ...
});

build_ffi hook

$meta->register_hook( build_ffi => sub {
  my($build) = @_;
  ...
});

gather_share hook

$meta->register_hook( register_hook => sub {
  my($build) = @_;
  ... 
});

gather_ffi hook

$meta->register_hook( register_ffi => sub {
  my($build) = @_;
  ... 
});

AUTHOR

Author: Graham Ollis <plicease@cpan.org>

Contributors:

Diab Jerius (DJERIUS)

Roy Storey

COPYRIGHT AND LICENSE

This software is copyright (c) 2017 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.