Implement dynamic prerequisites

dist.ini

@@ -20,8 +20,10 @@ skip = Foo::Bar
 [Git::NextVersion]
 [MetaProvides::Package]
 
-[BuildSelf]
-auto_configure_requires = 1
+[ModuleBuildTiny]
+auto_configure_requires = 0
+header = use lib 'lib';
+[ConfigureSelf]
 
 [PodSyntaxTests]
 
@@ -57,3 +59,4 @@ check_dual_life_versions = 0
 skip = ExtUtils::Config
 skip = ExtUtils::Helpers
 skip = ExtUtils::InstallPaths
+skip = CPAN::Requirements::Dynamic

lib/Module/Build/Tiny.pm

@@ -161,15 +161,23 @@ my %actions = (
 	},
 );
 
+sub get_arguments {
+	my @sources = @_;
+	my %opt;
+	GetOptionsFromArray($_, \%opt, qw/install_base=s install_path=s% installdirs=s destdir=s prefix=s config=s% uninst:1 verbose:1 dry_run:1 pureperl-only:1 create_packlist=i jobs=i/) for (@sources);
+	$_ = detildefy($_) for grep { defined } @opt{qw/install_base destdir prefix/}, values %{ $opt{install_path} };
+	$opt{config} = ExtUtils::Config->new($opt{config});
+	$opt{meta} = get_meta();
+	$opt{install_paths} = ExtUtils::InstallPaths->new(%opt, dist_name => $opt{meta}->name);
+	return %opt;
+}
+
 sub Build {
 	my $action = @ARGV && $ARGV[0] =~ /\A\w+\z/ ? shift @ARGV : 'build';
 	die "No such action '$action'\n" if not $actions{$action};
 	my($env, $bargv) = @{ decode_json(read_file('_build_params')) };
-	my %opt;
-	GetOptionsFromArray($_, \%opt, qw/install_base=s install_path=s% installdirs=s destdir=s prefix=s config=s% uninst:1 verbose:1 dry_run:1 pureperl-only:1 create_packlist=i jobs=i/) for ($env, $bargv, \@ARGV);
-	$_ = detildefy($_) for grep { defined } @opt{qw/install_base destdir prefix/}, values %{ $opt{install_path} };
-	@opt{ 'config', 'meta' } = (ExtUtils::Config->new($opt{config}), get_meta());
-	exit $actions{$action}->(%opt, install_paths => ExtUtils::InstallPaths->new(%opt, dist_name => $opt{meta}->name));
+	my %opt = get_arguments($env, $bargv, \@ARGV);
+	exit $actions{$action}->(%opt);
 }
 
 sub Build_PL {
@@ -180,6 +188,15 @@ sub Build_PL {
 	make_executable('Build');
 	my @env = defined $ENV{PERL_MB_OPT} ? split_like_shell($ENV{PERL_MB_OPT}) : ();
 	write_file('_build_params', encode_json([ \@env, \@ARGV ]));
+	if (my $dynamic = $meta->custom('x_dynamic_prereqs')) {
+		my %meta = (%{ $meta->as_struct }, dynamic_config => 0);
+		my %opt = get_arguments(\@env, \@ARGV);
+		require CPAN::Requirements::Dynamic;
+		my $dynamic_parser = CPAN::Requirements::Dynamic->new(%opt);
+		my $prereq = $dynamic_parser->evaluate($dynamic);
+		$meta{prereqs} = $meta->effective_prereqs->with_merged_prereqs($prereq)->as_string_hash;
+		$meta = CPAN::Meta->new(\%meta);
+	}
 	$meta->save(@$_) for ['MYMETA.json'], [ 'MYMETA.yml' => { version => 1.4 } ];
 }
 
@@ -220,14 +237,14 @@ than 200, yet supports the features needed by most distributions.
 
 =item * Module sharedirs
 
+=item * Dynamic prerequisites
+
 =back
 
 =head2 Not Supported
 
 =over 4
 
-=item * Dynamic prerequisites
-
 =item * HTML documentation generation
 
 =item * Extending Module::Build::Tiny

t/lib/DistGen.pm

@@ -153,23 +153,39 @@ sub _gen_default_filedata {
     ok 1;
     ---
 
-  $self->$add_unless('META.yml', undent(<<"    ----"));
-    ---
-    name: $dist_name
-    version: 0.001
-    author:
-      - 'David Golden <dagolden\@cpan.org>'
-      - 'Leon Timmermans <leont\@cpan.org>'
-    abstract: 'A testing dist'
-    license: perl
-    requires:
-      perl: 5.006
-      Module::Build::Tiny: 0
-    generated_by: Leon Timmermans
-    dynamic_config: 0
-    meta-spec:
-      url: http://module-build.sourceforge.net/META-spec-v1.4.html
-      version: 1.4
+  $self->$add_unless('META.json', undent(<<"    ----"));
+	{
+		"name": "Foo-Bar",
+		"version": 0.001,
+		"author": [
+			"David Golden <dagolden\@cpan.org>",
+			"Leon Timmermans <leont\@cpan.org>"
+		],
+		"abstract": "A testing dist",
+		"license": "perl_5",
+		"prereqs": {
+			"configure": {
+				"requires": {
+					"Module::Build::Tiny": 0
+				}
+			},
+			"runtime": {
+				"requires": {
+					"perl": 5.006
+				}
+			}
+		},
+		"generated_by": "Leon Timmermans",
+		"dynamic_config": 1,
+		"meta-spec": {
+			"url": "http://search.cpan.org/perldoc?CPAN::Meta::Spec",
+			"version": 2
+		},
+        "x_dynamic_prereqs": {
+			"version": 1,
+			"expressions": [ { "condition": [ "has_perl", "$]"], "prereqs": { "Bar": 1 } } ]
+        }
+	  }
     ----
 }
 

t/simple.t

@@ -136,6 +136,13 @@ sub _slurp { do { local (@ARGV,$/)=$_[0]; <> } }
   ok( -d catdir(qw/blib lib auto share module Foo-Bar/), 'moduole sharedir has been made');
   ok( -f catfile(qw/blib lib auto share module Foo-Bar file.txt/), 'module sharedir file has been made');
 
+  require CPAN::Meta;
+  my $meta = CPAN::Meta->load_file("MYMETA.json");
+  my $req = $meta->effective_prereqs->requirements_for('runtime', 'requires');
+  my $dynamic_dependency = join ',', sort $req->required_modules;
+
+  is($dynamic_dependency, 'Bar,perl', 'Dependency on Foo has been inserted');
+
   if ($has_compiler) {
     XSLoader::load('Foo::Bar');
     is(Foo::Bar::foo(), "Hello World!\n", 'Can run XSub Foo::Bar::foo');