Awesome

TITLE

Inline::Perl5

SYNOPSIS

    use DBI:from<Perl5>;

    my $dbh = DBI.connect('dbi:Pg:database=test');
    my $products = $dbh.selectall_arrayref(
    	'select * from products', {Slice => {}}
    );

DESCRIPTION

Module for executing Perl 5 code and accessing Perl 5 modules from Raku.

Supports Perl 5 modules including XS modules. Allows passing integers, strings, arrays, hashes, code references, file handles and objects between Perl 5 and Raku. Also supports calling methods on Perl 5 objects from Raku and calling methods on Raku objects from Perl 5 and subclass Perl 5 classes in Raku.

Note that installing Inline::Perl5 requires the Perl 5 library to be installed. See the BUILDING section for more information.

HOW DO I?

Load a Perl 5 module

Raku's use statement allows you to load modules from other languages as well. Inline::Perl5 registers as a handler for the Perl5 language. Rakudo will automatically load Inline::Perl5 as long as it is installed:

    use Test::More:from<Perl5>;

In Raku the :ver adverb is used for requiring a minimum version of a loaded module:

    use Test::More:from<Perl5>:ver<1.001014>;

Inline::Perl5's use() method maps to Perl 5's use statement:

    use Inline::Perl5;
    my $p5 = Inline::Perl5.new;
    $p5.use('Test::More');

To load a Perl 5 module from a specific folder:

    use lib:from<Perl5> 'lib';
    use MyModule:from<Perl5>;

Load a Perl 5 module and import functions

Just list the functions or groups you want to import

    use Digest::SHA1:from<Perl5> <sha1_hex>;

    use Data::Random:from<Perl5> <:all>;

Call a Perl 5 function

Inline::Perl5 creates wrappers for loaded Perl 5 modules and their functions. They can be used as if they were Raku modules:

    use Test::More:from<Perl5>;
    plan tests => 1;
    ok 'yes', 'looks like a Raku function';

In this example, the plan function exported by Test::More is called.

Inline::Perl5's call($name, *@args) method allows calling arbitrary Perl 5 functions. Use a fully qualified name (like "Test::More::ok") if the function is not in the "main" namespace.

    use Inline::Perl5;
    my $p5 = Inline::Perl5.new;
    $p5.call('print', 'Hello World');
    $p5.use('Test::More');
    $p5.call('Test::More::plan', tests => 1);

Please note that since Raku does not have the same concept of "context", Perl 5 functions are by default called in list context. See "Invoking a method in scalar context" for how to get around that.

Create a Perl 5 object / call a Perl 5 package method

Creating Perl 5 objects works just the same as in Perl 5: invoke their constructor (usually called "new").

    use Inline::Perl5;
    use Data::Dumper:from<Perl5>;
    my $dumper = Data::Dumper.new;

Or using the low level methods:

    use Inline::Perl5;
    my $p5 = Inline::Perl5.new;
    $p5.use('Data::Dumper');
    my $dumper = $p5.invoke('Data::Dumper', 'new');

Please note that since Raku does not have the same concept of "context", Perl 5 methods are by default called in list context. See "Invoking a method in scalar context" for how to get around that.

Invoke a method on a Perl 5 object

Once you have a Perl 5 object in a variable it will behave just like a Raku object. You can call methods on it like on any other object.

    use IO::Compress::Bzip2:from<Perl5>;
    my $bzip2 = IO::Compress::Bzip2.new('/tmp/foo.bz2');
    $bzip2.print($data);
    $bzip2.close;

Invoking a method in scalar context

Please note that since Raku does not have the same concept of "context", Perl 5 methods are by default called in list context. If you need to call the method in scalar context, you can tell it so explicitly, by passing the Scalar type object as first argument:

    use IO::Compress::Bzip2:from<Perl5>;
    my $bzip2 = IO::Compress::Bzip2.new(Scalar, '/tmp/foo.bz2');
    $bzip2.print(Scalar, $data);
    $bzip2.close(Scalar);

This may be neccessary if the Perl 5 method exposes different behavior when called in list and scalar context. Calling in scalar context may also improve performance in some cases.

Access a Perl 5 object's data directly

Most objects in Perl 5 are blessed hash references. Some of them don't even provide accessor methods but require you to just access the hash fields directly. This works the same in Raku:

    use Foo:from<Perl5>;
    my $foo = Foo.new;
    say $foo<some_attribute>;

Run arbitrary Perl 5 code

Raku's EVAL function supports multiple languages, just like the "use" statement. It allows for execution of arbitrary Perl 5 code given as string:

    EVAL "print 'Hello from Perl 5';", :lang<Perl5>;

The low level interface to this functionality is Inline::Perl5's run($str) method:

    use Inline::Perl5;
    my $p5 = Inline::Perl5.new;

    $p5.run(q'
        sub test {
            return 'Hello from Perl 5';
        }
    ');

Both "EVAL" and "run" return the value of the last statement in the EVAL'ed code.

Call a Raku function from Perl 5

Inline::Perl5 creates a Perl 5 package called "v6". This package contains a "call" function which allows for calling Raku functions from Perl 5, same as Inline::Perl5's "call" method. It takes the name of the function to call and passes on any additional arguments and returns the return value of the called Perl 5 function.

    use Inline::Perl5;
    my $p5 = Inline::Perl5.new;

    our sub foo($str) {
        say "Raku says hello to $str";
    };

    $p5.run(q:to/PERL5/);
        v6::call("foo", "Perl 5");
    PERL5

Invoke a method on a Raku object from Perl 5

Raku objects passed to Perl 5 functions will behave just like any other objects in Perl 5, so you can invoke methods using the -> operator.

    use Inline::Perl5;
    my $p5 = Inline::Perl5.new;

    $p5.run(q'
        sub test {
            my ($raku) = @_;
            $raku->hello;
        }
    ');

    class Foo {
        method hello {
            say "Hello Raku";
        }
    }

    $p5.call('test', Foo.new);

Run arbitrary Raku code from Perl 5

The "run" function in the automatically created "v6" package can be used to execute arbitrary Raku code from Perl 5. It returns the value of the last evaluated expression in the executed code.

    use Inline::Perl5;
    my $p5 = Inline::Perl5.new;

    $p5.run(q:to/PERL5/);
        v6::run("say foo");
    PERL5

Inherit from a Perl 5 class

Inline::Perl5 creates a corresponding Raku class for each Perl 5 module loaded via the <code>use Foo:from<Perl5></code> or <code>$p5.use('Foo')</code> mechanisms.

You can subclass these automatically created classes as if they were original Raku classes:

    use Data::Dumper:from<Perl5>;
    class MyDumper is Data::Dumper {
        has $.bar;
        method foo { say "foo!"; }
    }
    my $dumper = MyDumper.new([1], bar => 1);
    say $dumper.Dump();
    say $dumper.foo;
    say $dumper.bar;

You can override methods and the overridden methods will be called even by the Perl 5 methods in your base class. However, it is not yet possible to directly write to the Perl 5 object's data, i.e. <code>$self->{foo} = 1;</code>. Read access however is possible, i.e. <code>my $foo = self<foo>;</code>.

When <code>use</code> cannot be used to load the Perl 5 module, the Inline::Perl5::Perl5Parent role allows can be used for subclassing. Pass the Perl 5 package's name as parameter to the role. Pass the Inline::Perl5 object as named parameter to your classes constructor when creating objects.

    $p5.run(q:heredoc/PERL5/);

    package Foo;

    sub test {
        my ($self) = @_;

        return $self->bar;
    }

    PERL5

    class Bar does Inline::Perl5::Perl5Parent['Foo'] {
        method bar {
            return "Raku";
        }
    }

    use Inline::Perl5;
    my $p5 = Inline::Perl5.new;
    say Bar.new(perl5 => $p5).test;

Pass a scalar reference to Perl 5 code

Simply pass a Capture object containing the object you want to pass as a reference:

    $p5obj.takes-a-scalar-ref-to-str: \("the string");

HASH and ARRAY references are made automatically if the Raku objects are containerized:

    $p5obj.takes-an-array:      [<a b c>];
    $p5obj.takes-an-array-ref: $[<a b c>];

CODE objects are passed by reference automatically:

    $p5obj.takes-a-coderef: *.so;

Regex objects are passed by reference automatically:

    $p5obj.takes-a-regex: /foo/;

Catch exceptions thrown by Perl 5 code

Perl 5's exceptions (die) are translated to X::AdHoc exceptions in Raku and can be caught like any other Raku exceptions:

    {
        EVAL "die 'a Perl 5 exception!';", :lang<Perl5>;
        CATCH {
            when X::AdHoc {
                say "Caught a Perl 5 exception: $_";
            }
        }
    }

Catch exceptions thrown by Raku code in Perl 5

Raku's exceptions (die) are translated to Perl 5 exceptions and can be caught like any other Perl 5 exceptions:

    EVAL q:to:PERL5, :lang<Perl5>;
        use 5.10.0;
        eval {
            v6::run('die("test");');
        };
        say $@;
    PERL5

Mix Perl 5 and Raku code in the same file

Inline::Perl5 creates a virtual module called "v6-inline". By saying "use v6-inline;" in a Perl 5 module, you can declare that the rest of the file is written in Raku:

    package Some::Perl5::Module;

    use v6-inline;

    has $.name;

    sub greet {
        say "Hello $.name";
    }

Note that this Perl 5 module obviously will only work when Inline::Perl5 is loaded, i.e. in a Raku program or if you are using Inline::Perl6 in Perl 5. This functionality is aimed at supporting Perl 5 frameworks (think Catalyst or DBIx::Class or Dancer or ...) that automatically load modules and of course expect these modules to be written in Perl 5.

BUILDING

The oldest rakudo version supported is 2019.03.1. The oldest perl version supported is 5.20.0.

You will need a perl 5 built with the -fPIC option (position independent code). Most distributions build their Perl 5 that way. When you use perlbrew, you have to build it as:

perlbrew install perl-stable -Duseshrplib

(or, if you want to use more than one Inline::Perl5 interpeter safely, for instance from within Raku threads, add the -Dusemultiplicity option as well)

If you use plenv:

plenv install 5.24.0 -Duseshrplib

If you use the perl that comes with a Linux distribution, you may need to install a separate package containing the perl library. Consult the table below or the distribution documentation for details.

Build Inline::Perl5 with

raku configure.pl6
make

and test with

make test

and install with

make install

AUTHOR

Stefan Seifert nine@detonation.org