# TITLE
Inline::Perl5
[](
https://travis-ci.org/niner/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 Perl 6.
Supports Perl 5 modules including XS modules. Allows passing integers,
strings, arrays, hashes, code references, file handles and objects between
Perl 5 and Perl 6. Also supports calling methods on Perl 5 objects from
Perl 6 and calling methods on Perl 6 objects from Perl 5 and subclass
Perl 5 classes in Perl 6.
# HOW DO I?
## Load a Perl 5 module
Perl 6' 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 Perl 6 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;
$p5.use('Test::More');
```
To load a Perl 5 module from a specific folder:
```
use lib:from<Perl5> 'lib';
use MyModule:from<Perl5>;
```
## Load a Perl 5 module and import functions
Just list the functions or groups you want to import
```
use Digest::SHA1:from<Perl5> <sha1_hex>;
```
```
use Data::Random:from<Perl5> <:all>;
```
## Call a Perl 5 function
Inline::Perl5 creates wrappers for loaded Perl 5 modules and their functions.
They can be used as if they were Perl 6 modules:
```
use Test::More:from<Perl5>;
plan tests => 1;
ok 'yes', 'looks like a Perl 6 function';
```
In this example, the `plan` function exported by `Test::More` is called.
Inline::Perl5's call($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 Perl 6 does not have the same concept of "context",
Perl 5 functions are always called in list context.
## 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 Perl 6 does not have the same concept of "context",
Perl 5 methods are always called in list context.
## Invoke a method on a Perl 5 object
Once you have a Perl 5 object in a variable it will behave just like a Perl 6
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 Perl 6 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 Perl 6:
```
use Foo:from<Perl5>;
my $foo = Foo.new;
say $foo<some_attribute>;
```
## Run arbitrary Perl 5 code
Perl6's EVAL function supports multiple languages, just like the "use"
statement. It allows for execution of arbitrary Perl 5 code given as string:
```
EVAL "print 'Hello from Perl 5';", :lang<Perl5>;
```
The low level interface to this functionality is Inline::Perl5's run($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 Perl 6 function from Perl 5
Inline::Perl5 creates a Perl 5 package called "v6". This package contains
a "call" function which allows for calling Perl 6 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 "Perl6 says hello to $str";
};
$p5.run(q:to/PERL5/);
v6::call("foo", "Perl 5");
PERL5
```
## Invoke a method on a Perl 6 object from Perl 5
Perl 6 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;
$p5.run(q'
sub test {
my ($perl6) = @_;
$perl6->hello;
}
');
class Foo {
method hello {
say "Hello Perl 6";
}
}
$p5.call('test', Foo.new);
```
## Run arbitrary Perl 6 code from Perl 5
The "run" function in the automatically created "v6" package can be used to
execute arbitrary Perl 6 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;
$p5.run(q:to/PERL5/);
v6::run("say foo");
PERL5
```
## Inherit from a Perl 5 class
Inline::Perl5 creates a corresponding Perl 6 class for each Perl 5 module
loaded via the <code>use Foo:from<Perl5></code> or <code>$p5.use('Foo')</code>
mechanisms.
You can subclass these automatically created classes as if they were original
Perl 6 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 "Perl6";
}
}
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`](
https://docs.perl6.org/type/Capture) object containing
the object you want to pass as a reference:
```perl6
$p5obj.takes-a-scalar-ref-to-str: \("the string");
```
`HASH` and `ARRAY` references are made automatically if the Perl 6 objects
are [containerized](
https://perl6advent.wordpress.com/2017/12/02/):
```perl6
$p5obj.takes-an-array: [<a b c>];
$p5obj.takes-an-array-ref: $[<a b c>];
```
`CODE` objects are passed by reference automatically:
```perl6
$p5obj.takes-a-coderef: *.so;
```
`Regex` objects are passed by reference automatically:
```perl6
$p5obj.takes-a-regex: /foo/;
```
## Catch exceptions thrown by Perl 5 code
Perl 5's exceptions (die) are translated to X::AdHoc exceptions in Perl 6 and
can be caught like any other Perl 6 exceptions:
```
{
EVAL "die 'a Perl 5 exception!';", :lang<Perl5>;
CATCH {
when X::AdHoc {
say "Caught a Perl 5 exception: $_";
}
}
}
```
## Catch exceptions thrown by Perl 6 code in Perl 5
Perl 6'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 Perl 6 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 Perl 6:
```
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 Perl 6 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
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 Perl 6 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. E.g. on Debian
this is called libperl-dev, on Fedora perl-libs. On openSUSE, the perl
package already contains everything needed.
Build Inline::Perl5 with
perl6 configure.pl6
make
and test with
make test
and install with
make install
# AUTHOR
Stefan Seifert <
[email protected]>
