Inline-API - How to bind a programming language to Perl using Inline.pm |
register()
Callbackvalidate()
Callbackbuild()
Callbackload()
Callbackinfo()
Callback
Inline-API - How to bind a programming language to Perl using Inline.pm
#!/usr/bin/perl
use Inline Foo; say_it('foo'); # Use Foo to print "Hello, Foo"
__Foo__ foo-sub say_it { foo-my $foo = foo-shift; foo-print "Hello, $foo\n"; }
So you think Inline C is pretty cool, but what you really need is for Perl to
work with the brand new programming language ``Foo''. Well you're in luck.
Inline.pm
has support for adding your own Inline Language Support Module
(ILSM), like Inline::Foo
.
Inline has always been intended to work with lots of different programming
languages. Many of the details can be shared between implementations, so that
Inline::Java
has a similar interface to Inline::ASM
. All of the common
code is in Inline.pm
.
Language specific modules like Inline::Python
are subclasses of
Inline.pm
. They can inherit as much of the common behaviour as they want,
and provide specific behaviour of their own. This usually comes in the form of
Configuration Options and language specific compilation.
The Inline C support is probably the best boilerplate to copy from. Since
version 0.30 all C support was isolated into the module Inline::C
and the
parsing grammar is further broken out into Inline::C::grammar
. All of these
components come with the Inline distribution.
This POD gives you all the details you need for implementing an ILSM. For further assistance, contact inline@perl.org See [``SEE ALSO''] below.
We'll examine the joke language Inline::Foo which is distributed with Inline. It actually is a full functioning ILSM. I use it in Inline's test harness to test base Inline functionality. It is very short, and can help you get your head wrapped around the Inline API.
For the remainder of this tutorial, let's assume we're writing an ILSM for the
ficticious language Foo
. We'll call it Inline::Foo
. Here is the entire
(working) implementation.
package Inline::Foo; use strict; $Inline::Foo::VERSION = '0.01'; @Inline::Foo::ISA = qw(Inline); require Inline; use Carp;
#=========================================================== # Register Foo as an Inline Language Support Module (ILSM) #=========================================================== sub register { return { language => 'Foo', aliases => ['foo'], type => 'interpreted', suffix => 'foo', }; }
#=========================================================== # Error messages #=========================================================== sub usage_config { my ($key) = @_; "'$key' is not a valid config option for Inline::Foo\n"; }
sub usage_config_bar { "Invalid value for Inline::Foo config option BAR"; }
#=========================================================== # Validate the Foo Config Options #=========================================================== sub validate { my $o = shift; $o->{ILSM}{PATTERN} ||= 'foo-'; $o->{ILSM}{BAR} ||= 0; while (@_) { my ($key, $value) = splice @_, 0, 2; if ($key eq 'PATTERN') { $o->{ILSM}{PATTERN} = $value; next; } if ($key eq 'BAR') { croak usage_config_bar unless $value =~ /^[01]$/; $o->{ILSM}{BAR} = $value; next; } croak usage_config($key); } }
#=========================================================== # Parse and compile Foo code #=========================================================== sub build { my $o = shift; my $code = $o->{API}{code}; my $pattern = $o->{ILSM}{PATTERN}; $code =~ s/$pattern//g; $code =~ s/bar-//g if $o->{ILSM}{BAR}; sleep 1; # imitate compile delay { package Foo::Tester; eval $code; } croak "Foo build failed:\n$@" if $@; my $path = "$o->{API}{install_lib}/auto/$o->{API}{modpname}"; my $obj = $o->{API}{location}; $o->mkpath($path) unless -d $path; open FOO_OBJ, "> $obj" or croak "Can't open $obj for output\n$!"; print FOO_OBJ $code; close \*FOO_OBJ; }
#=========================================================== # Only needed for interpreted languages #=========================================================== sub load { my $o = shift; my $obj = $o->{API}{location}; open FOO_OBJ, "< $obj" or croak "Can't open $obj for output\n$!"; my $code = join '', <FOO_OBJ>; close \*FOO_OBJ; eval "package $o->{API}{pkg};\n$code"; croak "Unable to load Foo module $obj:\n$@" if $@; }
#=========================================================== # Return a small report about the Foo code. #=========================================================== sub info { my $o = shift; my $text = <<'END'; This is a small report about the Foo code. Perhaps it contains information about the functions the parser found which will be bound to Perl. It will get included in the text produced by the Inline 'INFO' command. END return $text; }
1;
Except for load()
, the subroutines in this code are mandatory for an ILSM.
What they do is described below. A few things to note:
@Inline::Foo::ISA = qw(Inline);
require Inline;
' is not necessary. But it is there to remind you not to say 'use Inline;
'. This will not work.use Inline::Foo;
Inline.pm
will detect such usage for you in its import
method, which is
automatically inherited since Inline::Foo
is a subclass.
This section is a more formal specification of what functionality you'll need to provide to implement an ILSM.
When Inline determines that some Foo
code needs to be compiled it will
automatically load your ILSM module. It will then call various subroutines
which you need to supply. We'll call these subroutines ``callbacks''.
You will need to provide the following 5 callback subroutines.
register()
CallbackThis subroutine receives no arguments. It returns a reference to a hash of ILSM meta-data. Inline calls this routine only when it is trying to detect new ILSM-s that have been installed on a given system. Here is an example of the has ref you would return for Foo:
{ language => 'Foo', aliases => ['foo'], type => 'interpreted', suffix => 'foo', };
The meta-data items have the following meanings:
Inline::X
for a given language 'X'.
Config.pm
.
For interpreted languages, this value can be whatever you want. Python uses
pydat
. Foo uses foo
.
validate()
CallbackThis routine gets passed all configuration options that were not already handled by the base Inline module. The options are passed as key/value pairs. It is up to you to validate each option and store its value in the Inline object (which is also passed in). If a particular option is invalid, you should croak with an appropriate error message.
Note that all the keywords this routine receives will be converted to upper-
case by Inline
, whatever case the program gave.
build()
CallbackThis subroutine is responsible for doing the parsing and compilation of the
Foo source code. The Inline object is passed as the only argument. All
pertinent information will be stored in this object. build()
is required to
create a cache object of a specific name, or to croak with an appropriate
error message.
This is the meat of your ILSM. Since it will most likely be quite complicated,
it is probably best that you study an existing ILSM like Inline::C
.
load()
CallbackThis method only needs to be provided for interpreted languages. It's responsibility is to start the interpreter.
For compiled languages, the load routine from Inline.pm
is called which
uses DynaLoader
to load the shared object or DLL.
info()
CallbackThis method is called when the user makes use of the INFO
shortcut. You
should return a string containing a small report about the Inlined code.
Inline.pm
creates a hash based Perl object for each section of Inlined
source code it receives. This object contains lots of information about the
code, the environment, and the configuration options used.
This object is a hash that is broken into several subhashes. The only two subhashes that an ILSM should use at all are $o->{API} and $o->{ILSM}. The first one contains all of the information that Inline has gather for you in order for you to create/load a cached object of your design. The second one is a repository where your ILSM can freely store data that it might need later on.
This section will describe all of the Inline object ``API'' attributes.
Inline.pm
being used.
Inline.pm
has been set up so that anyone can write their own language
support modules. It further allows anyone to write a different implementation
of an existing Inline language, like C for instance. You can distribute that
module on the CPAN.
If you have plans to implement and distribute an Inline module, I would ask that you please work with the Inline community. We can be reached at the Inline mailing list: inline@perl.org (Send mail to inline-subscribe@perl.org to subscribe). Here you should find the advice and assistance needed to make your module a success.
The Inline community will decide if your implementation of COBOL will be
distributed as the official Inline::COBOL
or should use an alternate
namespace. In matters of dispute, I (Ingy döt Net) retain final authority.
(and I hope not to need use of it :-) Actually modules@perl.org retains the
final authority.
But even if you want to work alone, you are free and welcome to write and distribute Inline language support modules on CPAN. You'll just need to distribute them under a different package name.
For generic information about Inline, see Inline.
For information about using Inline with C see the Inline::C manpage.
For information on supported languages and platforms see Inline-Support.
Inline's mailing list is inline@perl.org
To subscribe, send email to inline-subscribe@perl.org
Ingy döt Net <ingy@cpan.org>
Copyright 2000-2015. Ingy döt Net.
Copyright 2008, 2010, 2011. Sisyphus.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
See http://www.perl.com/perl/misc/Artistic.html
Inline-API - How to bind a programming language to Perl using Inline.pm |