1Inline-API(3)         User Contributed Perl Documentation        Inline-API(3)
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3
4

NAME

6       Inline-API - How to bind a programming language to Perl using Inline.pm
7

SYNOPSIS

9           #!/usr/bin/perl
10
11           use Inline Foo;
12           say_it('foo');  # Use Foo to print "Hello, Foo"
13
14           __Foo__
15           foo-sub say_it {
16               foo-my $foo = foo-shift;
17               foo-print "Hello, $foo\n";
18           }
19

DESCRIPTION

21       So you think Inline C is pretty cool, but what you really need is for
22       Perl to work with the brand new programming language "Foo". Well you're
23       in luck. "Inline.pm" has support for adding your own Inline Language
24       Support Module (ILSM), like "Inline::Foo".
25
26       Inline has always been intended to work with lots of different
27       programming languages. Many of the details can be shared between
28       implementations, so that "Inline::Java" has a similar interface to
29       "Inline::ASM". All of the common code is in "Inline.pm".
30
31       Language specific modules like "Inline::Python" are subclasses of
32       "Inline.pm". They can inherit as much of the common behaviour as they
33       want, and provide specific behaviour of their own. This usually comes
34       in the form of Configuration Options and language specific compilation.
35
36       The Inline C support is probably the best boilerplate to copy from.
37       Since version 0.30 all C support was isolated into the module
38       "Inline::C" and the parsing grammar is further broken out into
39       "Inline::C::grammar". All of these components come with the Inline
40       distribution.
41
42       This POD gives you all the details you need for implementing an ILSM.
43       For further assistance, contact inline@perl.org See "SEE ALSO" below.
44
45       We'll examine the joke language Inline::Foo which is distributed with
46       Inline. It actually is a full functioning ILSM. I use it in Inline's
47       test harness to test base Inline functionality. It is very short, and
48       can help you get your head wrapped around the Inline API.
49

A Skeleton

51       For the remainder of this tutorial, let's assume we're writing an ILSM
52       for the ficticious language "Foo". We'll call it "Inline::Foo". Here is
53       the entire (working) implementation.
54
55           package Inline::Foo;
56           use strict;
57           $Inline::Foo::VERSION = '0.01';
58           @Inline::Foo::ISA = qw(Inline);
59           require Inline;
60           use Carp;
61
62           #===========================================================
63           # Register Foo as an Inline Language Support Module (ILSM)
64           #===========================================================
65           sub register {
66               return {
67                   language => 'Foo',
68                   aliases => ['foo'],
69                   type => 'interpreted',
70                   suffix => 'foo',
71                  };
72           }
73
74           #===========================================================
75           # Error messages
76           #===========================================================
77           sub usage_config {
78               my ($key) = @_;
79               "'$key' is not a valid config option for Inline::Foo\n";
80           }
81
82           sub usage_config_bar {
83               "Invalid value for Inline::Foo config option BAR";
84           }
85
86           #===========================================================
87           # Validate the Foo Config Options
88           #===========================================================
89           sub validate {
90               my $o = shift;
91               $o->{ILSM}{PATTERN} ||= 'foo-';
92               $o->{ILSM}{BAR} ||= 0;
93               while (@_) {
94               my ($key, $value) = splice @_, 0, 2;
95               if ($key eq 'PATTERN') {
96                   $o->{ILSM}{PATTERN} = $value;
97                   next;
98               }
99               if ($key eq 'BAR') {
100                   croak usage_config_bar
101                     unless $value =~ /^[01]$/;
102                   $o->{ILSM}{BAR} = $value;
103                   next;
104               }
105               croak usage_config($key);
106               }
107           }
108
109           #===========================================================
110           # Parse and compile Foo code
111           #===========================================================
112           sub build {
113               my $o = shift;
114               my $code = $o->{API}{code};
115               my $pattern = $o->{ILSM}{PATTERN};
116               $code =~ s/$pattern//g;
117               $code =~ s/bar-//g if $o->{ILSM}{BAR};
118               sleep 1;             # imitate compile delay
119               {
120                   package Foo::Tester;
121                   eval $code;
122               }
123               croak "Foo build failed:\n$@" if $@;
124               my $path = "$o->{API}{install_lib}/auto/$o->{API}{modpname}";
125               my $obj = $o->{API}{location};
126               $o->mkpath($path) unless -d $path;
127               open FOO_OBJ, "> $obj"
128                 or croak "Can't open $obj for output\n$!";
129               print FOO_OBJ $code;
130               close \*FOO_OBJ;
131           }
132
133           #===========================================================
134           # Only needed for interpreted languages
135           #===========================================================
136           sub load {
137               my $o = shift;
138               my $obj = $o->{API}{location};
139               open FOO_OBJ, "< $obj"
140                 or croak "Can't open $obj for output\n$!";
141               my $code = join '', <FOO_OBJ>;
142               close \*FOO_OBJ;
143               eval "package $o->{API}{pkg};\n$code";
144               croak "Unable to load Foo module $obj:\n$@" if $@;
145           }
146
147           #===========================================================
148           # Return a small report about the Foo code.
149           #===========================================================
150           sub info {
151               my $o = shift;
152               my $text = <<'END';
153           This is a small report about the Foo code. Perhaps it contains
154           information about the functions the parser found which will be
155           bound to Perl. It will get included in the text produced by the
156           Inline 'INFO' command.
157           END
158               return $text;
159           }
160
161           1;
162
163       Except for "load()", the subroutines in this code are mandatory for an
164       ILSM. What they do is described below. A few things to note:
165
166       1.  "Inline::Foo" must be a subclass of Inline. This is accomplished
167           with:
168
169               @Inline::Foo::ISA = qw(Inline);
170
171       2.  The line '"require Inline;"' is not necessary. But it is there to
172           remind you not to say '"use Inline;"'. This will not work.
173
174       3.  Remember, it is not valid for a user to say:
175
176               use Inline::Foo;
177
178           "Inline.pm" will detect such usage for you in its "import" method,
179           which is automatically inherited since "Inline::Foo" is a subclass.
180
181       4.  In the build function, you normally need to parse your source code.
182           Inline::C uses Parse::RecDescent to do this. Inline::Foo simply
183           uses eval. (After we strip out all occurances of 'foo-').
184
185           An alternative parsing method that works well for many ILSMs (like
186           Java and Python) is to use the language's compiler itself to parse
187           for you.  This works as long as the compiler can be made to give
188           back parse information.
189

The Inline API

191       This section is a more formal specification of what functionality
192       you'll need to provide to implement an ILSM.
193
194       When Inline determines that some "Foo" code needs to be compiled it
195       will automatically load your ILSM module. It will then call various
196       subroutines which you need to supply. We'll call these subroutines
197       "callbacks".
198
199       You will need to provide the following 5 callback subroutines.
200
201   The register() Callback
202       This subroutine receives no arguments. It returns a reference to a hash
203       of ILSM meta-data. Inline calls this routine only when it is trying to
204       detect new ILSM-s that have been installed on a given system. Here is
205       an example of the has ref you would return for Foo:
206
207           {
208            language => 'Foo',
209            aliases => ['foo'],
210            type => 'interpreted',
211            suffix => 'foo',
212           };
213
214       The meta-data items have the following meanings:
215
216       language
217           This is the proper name of the language. It is usually implemented
218           as "Inline::X" for a given language 'X'.
219
220       aliases
221           This is a reference to an array of language name aliases. The
222           proper name of a language can only contain word characters.
223           [A-Za-z0-9_] An alias can contain any characters except whitespace
224           and quotes. This is useful for names like 'C++' and 'C#'.
225
226       type
227           Must be set to 'compiled' or 'interpreted'. Indicates the category
228           of the language.
229
230       suffix
231           This is the file extension for the cached object that will be
232           created.  For 'compiled' languages, it will probably be 'so' or
233           'dll'. The appropriate value is in "Config.pm".
234
235           For interpreted languages, this value can be whatever you want.
236           Python uses "pydat". Foo uses "foo".
237
238   The validate() Callback
239       This routine gets passed all configuration options that were not
240       already handled by the base Inline module. The options are passed as
241       key/value pairs. It is up to you to validate each option and store its
242       value in the Inline object (which is also passed in). If a particular
243       option is invalid, you should croak with an appropriate error message.
244
245   The build() Callback
246       This subroutine is responsible for doing the parsing and compilation of
247       the Foo source code. The Inline object is passed as the only argument.
248       All pertinent information will be stored in this object. "build()" is
249       required to create a cache object of a specific name, or to croak with
250       an appropriate error message.
251
252       This is the meat of your ILSM. Since it will most likely be quite
253       complicated, it is probably best that you study an existing ILSM like
254       "Inline::C".
255
256   The load() Callback
257       This method only needs to be provided for interpreted languages. It's
258       responsibility is to start the interpreter.
259
260       For compiled languages, the load routine from "Inline.pm" is called
261       which uses "DynaLoader" to load the shared object or DLL.
262
263   The info() Callback
264       This method is called when the user makes use of the "INFO" shortcut.
265       You should return a string containing a small report about the Inlined
266       code.
267

The Inline Object

269       "Inline.pm" creates a hash based Perl object for each section of
270       Inlined source code it receives. This object contains lots of
271       information about the code, the environment, and the configuration
272       options used.
273
274       This object is a hash that is broken into several subhashes. The only
275       two subhashes that an ILSM should use at all are $o->{API} and
276       $o->{ILSM}. The first one contains all of the information that Inline
277       has gather for you in order for you to create/load a cached object of
278       your design. The second one is a repository where your ILSM can freely
279       store data that it might need later on.
280
281       This section will describe all of the Inline object "API" attributes.
282
283   The code Attribute
284       This the actual source code passed in by the user. It is stored as one
285       long string.
286
287   The language Attribute
288       The proper name of the language being used.
289
290   The language_id Attribute
291       The language name specified by the user. Could be 'C++' instead of
292       'CPP'.
293
294   The module Attribute
295       This is the shared object's file name.
296
297   The modfname Attribute
298       This is the shared object's file name.
299
300   The modpname Attribute
301       This is the shared object's installation path extension.
302
303   The version Attribute
304       The version of "Inline.pm" being used.
305
306   The pkg Attribute
307       The Perl package from which this invocation pf Inline was called.
308
309   The install_lib Attribute
310       This is the directory to write the shared object into.
311
312   The build_dir Attribute
313       This is the directory under which you should write all of your build
314       related files.
315
316   The script Attribute
317       This is the name of the script that invoked Inline.
318
319   The location Attribute
320       This is the full path name of the executable object in question.
321
322   The suffix Attribute
323       This is the shared library extension name. (Usually 'so' or 'dll').
324

The Inline Namespace

326       "Inline.pm" has been set up so that anyone can write their own language
327       support modules. It further allows anyone to write a different
328       implementation of an existing Inline language, like C for instance. You
329       can distribute that module on the CPAN.
330
331       If you have plans to implement and distribute an Inline module, I would
332       ask that you please work with the Inline community. We can be reached
333       at the Inline mailing list: inline@perl.org (Send mail to
334       inline-subscribe@perl.org to subscribe). Here you should find the
335       advice and assistance needed to make your module a success.
336
337       The Inline community will decide if your implementation of COBOL will
338       be distributed as the official "Inline::COBOL" or should use an
339       alternate namespace. In matters of dispute, I (Brian Ingerson) retain
340       final authority. (and I hope not to need use of it :-) Actually
341       modules@perl.org retains the final authority.
342
343       But even if you want to work alone, you are free and welcome to write
344       and distribute Inline language support modules on CPAN. You'll just
345       need to distribute them under a different package name.
346

SEE ALSO

348       For generic information about Inline, see Inline.
349
350       For information about using Inline with C see Inline::C.
351
352       For information on supported languages and platforms see Inline-
353       Support.
354
355       Inline's mailing list is inline@perl.org
356
357       To subscribe, send email to inline-subscribe@perl.org
358

AUTHOR

360       Brian Ingerson <INGY@cpan.org>
361
363       Copyright (c) 2000, 2001, 2002. Brian Ingerson. All rights reserved.
364
365       This program is free software; you can redistribute it and/or modify it
366       under the same terms as Perl itself.
367
368       See http://www.perl.com/perl/misc/Artistic.html
369
370
371
372perl v5.12.1                      2010-01-27                     Inline-API(3)
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