| Inline(3pm) | User Contributed Perl Documentation | Inline(3pm) |
Inline - Write Perl Subroutines in Other Programming Languages
This document describes Inline version 0.86.
use Inline C;
print "9 + 16 = ", add(9, 16), "\n";
print "9 - 16 = ", subtract(9, 16), "\n";
__END__
__C__
int add(int x, int y) {
return x + y;
}
int subtract(int x, int y) {
return x - y;
}
The Inline module allows you to put source code from other programming languages directly "inline" in a Perl script or module. The code is automatically compiled as needed, and then loaded for immediate access from Perl.
Inline saves you from the hassle of having to write and compile your own glue code using facilities like XS or SWIG. Simply type the code where you want it and run your Perl as normal. All the hairy details are handled for you. The compilation and installation of your code chunks all happen transparently; all you will notice is the delay of compilation on the first run.
The Inline code only gets compiled the first time you run it (or whenever it is modified) so you only take the performance hit once. Code that is Inlined into distributed modules (like on the CPAN) will get compiled when the module is installed, so the end user will never notice the compilation time.
Best of all, it works the same on both Unix and Microsoft Windows. See Inline- Support for support information.
Do you want to know "Why would I use other languages in Perl?" or "Why should I use Inline to do it?"? I'll try to answer both.
Another reason is to access functionality from existing API-s that use the language. Some of this code may only be available in binary form. But by creating small subroutines in the native language, you can "glue" existing libraries to your Perl. As a user of the CPAN, you know that code reuse is a good thing. So why throw away those Fortran libraries just yet?
If you are using Inline with the C language, then you can access the full internals of Perl itself. This opens up the floodgates to both extreme power and peril.
Maybe the best reason is "Because you want to!". Diversity keeps the world interesting. TMTOWTDI!
There is a big fat learning curve involved with setting up and using the XS environment. You need to get quite intimate with the following docs:
With Inline you can be up and running in minutes. There is a C Cookbook with lots of short but complete programs that you can extend to your real-life problems. No need to learn about the complicated build process going on in the background. You don't even need to compile the code yourself. Inline takes care of every last detail except writing the C code.
Perl programmers cannot be bothered with silly things like compiling. "Tweak, Run, Tweak, Run" is our way of life. Inline does all the dirty work for you.
Another advantage of Inline is that you can use it directly in a script. You can even use it in a Perl one-liner. With XS and SWIG, you always set up an entirely separate module. Even if you only have one or two functions. Inline makes easy things easy, and hard things possible. Just like Perl.
Finally, Inline supports several programming languages (not just C and C++). As of this writing, Inline has support for C, C++, Java, Python, Ruby, Tcl, Assembler, Basic, Guile, Befunge, Octave, Awk, BC, TT (Template Toolkit), WebChat and even PERL. New Inline Language Support Modules (ILSMs) are regularly being added. See Inline-API for details on how to create your own ILSM.
Inline is a little bit different than most of the Perl modules that you are used to. It doesn't import any functions into your namespace and it doesn't have any object oriented methods. Its entire interface (with two minor exceptions) is specified through the 'use Inline ...' command.
This section will explain all of the different ways to "use Inline". If you want to begin using C with Inline immediately, see Inline::C-Cookbook.
The most basic form for using Inline is:
use Inline X => "X source code";
where 'X' is one of the supported Inline programming languages. The second parameter identifies the source code that you want to bind to Perl. The source code can be specified using any of the following syntaxes:
use Inline Java => 'DATA';
# Perl code goes here ...
__DATA__
__Java__
/* Java code goes here ... */
The easiest and most visually clean way to specify your source code in an Inline Perl program is to use the special "DATA" keyword. This tells Inline to look for a special marker in your "DATA" filehandle's input stream. In this example the special marker is "__Java__", which is the programming language surrounded by double underscores.
In case you've forgotten, the "DATA" pseudo file is comprised of all the text after the "__END__" or "__DATA__" section of your program. If you're working outside the "main" package, you'd best use the "__DATA__" marker or else Inline will not find your code.
Using this scheme keeps your Perl code at the top, and all the ugly Java stuff down below where it belongs. This is visually clean and makes for more maintainable code. An excellent side benefit is that you don't have to escape any characters like you might in a Perl string. The source code is verbatim. For these reasons, I prefer this method the most.
The only problem with this style is that since Perl can't read the "DATA" filehandle until runtime, it obviously can't bind your functions until runtime. The net effect of this is that you can't use your Inline functions as barewords (without predeclaring them) because Perl has no idea they exist during compile time.
use Inline::Files;
use Inline Java => 'file';
# Perl code goes here ...
__JAVA__
/* Java code goes here ... */
This is the newest method of specifying your source code. It makes use of the Perl module "Inline::Files" written by Damian Conway. The basic style and meaning are the same as for the "DATA" keyword, but there are a few syntactic and semantic twists.
First, you must say 'use Inline::Files' before you 'use Inline' code that needs those files. The special '"DATA"' keyword is replaced by either '"file"' or '"below"'. This allows for the bad pun idiom of:
use Inline C => 'below';
You can omit the "__DATA__" tag now. Inline::Files is a source filter that will remove these sections from your program before Perl compiles it. They are then available for Inline to make use of. And since this can all be done at compile time, you don't have to worry about the caveats of the 'DATA' keyword.
This module has a couple small gotchas. Since Inline::Files only recognizes file markers with capital letters, you must specify the capital form of your language name. Also, there is a startup time penalty for using a source code filter.
At this point Inline::Files is alpha software and use of it is experimental. Inline's integration of this module is also fledgling at the time being. One of things I plan to do with Inline::Files is to get line number info so when an extension doesn't compile, the error messages will point to the correct source file and line number.
My best advice is to use Inline::Files for testing (especially as support for it improves), but use DATA for production and distributed/CPAN code.
use Inline Java => <<'END';
/* Java code goes here ... */
END
# Perl code goes here ...
You also just specify the source code as a single string. A handy way to write the string is to use Perl's "here document" style of quoting. This is ok for small functions but can get unwieldy in the large. On the other hand, the string variant probably has the least startup penalty and all functions are bound at compile time.
If you wish to put the string into a scalar variable, please be aware that the "use" statement is a compile time directive. As such, all the variables it uses must also be set at compile time, "before" the 'use Inline' statement. Here is one way to do it:
my $code;
BEGIN {
$code = <<END;
/* Java code goes here ... */
END
}
use Inline Java => $code;
# Perl code goes here ...
my $code = <<END;
/* Java code goes here ... */
END
Inline->bind(Java => $code);
You can think of "bind()" as a way to "eval()" code in other programming languages.
Although bind() is a powerful feature, it is not recommended for use in Inline based modules. In fact, it won't work at all for installable modules. See instructions below for creating modules with Inline.
For instance, to load your C++ code from a file named the same as your perl module with a swapped file extension, you can use:
use Inline CPP => (__FILE__ =~ s/\.pm$/.cpp/r);
use Inline 'Java';
# Perl code goes here ...
__DATA__
__Java__
/* Java code goes here ... */
or
use Inline::Files;
use Inline 'Java';
# Perl code goes here ...
__JAVA__
/* Java code goes here ... */
If you are writing a module, you can also use the DATA section for POD and AutoLoader subroutines. Just be sure to put them before the first Inline marker. If you install the helper module "Inline::Filters", you can even use POD inside your Inline code. You just have to specify a filter to strip it out.
You can also specify multiple Inline sections, possibly in different programming languages. Here is another example:
# The module Foo.pm
package Foo;
use AutoLoader;
use Inline C;
use Inline C => DATA => filters => 'Strip_POD';
use Inline Python;
1;
__DATA__
sub marine {
# This is an autoloaded subroutine
}
=head1 External subroutines
=cut
__C__
/* First C section */
__C__
/* Second C section */
=head1 My C Function
Some POD doc.
=cut
__Python__
"""A Python Section"""
An important thing to remember is that you need to have one "use Inline Foo => 'DATA'" for each "__Foo__" marker, and they must be in the same order. This allows you to apply different configuration options to each section.
Inline tries to do the right thing as often as possible. But sometimes you may need to override the default actions. This is easy to do. Simply list the Inline configuration options after the regular Inline parameters. All configuration options are specified as (key, value) pairs.
use Inline (C => 'DATA',
directory => './inline_dir',
libs => '-lfoo',
inc => '-I/foo/include',
prefix => 'XXX_',
warnings => 0,
);
You can also specify the configuration options on a separate Inline call like this:
use Inline (C => Config =>
directory => './inline_dir',
libs => '-lfoo',
inc => '-I/foo/include',
prefix => 'XXX_',
warnings => 0,
);
use Inline C => <<'END_OF_C_CODE';
The special keyword 'Config' tells Inline that this is a configuration-only call. No source code will be compiled or bound to Perl.
If you want to specify global configuration options that don't apply to a particular language, just leave the language out of the call. Like this:
use Inline Config => warnings => 0;
The Config options are inherited and additive. You can use as many Config calls as you want. And you can apply different options to different code sections. When a source code section is passed in, Inline will apply whichever options have been specified up to that point. Here is a complex configuration example:
use Inline (Config =>
directory => './inline_dir',
);
use Inline (C => Config =>
libs => '-lglobal',
);
use Inline (C => 'DATA', # First C Section
libs => ['-llocal1', '-llocal2'],
);
use Inline (Config =>
warnings => 0,
);
use Inline (Python => 'DATA', # First Python Section
libs => '-lmypython1',
);
use Inline (C => 'DATA', # Second C Section
libs => [undef, '-llocal3'],
);
The first "Config" applies to all subsequent calls. The second "Config" applies to all subsequent "C" sections (but not "Python" sections). In the first "C" section, the external libraries "global", "local1" and "local2" are used. (Most options allow either string or array ref forms, and do the right thing.) The "Python" section does not use the "global" library, but does use the same "DIRECTORY", and has warnings turned off. The second "C" section only uses the "local3" library. That's because a value of "undef" resets the additive behavior.
The "directory" and "warnings" options are generic Inline options. All other options are language specific. To find out what the "C" options do, see "Inline::C".
If a particular config option has value options of 1 and 0, you can use the 'enable' and 'disable' modifiers. In other words, this:
use Inline Config =>
force_build => 1,
clean_after_build => 0;
could be reworded as:
use Inline Config =>
enable => force_build =>
disable => clean_after_build;
Inline has a special configuration syntax that tells it to get more configuration options from other Perl modules. Here is an example:
use Inline with => 'Event';
This tells Inline to load the module "Event.pm" and ask it for configuration information. Since "Event" has a C API of its own, it can pass Inline all of the information it needs to be able to use "Event" C callbacks seamlessly.
That means that you don't need to specify the typemaps, shared libraries, include files and other information required to get this to work.
You can specify a single module or a list of them. Like:
use Inline with => qw(Event Foo Bar);
Currently, modules that works with Inline include "Event", "PDL", and those that use "Alien::Build".
In order to make your module work with Inline in this way, your module needs to provide a class method called "Inline" that takes an Inline language as a parameter (e.g. "C"), and returns a reference to a hash with configuration information that is acceptable to the relevant ILSM. For C, see C Configuration Options. E.g.:
my $confighashref = Event->Inline('C'); # only supports C in 1.21
# hashref contains keys INC, TYPEMAPS, MYEXTLIB, AUTO_INCLUDE, BOOT
If your module uses ExtUtils::Depends version 0.400 or higher, your module only needs this:
package Module;
use autouse Module::Install::Files => qw(Inline);
Inline lets you set many configuration options from the command line. These options are called 'shortcuts'. They can be very handy, especially when you only want to set the options temporarily, for say, debugging.
For instance, to get some general information about your Inline code in the script "Foo.pl", use the command:
perl -MInline=info Foo.pl
If you want to force your code to compile, even if its already done, use:
perl -MInline=force Foo.pl
If you want to do both, use:
perl -MInline=info -MInline=force Foo.pl
or better yet:
perl -MInline=info,force Foo.pl
Inline needs a place to build your code and to install the results of the build. It uses a single directory named '.Inline/' under normal circumstances. If you create this directory in your home directory, the current directory or in the directory where your program resides, Inline will find and use it. You can also specify it in the environment variable "PERL_INLINE_DIRECTORY" or directly in your program, by using the "directory" keyword option. If Inline cannot find the directory in any of these places it will create a '_Inline/' directory in either your current directory or the directory where your script resides.
One of the key factors to using Inline successfully, is understanding this directory. When developing code it is usually best to create this directory (or let Inline do it) in your current directory. Remember that there is nothing sacred about this directory except that it holds your compiled code. Feel free to delete it at any time. Inline will simply start from scratch and recompile your code on the next run. If you have several programs that you want to force to recompile, just delete your '.Inline/' directory.
It is probably best to have a separate '.Inline/' directory for each project that you are working on. You may want to keep stable code in the <.Inline/> in your home directory. On multi-user systems, each user should have their own '.Inline/' directories. It could be a security risk to put the directory in a shared place like "/tmp/".
All programmers make mistakes. When you make a mistake with Inline, like writing bad C code, you'll get a big error report on your screen. This report tells you where to look to do the debugging. Some languages may also dump out the error messages generated from the build.
When Inline needs to build something it creates a subdirectory under your "DIRECTORY/build/" directory. This is where it writes all the components it needs to build your extension. Things like XS files, Makefiles and output log files.
If everything goes OK, Inline will delete this subdirectory. If there is an error, Inline will leave the directory intact and print its location. The idea is that you are supposed to go into that directory and figure out what happened.
Read the doc for your particular Inline Language Support Module for more information.
Inline keeps a cached file of all of the Inline Language Support Module's meta data in a file called "config". This file can be found in your "directory" directory. If the file does not exist, Inline creates a new one. It will search your system for any module beginning with "Inline::". It will then call that module's "register()" method to get useful information for future invocations.
Whenever you add a new ILSM, you should delete this file so that Inline will auto-discover your newly installed language module. (This should no longer be necessary as of Inline-0.49.)
This section lists all of the generic Inline configuration options. For language specific configuration, see the doc for that language.
Normally Inline will search in a bunch of known places for a directory called '.Inline/'. Failing that, it will create a directory called '_Inline/'
If you want to specify your own directory, use this configuration option.
Note that you must create the "directory" directory yourself. Inline will not do it for you.
use Inline C => 'DATA',
name => 'Foo::Bar';
would cause your C code to be compiled in to the object:
lib/auto/Foo/Bar/Bar.so
lib/auto/Foo/Bar/Bar.inl
(The .inl component contains dependency information to make sure the source code is in sync with the executable)
If you don't use "name", Inline will pick a name for you based on your program name or package name. In this case, Inline will also enable the "autoname" option which mangles in a small piece of the MD5 fingerprint into your object name, to make it unique.
use Inline C => 'DATA',
disable => 'autoname';
"autoname" mangles in enough of the MD5 fingerprint to make your module name unique. Objects created with "autoname" will never get replaced. That also means they will never get cleaned up automatically.
"autoname" is very useful for small throw away scripts. For more serious things, always use the "name" option.
The presence of the "version" parameter is the official way to let Inline know that your code is an installable/installed module. Inline will never generate an object in the temporary cache ("_Inline/" directory) if "version" is set. It will also never try to recompile a module that was installed into someone's Perl site tree.
So the basic rule is develop without "version", and deliver with "version".
use Event;
use Inline C => DATA => with => 'Event';
Modules specified using the config form of "with" will not be automatically required. You must "use" them yourself.
use Inline config => using => '::Parser::RecDescent';
use Inline C => '...';
This would tell Inline::C to use Inline::C::Parser::RecDescent.
There is a slight startup penalty by using "safemode". Also, using "untaint" automatically turns this option on. If you need your code to start faster under "-T" (taint) checking, you'll need to turn this option off manually. Only do this if you are not worried about security risks. See the "unsafe" shortcut below.
This is a list of all the shortcut configuration options currently available for Inline. Specify them from the command line when running Inline scripts.
perl -MInline=noclean inline_script.pl
or
perl -MInline=info,force,noclean inline_script.pl
You can specify multiple shortcuts separated by commas. They are not case sensitive. You can also specify shortcuts inside the Inline program like this:
use Inline 'info', 'force', 'noclean';
NOTE: If a 'use Inline' statement is used
to set shortcuts, it can not be
used for additional purposes.
NOTE: "reportbug" informs
you to use the tar command. If your system does not
have tar, please use the equivalent
"zip" command.
The current preferred way to author CPAN modules with Inline is to use Inline::Module (distributed separately). Inline ships with Inline::MakeMaker, which helps you set up a Makefile.PL that invokes Inline at install time to compile all the code before it gets installed, but the resulting module still depends on Inline and the language support module like Inline::C. In order to avoid this dependency, what you really want to do is convert your distribution to plain XS before uploading it to CPAN. Inline::Module fills that role, and also integrates well with more modern authoring tools.
See Inline::Module for details on that approach, or continue reading below for the older Inline::MakeMaker technique.
Let's say that you wanted to write a module called "Math::Simple". Start by using the following command:
h2xs -PAXn Math::Simple
This will generate a bunch of files that form a skeleton of what you need for a distributable module. (Read the h2xs manpage to find out what the options do) Next, modify the "Simple.pm" file to look like this:
package Math::Simple;
$VERSION = '1.23';
use base 'Exporter';
@EXPORT_OK = qw(add subtract);
use strict;
use Inline C => 'DATA',
version => '1.23',
name => 'Math::Simple';
# The following Inline->init() call is optional - see below for more info.
#Inline->init();
1;
__DATA__
=pod
=cut
__C__
int add(int x, int y) {
return x + y;
}
int subtract(int x, int y) {
return x - y;
}
The important things to note here are that you must specify a "name" and "version" parameter. The "name" must match your module's package name. The "version" parameter must match your module's $VERSION variable and they must be considered valid by "version::parse".
NOTE: These are Inline's sanity checks to make sure you know what
you're doing
before uploading your code to CPAN. They insure that once the module has
been installed on someone's system, the module would not get
automatically recompiled for any reason. This makes Inline based modules
work in exactly the same manner as XS based ones.
Finally, you need to modify the Makefile.PL. Simply change:
use ExtUtils::MakeMaker;
to
use Inline::MakeMaker;
And, in order that the module build work correctly in the cpan shell, add the following directive to the Makefile.PL's WriteMakefile():
CONFIGURE_REQUIRES => {
'Inline::MakeMaker' => 0.45,
'ExtUtils::MakeMaker' => 6.52,
},
This "CONFIGURE_REQUIRES" directive ensures that the cpan shell will install Inline on the user's machine (if it's not already present) before building your Inline-based module. Specifying of "ExtUtils::MakeMaker => 6.52," is optional, and can be omitted if you like. It ensures only that some harmless warnings relating to the "CONFIGURE_REQUIRES" directive won't be emitted during the building of the module. It also means, of course, that ExtUtils::Makemaker will first be updated on the user's machine unless the user already has version 6.52 or later.
If the "Inline->init();" is not done then, having installed Math::Simple, a warning that "One or more DATA sections were not processed by Inline" will appear when (and only when) Math::Simple is loaded by a "require call. It's a harmless warning - and if you're prepared to live with it, then there's no need to make the "Inline->init();" call.
When the person installing "Math::Simple" does a ""make"", the generated Makefile will invoke Inline in such a way that the C code will be compiled and the executable code will be placed into the "./blib" directory. Then when a ""make install"" is done, the module will be copied into the appropriate Perl sitelib directory (which is where an installed module should go).
Now all you need to do is:
perl Makefile.PL
make dist
That will generate the file "Math-Simple-0.20.tar.gz" which is a distributable package. (It will also generate some harmless warnings in relation to "CONFIGURE_REQUIRES" unless the version of your ExtUtils::MakeMaker is 6.52 or later.) That's all there is to it.
IMPORTANT NOTE: Although the above steps will produce a workable module, you still have a few more responsibilities as a budding new CPAN author. You need to write lots of documentation and write lots of tests. Take a look at some of the better CPAN modules for ideas on creating a killer test harness. Actually, don't listen to me, go read these:
In reality, Inline just automates everything you would need to do if you were going to do it by hand (using XS, etc).
Inline performs the following steps:
Inline gets the source code from your script or module with a statements like the following:
use Inline C => "Source-Code";
or
use Inline;
bind Inline C => "Source-Code";
where "C" is the programming language of the source code, and "Source- Code" is a string, a file name, an array reference, or the special 'DATA' keyword.
Since Inline is coded in a ""use"" statement, everything is done during Perl's compile time. If anything needs to be done that will affect the "Source- Code", it needs to be done in a "BEGIN" block that is before the ""use Inline ..."" statement. If you really need to specify code to Inline at runtime, you can use the "bind()" method.
Source code that is stowed in the 'DATA' section of your code, is read in by an "INIT" subroutine in Inline. That's because the "DATA" filehandle is not available at compile time.
Inline only needs to build the source code if it has not yet been built. It accomplishes this seemingly magical task in an extremely simple and straightforward manner. It runs the source text through the "Digest::MD5" module to produce a 128-bit "fingerprint" which is virtually unique. The fingerprint along with a bunch of other contingency information is stored in a ".inl" file that sits next to your executable object. For instance, the "C" code from a script called "example.pl" might create these files:
example_pl_3a9a.so
example_pl_3a9a.inl
If all the contingency information matches the values stored in the ".inl" file, then proceed to step 8. (No compilation is necessary)
At this point Inline knows it needs to build the source code. The first thing to figure out is where to create the great big mess associated with compilation, and where to put the object when it's done.
By default Inline will try to build and install under the first place that meets one of the following conditions:
Failing that, Inline will croak. This is rare and easily remedied by just making a directory that Inline will use.
If the "PERL_INSTALL_ROOT" Environment Variable has been set, you will need to make special provision for that if the 'make install' phase of your Inline scripts are to succeed.
If the module option is being compiled for permanent installation, then Inline will only use "./_Inline/" to build in, and the $Config{installsitearch} directory to install the executable in. This action is caused by Inline::MakeMaker, and is intended to be used in modules that are to be distributed on the CPAN, so that they get installed in the proper place.
Inline::C uses the module "Parse::RecDescent" to parse through your chunks of C source code and look for things that it can create run-time bindings to. In "C" it looks for all of the function definitions and breaks them down into names and data types. These elements are used to correctly bind the "C" function to a "Perl" subroutine. Other Inline languages like Python and Java actually use the "python" and "javac" modules to parse the Inline code.
Now Inline can take all of the gathered information and create an environment to build your source code into an executable. Without going into all the details, it just creates the appropriate directories, creates the appropriate source files including an XS file (for C) and a "Makefile.PL".
The planets are in alignment. Now for the easy part. Inline just does what you would do to install a module. "`perl Makefile.PL && make && make test && make install>". If something goes awry, Inline will croak with a message indicating where to look for more info.
By default, Inline will remove all of the mess created by the build process, assuming that everything worked. If the build fails, Inline will leave everything intact, so that you can debug your errors. Setting the "noclean" shortcut option will also stop Inline from cleaning up.
For C (and C++), Inline uses the "DynaLoader::bootstrap" method to pull your external module into "Perl" space. Now you can call all of your external functions like Perl subroutines.
Other languages like Python and Java, provide their own loaders.
For information about using Inline with C see Inline::C.
For sample programs using Inline with C see Inline::C-Cookbook.
For "Formerly Answered Questions" about Inline, see Inline-FAQ.
For information on supported languages and platforms see Inline-Support.
For information on writing your own Inline Language Support Module, see Inline-API.
Inline's mailing list is inline@perl.org
To subscribe, send email to inline-subscribe@perl.org
When reporting a bug, please do the following:
Ingy döt Net <ingy@cpan.org>
Sisyphus <sisyphus@cpan.org> fixed some bugs and is current co-maintainer.
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>
| 2020-01-12 | perl v5.30.0 |