Ubuntu Manpage: Inline - Write Perl Subroutines in Other Programming Languages

NAME

       Inline - Write Perl Subroutines in Other Programming Languages

VERSION

       This document describes Inline version 0.86.

SYNOPSIS

           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;
           }

DESCRIPTION

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.

Why Inline?
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.

Why would I use other languages in Perl?
The most obvious reason is performance. For an interpreted language, Perl is very
fast. Many people will say "Anything Perl can do, C can do faster". (They never
mention the development time :-) Anyway, you may be able to remove a bottleneck in
your Perl code by using another language, without having to write the entire program
in that language. This keeps your overall development time down, because you're using
Perl for all of the non-critical code.

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!

Why should I use Inline to do it?
There are already two major facilities for extending Perl with C. They are XS and
SWIG. Both are similar in their capabilities, at least as far as Perl is concerned.
And both of them are quite difficult to learn compared to Inline.

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:

• perlxs

• perlxstut

• perlapi

• perlguts

• perlmod

• h2xs

• xsubpp

• ExtUtils::MakeMaker

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.

USING THE INLINE.PM MODULE

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 Basics
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:

The DATA Keyword.
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.

The FILE and BELOW keywords.
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.

Strings
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 ...

The bind() Function
An alternative to using the BEGIN block method is to specify the source code at run
time using the 'Inline->bind()' method. (This is one of the interface exceptions
mentioned above) The "bind()" method takes the same arguments as 'use Inline ...'.

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.

Other Methods
The source code for Inline can also be specified as an external filename, a reference
to a subroutine that returns source code, or a reference to an array that contains
lines of source code. (Note that if the external source file is in the current
directory it must be specified with a leading '.' - ie '.file.ext' instead of simply
'file.ext'.) These methods are less frequently used but may be useful in some
situations.

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);

Shorthand
If you are using the 'DATA' or 'file' methods described above and there are no extra
parameters, you can omit the keyword altogether. For example:

use Inline 'Java';

# Perl code goes here ...

__DATA__
__Java__
/* Java code goes here ... */

use Inline::Files;
use Inline 'Java';

# Perl code goes here ...

__JAVA__
/* Java code goes here ... */

More about the DATA Section
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;

__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.

Configuration Options
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".

On and Off
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;

Playing 'with' Others
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 Shortcuts
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

The Inline 'directory'
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/".

Debugging Inline Errors
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.

The 'config' Registry File
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.)

CONFIGURATION OPTIONS

This section lists all of the generic Inline configuration options. For language specific
configuration, see the doc for that language.

"directory"
The "directory" config option is the directory that Inline uses to both build and
install an extension.

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.

"name"
You can use this option to set the name of your Inline extension object module. For
example:

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.

"autoname"
This option is enabled whenever the "name" parameter is not specified. To disable it
say:

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.

"version"
Specifies the version number of the Inline extension object. It is used only for
modules, and it must match the global variable $VERSION. Additionally, this option
should used if (and only if) a module is being set up to be installed permanently into
the Perl sitelib tree using Inline::MakeMaker (NOT used by Inline::Module). Inline
will croak if you use it otherwise.

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".

"with"
"with" can also be used as a configuration option instead of using the special 'with'
syntax. Do this if you want to use different sections of Inline code with different
modules. (Probably a very rare usage)

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.

"using"
You can override modules that get used by ILSMs with the "using" option. This is
typically used to override the default parser for Inline::C, but might be used by any
ILSM for any purpose.

use Inline config => using => '::Parser::RecDescent';
use Inline C => '...';

This would tell Inline::C to use Inline::C::Parser::RecDescent.

"global_load"
This option is for compiled languages only. It tells Inline to tell DynaLoader to load
an object file in such a way that its symbols can be dynamically resolved by other
object files. May not work on all platforms. See the "global" shortcut below.

"untaint"
You can use this option whenever you use Perl's "-T" switch, for taint checking. This
option tells Inline to blindly untaint all tainted variables. (This is generally
considered to be an appallingly insecure thing to do, and not to be recommended - but
the option is there for you to use if you want. Please consider using something other
than Inline for scripts that need taint checking.) It also turns on "safemode" by
default. See the "untaint" shortcut below. You will see warnings about blindly
untainting fields in both %ENV and Inline objects. If you want to silence these
warnings, set the Config option "no_untaint_warn" => 1. There can be some problems
untainting Inline scripts where older versions of Cwd, such as those that shipped with
early versions of perl-5.8 (and earlier), are installed. Updating Cwd will probably
solve these problems.

safemode
Perform extra safety checking, in an attempt to thwart malicious code. This option
cannot guarantee security, but it does turn on all the currently implemented checks.
(Currently, the only "currently implemented check" is to ensure that the "directory"
option has also been used.)

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.

"force_build"
Makes Inline build (compile) the source code every time the program is run. The
default is 0. See the "force" shortcut below.

"build_noisy"
Tells ILSMs that they should dump build messages to the terminal rather than be silent
about all the build details.

"build_timers"
Tells ILSMs to print timing information about how long each build phase took. Usually
requires "Time::HiRes".

"clean_after_build"
Tells Inline to clean up the current build area if the build was successful.
Sometimes you want to "disable" this for debugging. Default is 1. See the "noclean"
shortcut below.

"clean_build_area"
Tells Inline to clean up the old build areas within the entire Inline "directory".
Default is 0. See the "clean" shortcut below.

"print_info"
Tells Inline to print various information about the source code. Default is 0. See
the "info" shortcut below.

"print_version"
Tells Inline to print version info about itself. Default is 0. See the "version"
shortcut below.

"reportbug"
Puts Inline into 'reportbug' mode, which is what you want if you desire to report a
bug.

"rewrite_config_file"
Default is 0, but setting "rewrite_config_file => 1" will mean that the existing
configuration file in the Inline "directory" will be overwritten. (This is useful if
the existing config file is not up to date as regards supported languages.)

"warnings"
This option tells Inline whether to print certain warnings. Default is 1.

INLINE CONFIGURATION SHORTCUTS

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

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.

"clean"
Tells Inline to remove any build directories that may be lying around in your build
area. Normally these directories get removed immediately after a successful build.
Exceptions are when the build fails, or when you use the "noclean" or "reportbug"
options.

"force"
Forces the code to be recompiled, even if everything is up to date.

"global"
Turns on the "global_load" option.

"info"
This is a very useful option when you want to know what's going on under the hood. It
tells Inline to print helpful information to "STDERR". Among the things that get
printed is a list of which Inline functions were successfully bound to Perl.

"noclean"
Tells Inline to leave the build files after compiling.

"noisy"
Use the "build_noisy" option to print messages during a build.

"reportbug"
Puts Inline into "reportbug" mode, which does special processing when you want to
report a bug. "reportbug" also automatically forces a build, and doesn't clean up
afterwards. This is so that you can tar and mail the build directory to me.
"reportbug" will print exact instructions on what to do. Please read and follow them
carefully.

NOTE: "reportbug" informs you to use the tar command. If your system does not
have tar, please use the equivalent "zip" command.

"safe"
Turns "safemode" on. "untaint" will turn this on automatically. While this mode
performs extra security checking, it does not guarantee safety.

"site_install"
This parameter used to be used for creating installable Inline modules. It has been
removed from Inline altogether and replaced with a much simpler and more powerful
mechanism, "Inline::MakeMaker". See the section below on how to create modules with
Inline.

"_testing"
Used internally by Ct09parser.t and Ct10callback.t(in the Inline::C test suite).
Setting this option with Inline::C will mean that files named "parser_id" and
"void_test" are created in the "./Inline_test" directory, creating that directory if
it doesn't already exist. The files (but not the "./Inline_test directory") are
cleaned up by calling "Inline::C::_testing_cleanup()". Also used by
"t/06rewrite_config.t" to trigger a warning.

"timers"
Turn on "build_timers" to get extra diagnostic info about builds.

"unsafe"
Turns "safemode" off. Use this in combination with "untaint" for slightly faster
startup time under "-T". Only use this if you are sure the environment is safe.

"untaint"
Turn the "untaint" option on. Used with "-T" switch. In terms of secure practices,
this is definitely not a recommended way of dealing with taint checking, but it's the
only option currently available with Inline. Use it at your own risk.

"version"
Tells Inline to report its release version.

WRITING MODULES WITH INLINE

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();

__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;

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:

• perldoc perlnewmod

• <http://www.cpan.org/modules/04pause.html>

• <http://www.cpan.org/modules/00modlist.long.html>

HOW INLINE WORKS

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:

• Receive the Source Code

Inline gets the source code from your script or module with a statements like the
following:

use Inline C => "Source-Code";

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.

• Check if the Source Code has been Built

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)

• Find a Place to Build and Install

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:

1. The DIRECTORY= config option; if specified

2. The "PERL_INLINE_DIRECTORY" environment variable; if set

3. ".Inline/" (in current directory); if exists and "$PWD != $HOME"

4. bin.Inline (in directory of your script); if exists

5. "~/.Inline/" - if exists

6. "./_Inline/" - if exists

7. "bin/_Inline" - if exists

8. Create "./_Inline/" - if possible

9. Create "bin/_Inline/" - if possible

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.

• Parse the Source for Semantic Cues

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.

• Create the Build Environment

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".

• Build the Code and Install the Executable

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.

• Tidy Up

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.

• DynaLoad the Executable

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.

BUGS AND DEFICIENCIES

       When reporting a bug, please do the following:

       •   Put "use Inline 'reportbug';" at the top of your code, or use the command line option
           "perl -MInline=reportbug ...".

       •   Run your code.

       •   Follow the printed directions.

AUTHOR

       Ingy döt Net <ingy@cpan.org>

       Sisyphus <sisyphus@cpan.org> fixed some bugs and is current co-maintainer.

COPYRIGHT

       •   Copyright 2000-2019. Ingy döt Net.

       •   Copyright 2008, 2010-2014. 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>

NAME

VERSION

SYNOPSIS

DESCRIPTION

USING THE INLINE.PM MODULE

CONFIGURATION OPTIONS

INLINE CONFIGURATION SHORTCUTS

WRITING MODULES WITH INLINE

HOW INLINE WORKS

SEE ALSO

BUGS AND DEFICIENCIES

AUTHOR

COPYRIGHT