Ubuntu Manpage: Inline - Write Perl subroutines in other programming languages.

NAME

       Inline - Write Perl subroutines in other programming languages.

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.

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 trys 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 congiguration 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, "Event" is the only module that works with 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. 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.

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 considerd 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 shorcut 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
shorcuts 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 C/t/09parser.t and C/t/10callback.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

       Writing CPAN modules that use C code is easy with Inline. 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 $VERSION variable
       and they must be of the form "/^\d\.\d\d$/".

       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:

           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:

1) 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.

2) 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)

3) 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:

A) The DIRECTORY= config option; if specified
B) The PERL_INLINE_DIRECTORY environment variable; if set
C) .Inline/ (in current directory); if exists and $PWD != $HOME
D) bin/.Inline/ (in directory of your script); if exists
E) ~/.Inline/; if exists
F) ./_Inline/; if exists
G) bin/_Inline; if exists
H) Create ./_Inline/; if possible
I) 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.

4) 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.

5) 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".

6) 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.

7) 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.

8) 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

       Brian Ingerson <INGY@cpan.org>

       Neil  Watkiss  <NEILW@cpan.org>  is  the  author  of  "Inline::CPP",  "Inline::Python",   "Inline::Ruby",
       "Inline::ASM", "Inline::Struct" and "Inline::Filters". He is known in the innermost Inline circles as the
       "Boy Wonder".

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

COPYRIGHT

       Copyright (c) 2000-2002. Brian Ingerson.

       Copyright (c) 2008, 2010-2013. 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

perl v5.18.1                                       2013-04-10                                        Inline(3pm)

NAME

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