NAME

    Inline - Write Perl Subroutines in Other Programming Languages

VERSION

    This document describes Inline version 0.83.

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 ... */

      or

          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;
    
        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.

 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, Event is the only module that works with Inline.

    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

    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.

    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();
    
        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:

      * 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";

      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.

      * 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.

SEE ALSO

    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

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

