Provided by: libffi-platypus-perl_1.10-1_amd64 bug

NAME

       FFI::Platypus - Write Perl bindings to non-Perl libraries with FFI. No XS required.

VERSION

       version 1.10

SYNOPSIS

        use FFI::Platypus;

        # for all new code you should use api => 1
        my $ffi = FFI::Platypus->new( api => 1 );
        $ffi->lib(undef); # search libc

        # call dynamically
        $ffi->function( puts => ['string'] => 'int' )->call("hello world");

        # attach as a xsub and call (much faster)
        $ffi->attach( puts => ['string'] => 'int' );
        puts("hello world");

DESCRIPTION

       Platypus is a library for creating interfaces to machine code libraries written in languages like C, C++,
       Fortran, Rust, Pascal. Essentially anything that gets compiled into machine code.  This implementation
       uses "libffi" to accomplish this task.  "libffi" is battle tested by a number of other scripting and
       virtual machine languages, such as Python and Ruby to serve a similar role.  There are a number of
       reasons why you might want to write an extension with Platypus instead of XS:

       FFI / Platypus does not require messing with the guts of Perl
           XS  is  less of an API and more of the guts of perl splayed out to do whatever you want.  That may at
           times be very powerful, but it can also be a frustrating exercise in hair pulling.

       FFI / Platypus is portable
           Lots of languages have FFI interfaces, and it is subjectively easier to port an extension written  in
           FFI in Perl or another language to FFI in another language or Perl.  One goal of the Platypus Project
           is  to  reduce  common  interface  specifications  to  a common format like JSON that could be shared
           between different languages.

       FFI / Platypus could be a bridge to Perl 6
           One of those "other" languages could be Perl 6 and Perl 6 already has an FFI interface I am told.

       FFI / Platypus can be reimplemented
           In a bright future with multiple implementations of Perl  5,  each  interpreter  will  have  its  own
           implementation of Platypus, allowing extensions to be written once and used on multiple platforms, in
           much the same way that Ruby-FFI extensions can be use in Ruby, JRuby and Rubinius.

       FFI / Platypus is pure perl (sorta)
           One  Platypus script or module works on any platform where the libraries it uses are available.  That
           means you can deploy your Platypus script in a shared filesystem where they may be run  on  different
           platforms.   It also means that Platypus modules do not need to be installed in the platform specific
           Perl library path.

       FFI / Platypus is not C or C++ centric
           XS is implemented primarily as a bunch of C macros, which requires at least some understanding of  C,
           the C pre-processor, and some C++ caveats (since on some platforms Perl is compiled and linked with a
           C++  compiler).  Platypus  on  the  other  hand  could be used to call other compiled languages, like
           Fortran, Rust, Pascal, C++, or even assembly, allowing you to focus on your strengths.

       FFI / Platypus does not require a parser
           Inline isolates the extension developer from XS to some extent, but it also requires a  parser.   The
           various  Inline language bindings are a great technical achievement, but I think writing a parser for
           every language that you want to interface with is a bit of an anti-pattern.

       This document consists of an API reference,  a  set  of  examples,  some  support  and  development  (for
       contributors)  information.  If you are new to Platypus or FFI, you may want to skip down to the EXAMPLES
       to get a taste of what you can do with Platypus.

       Platypus has extensive documentation of  types  at  FFI::Platypus::Type  and  its  custom  types  API  at
       FFI::Platypus::API.

       You  are strongly encouraged to use API level 1 for all new code.  There are a number of improvements and
       design fixes that you get for free.  You should even consider updating existing modules to use API  level
       1  where  feasible.   How  do  I  do  that  you  might ask?  Simply pass in the API level to the platypus
       constructor.

        my $ffi = FFI::Platypus->new( api => 1 );

       The Platypus documentation has already been updated to assume API level 1.

CONSTRUCTORS

   new
        my $ffi = FFI::Platypus->new( api => 1, %options);

       Create a new instance of FFI::Platypus.

       Any types defined with this instance will be valid for this instance only, so you do not  need  to  worry
       about stepping on the toes of other CPAN FFI / Platypus Authors.

       Any functions found will be out of the list of libraries specified with the lib attribute.

       options

       api Sets the API level.  Legal values are

           0   Original API level.  See FFI::Platypus::TypeParser::Version0 for details on the differences.

           1   Enable  the next generation type parser which allows pass-by-value records and type decoration on
               basic types.  Using API level 1 prior to Platypus version 1.00 will trigger a (noisy) warning.

               All new code should be written with this set to 1!  The Platypus documentation assumes  this  api
               level is set.

       lib Either  a  pathname  (string)  or  a list of pathnames (array ref of strings) to pre-populate the lib
           attribute.  Use "[undef]" to search the current process for symbols.

           0.48

           "undef" (without the array reference) can be used to search the current process for symbols.

       ignore_not_found
           [version 0.15]

           Set the ignore_not_found attribute.

       lang
           [version 0.18]

           Set the lang attribute.

ATTRIBUTES

   lib
        $ffi->lib($path1, $path2, ...);
        my @paths = $ffi->lib;

       The list of libraries to search for symbols in.

       The most portable and reliable way to find dynamic libraries is by using FFI::CheckLib, like this:

        use FFI::CheckLib 0.06;
        $ffi->lib(find_lib_or_die lib => 'archive');
          # finds libarchive.so on Linux
          #       libarchive.bundle on OS X
          #       libarchive.dll (or archive.dll) on Windows
          #       cygarchive-13.dll on Cygwin
          #       ...
          # and will die if it isn't found

       FFI::CheckLib has a number of options, such as checking for specific symbols, etc.   You  should  consult
       the documentation for that module.

       As  a  special  case,  if  you  add  "undef" as a "library" to be searched, Platypus will also search the
       current process for symbols. This is mostly useful for finding  functions  in  the  standard  C  library,
       without  having  to  know  the  name  of  the standard c library for your platform (as it turns out it is
       different just about everywhere!).

       You may also use the "find_lib" method as a shortcut:

        $ffi->find_lib( lib => 'archive' );

   ignore_not_found
       [version 0.15]

        $ffi->ignore_not_found(1);
        my $ignore_not_found = $ffi->ignore_not_found;

       Normally the attach and function methods will throw an exception if  it  cannot  find  the  name  of  the
       function  you  provide it.  This will change the behavior such that function will return "undef" when the
       function is not found and attach will ignore functions that are not found.  This is useful when  you  are
       writing  bindings to a library and have many optional functions and you do not wish to wrap every call to
       function or attach in an "eval".

   lang
       [version 0.18]

        $ffi->lang($language);

       Specifies the foreign language that you will be interfacing with. The default is C.  The foreign language
       specified with this attribute changes the default native types (for example, if  you  specify  Rust,  you
       will get "i32" as an alias for "sint32" instead of "int" as you do with C).

       If  the  foreign  language  plugin  supports it, this will also enable Platypus to find symbols using the
       demangled names (for example, if you specify CPP for C++ you can use method names  like  "Foo::get_bar()"
       with "attach" or "function".

METHODS

   type
        $ffi->type($typename);
        $ffi->type($typename => $alias);

       Define  a  type.  The first argument is the native or C name of the type.  The second argument (optional)
       is an alias name that you can use to refer to this new type.   See  FFI::Platypus::Type  for  legal  type
       definitions.

       Examples:

        $ffi->type('sint32');            # oly checks to see that sint32 is a valid type
        $ffi->type('sint32' => 'myint'); # creates an alias myint for sint32
        $ffi->type('bogus');             # dies with appropriate diagnostic

   custom_type
        $ffi->custom_type($alias => {
          native_type         => $native_type,
          native_to_perl      => $coderef,
          perl_to_native      => $coderef,
          perl_to_native_post => $coderef,
        });

       Define a custom type.  See FFI::Platypus::Type#Custom-Types for details.

   load_custom_type
        $ffi->load_custom_type($name => $alias, @type_args);

       Load  the  custom type defined in the module $name, and make an alias $alias. If the custom type requires
       any arguments, they may be passed in as @type_args. See FFI::Platypus::Type#Custom-Types for details.

       If $name contains "::" then it will be assumed to be  a  fully  qualified  package  name.  If  not,  then
       "FFI::Platypus::Type::" will be prepended to it.

   types
        my @types = $ffi->types;
        my @types = FFI::Platypus->types;

       Returns  the  list  of types that FFI knows about.  This will include the native "libffi" types (example:
       "sint32", "opaque" and "double") and the normal C types (example: "unsigned int", "uint32_t"), any  types
       that you have defined using the type method, and custom types.

       The   list   of   types   that   Platypus   knows  about  varies  somewhat  from  platform  to  platform,
       FFI::Platypus::Type includes a list of the core types that you can always count on having access to.

       It can also be called as a class method, in which case, no user defined or custom types will be  included
       in the list.

   type_meta
        my $meta = $ffi->type_meta($type_name);
        my $meta = FFI::Platypus->type_meta($type_name);

       Returns a hash reference with the meta information for the given type.

       It  can  also  be  called  as  a  class method, in which case, you won't be able to get meta data on user
       defined types.

       The format of the meta data is implementation dependent and subject to change.   It  may  be  useful  for
       display or debugging.

       Examples:

        my $meta = $ffi->type_meta('int');        # standard int type
        my $meta = $ffi->type_meta('int[64]');    # array of 64 ints
        $ffi->type('int[128]' => 'myintarray');
        my $meta = $ffi->type_meta('myintarray'); # array of 128 ints

   mangler
        $ffi->mangler(\&mangler);

       Specify  a  customer  mangler  to be used for symbol lookup.  This is usually useful when you are writing
       bindings for a library where all of the functions have the same prefix.  Example:

        $ffi->mangler(sub {
          my($symbol) = @_;
          return "foo_$symbol";
        });

        $ffi->function( get_bar => [] => 'int' );  # attaches foo_get_bar

        my $f = $ffi->function( set_baz => ['int'] => 'void' );
        $f->call(22); # calls foo_set_baz

   function
        my $function = $ffi->function($name => \@argument_types => $return_type);
        my $function = $ffi->function($address => \@argument_types => $return_type);
        my $function = $ffi->function($name => \@argument_types => $return_type, \&wrapper);
        my $function = $ffi->function($address => \@argument_types => $return_type, \&wrapper);

       Returns an object that is similar to a code reference in that it can be called like one.

       Caveat: many situations require a real code reference, so at the price of a performance penalty  you  can
       get one like this:

        my $function = $ffi->function(...);
        my $coderef = sub { $function->(@_) };

       It may be better, and faster to create a real Perl function using the attach method.

       In addition to looking up a function by name you can provide the address of the symbol yourself:

        my $address = $ffi->find_symbol('my_functon');
        my $function = $ffi->function($address => ...);

       Under  the  covers,  function  uses find_symbol when you provide it with a name, but it is useful to keep
       this in mind as there are alternative ways of obtaining a functions address.  Example: a C function could
       return the address of another C function that you might want to call,  or  modules  such  as  FFI::TinyCC
       produce machine code at runtime that you can call from Platypus.

       [version 0.76]

       If  the  last  argument  is  a code reference, then it will be used as a wrapper around the function when
       called.  The first argument to the wrapper will be the inner function, or if  it  is  later  attached  an
       xsub.  This can be used if you need to verify/modify input/output data.

       Examples:

        my $function = $ffi->function('my_function_name', ['int', 'string'] => 'string');
        my $return_string = $function->(1, "hi there");

       [version 0.91]

        my $function = $ffi->function( $name => \@fixed_argument_types => \@var_argument_types => $return_type);
        my $function = $ffi->function( $name => \@fixed_argument_types => \@var_argument_types => $return_type, \&wrapper);

       Version  0.91  and  later  allows you to creat functions for c variadic functions (such as printf, scanf,
       etc) which can take a variable number of arguments.  The first set of arguments are the  fixed  set,  the
       second  set  are  the  variable arguments to bind with.  The variable argument types must be specified in
       order to create a function object, so if you need  to  call  variadic  function  with  different  set  of
       arguments then you will need to create a new function object each time:

        # int printf(const char *fmt, ...);
        $ffi->function( printf => ['string'] => ['int'] => 'int' )
            ->call("print integer %d\n", 42);
        $ffi->function( printf => ['string'] => ['string'] => 'int' )
            ->call("print string %s\n", 'platypus');

       Some older versions of libffi and possibly some platforms may not support variadic functions.  If you try
       to create a one, then an exception will be thrown.

   attach
        $ffi->attach($name => \@argument_types => $return_type);
        $ffi->attach([$c_name => $perl_name] => \@argument_types => $return_type);
        $ffi->attach([$address => $perl_name] => \@argument_types => $return_type);
        $ffi->attach($name => \@argument_types => $return_type, \&wrapper);
        $ffi->attach([$c_name => $perl_name] => \@argument_types => $return_type, \&wrapper);
        $ffi->attach([$address => $perl_name] => \@argument_types => $return_type, \&wrapper);

       Find  and attach a C function as a real live Perl xsub.  The advantage of attaching a function over using
       the function method is that it is much much much faster since no object resolution needs to be done.  The
       disadvantage is that it locks the function and the FFI::Platypus instance into memory permanently,  since
       there is no way to deallocate an xsub.

       If just one $name is given, then the function will be attached in Perl with the same name as it has in C.
       The  second  form allows you to give the Perl function a different name.  You can also provide an address
       (the third form), just like with the function method.

       Examples:

        $ffi->attach('my_functon_name', ['int', 'string'] => 'string');
        $ffi->attach(['my_c_functon_name' => 'my_perl_function_name'], ['int', 'string'] => 'string');
        my $string1 = my_function_name($int);
        my $string2 = my_perl_function_name($int);

       [version 0.20]

       If the last argument is a code reference, then it will be used as a wrapper  around  the  attached  xsub.
       The  first argument to the wrapper will be the inner xsub.  This can be used if you need to verify/modify
       input/output data.

       Examples:

        $ffi->attach('my_function', ['int', 'string'] => 'string', sub {
          my($my_function_xsub, $integer, $string) = @_;
          $integer++;
          $string .= " and another thing";
          my $return_string = $my_function_xsub->($integer, $string);
          $return_string =~ s/Belgium//; # HHGG remove profanity
          $return_string;
        });

       [version 0.91]

        $ffi->attach($name => \@fixed_argument_types => \@var_argument_types, $return_type);
        $ffi->attach($name => \@fixed_argument_types => \@var_argument_types, $return_type, \&wrapper);

       As of version 0.91 you can attach a variadic functions, if it is supported by the platform / libffi  that
       you  are  using.   For  details see the "function" documentation.  If not supported by the implementation
       then an exception will be thrown.

   closure
        my $closure = $ffi->closure($coderef);
        my $closure = FFI::Platypus->closure($coderef);

       Prepares a code reference so that it can be used as a FFI closure (a Perl subroutine that can  be  called
       from C code).  For details on closures, see FFI::Platypus::Type#Closures and FFI::Platypus::Closure.

   cast
        my $converted_value = $ffi->cast($original_type, $converted_type, $original_value);

       The  "cast"  function  converts  an  existing  $original_value  of  type  $original_type into one of type
       $converted_type.  Not all types are supported, so care must be taken.  For example, to get the address of
       a string, you can do this:

        my $address = $ffi->cast('string' => 'opaque', $string_value);

       Something that won't work is trying to cast an array to anything:

        my $address = $ffi->cast('int[10]' => 'opaque', \@list);  # WRONG

   attach_cast
        $ffi->attach_cast("cast_name", $original_type, $converted_type);
        my $converted_value = cast_name($original_value);

       This function attaches a cast as a permanent xsub.  This will make it faster and may be useful if you are
       calling a particular cast a lot.

   sizeof
        my $size = $ffi->sizeof($type);
        my $size = FFI::Platypus->sizeof($type);

       Returns the total size of the given type in bytes.  For example to get the size of an integer:

        my $intsize = $ffi->sizeof('int');   # usually 4
        my $longsize = $ffi->sizeof('long'); # usually 4 or 8 depending on platform

       You can also get the size of arrays

        my $intarraysize = $ffi->sizeof('int[64]');  # usually 4*64
        my $intarraysize = $ffi->sizeof('long[64]'); # usually 4*64 or 8*64
                                                     # depending on platform

       Keep in mind that "pointer" types will always be the pointer / word size for the platform  that  you  are
       using.  This includes strings, opaque and pointers to other types.

       This  function  is not very fast, so you might want to save this value as a constant, particularly if you
       need the size in a loop with many iterations.

   alignof
       [version 0.21]

        my $align = $ffi->alignof($type);

       Returns the alignment of the given type in bytes.

   find_lib
       [version 0.20]

        $ffi->find_lib( lib => $libname );

       This  is  just  a  shortcut  for  calling  FFI::CheckLib#find_lib  and  updating  the   "lib"   attribute
       appropriately.    Care   should  be  taken  though,  as  this  method  simply  passes  its  arguments  to
       FFI::CheckLib#find_lib, so if your module or script is depending on a specific feature  in  FFI::CheckLib
       then make sure that you update your prerequisites appropriately.

   find_symbol
        my $address = $ffi->find_symbol($name);

       Return the address of the given symbol (usually function).

   bundle
       [version 0.96 api = 1+]

        $ffi->bundle($package, \@args);
        $ffi->bundle(\@args);
        $ffi->bundle($package);
        $ffi->bundle;

       This is an interface for bundling compiled code with your distribution intended to eventually replace the
       "package" method documented above.  See FFI::Platypus::Bundle for details on how this works.

   package
       [version 0.15 api = 0]

        $ffi->package($package, $file); # usually __PACKAGE__ and __FILE__ can be used
        $ffi->package;                  # autodetect

       Note: This method is officially discouraged in favor of "bundle" described above.

       If  you  use  FFI::Build  (or  the  older  deprecated  Module::Build::FFI  to  bundle  C  code  with your
       distribution, you can use this method to tell the FFI::Platypus instance to look for  symbols  that  came
       with the dynamic library that was built when your distribution was installed.

   abis
        my $href = $ffi->abis;
        my $href = FFI::Platypus->abis;

       Get  the legal ABIs supported by your platform and underlying implementation.  What is supported can vary
       a lot by CPU and by platform, or even between 32 and 64 bit on the same CPU and platform.  They keys  are
       the  "ABI"  names,  also  known as "calling conventions".  The values are integers used internally by the
       implementation to represent those ABIs.

   abi
        $ffi->abi($name);

       Set the ABI or calling convention for use in subsequent calls to "function" or "attach".  May be either a
       string name or integer value from the "abis" method above.

EXAMPLES

       Here are some examples.  These examples are provided in  full  with  the  Platypus  distribution  in  the
       "examples"  directory.   There  are  also  some  more examples in FFI::Platypus::Type that are related to
       types.

   Integer conversions
        use FFI::Platypus;

        my $ffi = FFI::Platypus->new( api => 1 );
        $ffi->lib(undef);

        $ffi->attach(puts => ['string'] => 'int');
        $ffi->attach(atoi => ['string'] => 'int');

        puts(atoi('56'));

       Discussion: "puts" and "atoi" should be part of the standard C library on all platforms.  "puts" prints a
       string to standard output, and "atoi" converts a string to integer.   Specifying  "undef"  as  a  library
       tells Platypus to search the current process for symbols, which includes the standard c library.

   libnotify
        use FFI::CheckLib;
        use FFI::Platypus;

        # NOTE: I ported this from anoter Perl FFI library and it seems to work most
        # of the time, but also seems to SIGSEGV sometimes.  I saw the same behavior
        # in the old version, and am not really familiar with the libnotify API to
        # say what is the cause.  Patches welcome to fix it.

        my $ffi = FFI::Platypus->new( api => 1 );
        $ffi->lib(find_lib_or_exit lib => 'notify');

        $ffi->attach(notify_init   => ['string'] => 'void');
        $ffi->attach(notify_uninit => []       => 'void');
        $ffi->attach([notify_notification_new    => 'notify_new']    => ['string', 'string', 'string']           => 'opaque');
        $ffi->attach([notify_notification_update => 'notify_update'] => ['opaque', 'string', 'string', 'string'] => 'void');
        $ffi->attach([notify_notification_show   => 'notify_show']   => ['opaque', 'opaque']                     => 'void');

        notify_init('FFI::Platypus');
        my $n = notify_new('','','');
        notify_update($n, 'FFI::Platypus', 'It works!!!', 'media-playback-start');
        notify_show($n, undef);
        notify_uninit();

       Discussion:  libnotify  is  a  desktop  GUI  notification library for the GNOME Desktop environment. This
       script sends a notification event that should show up as a balloon, for me it did so in the  upper  right
       hand corner of my screen.

       The  most  portable  way  to  find  the  correct  name  and  location  of  a  dynamic  library is via the
       FFI::CheckLib#find_lib family of functions.  If you are putting together a CPAN distribution, you  should
       also consider using FFI::CheckLib#check_lib_or_exit function in your "Build.PL" or "Makefile.PL" file (If
       you  are using Dist::Zilla, check out the Dist::Zilla::Plugin::FFI::CheckLib plugin). This will provide a
       user friendly diagnostic letting the user know that the required  library  is  missing,  and  reduce  the
       number of bogus CPAN testers results that you will get.

       Also  in  this  example,  we  rename  some  of the functions when they are placed into Perl space to save
       typing:

        $ffi->attach( [notify_notification_new => 'notify_new']
          => ['string','string','string']
          => 'opaque'
        );

       When you specify a list reference as the "name" of the function the first element is the symbol  name  as
       understood by the dynamic library.  The second element is the name as it will be placed in Perl space.

       Later, when we call "notify_new":

        my $n = notify_new('','','');

       We are really calling the C function "notify_notification_new".

   Allocating and freeing memory
        use FFI::Platypus;
        use FFI::Platypus::Memory qw( malloc free memcpy );

        my $ffi = FFI::Platypus->new( api => 1 );
        my $buffer = malloc 12;

        memcpy $buffer, $ffi->cast('string' => 'opaque', "hello there"), length "hello there\0";

        print $ffi->cast('opaque' => 'string', $buffer), "\n";

        free $buffer;

       Discussion:  "malloc"  and  "free" are standard memory allocation functions available from the standard c
       library  and.   Interfaces  to  these  and  other  memory  related  functions   are   provided   by   the
       FFI::Platypus::Memory module.

   structured data records
        package My::UnixTime;

        use FFI::Platypus::Record;

        record_layout_1(qw(
            int    tm_sec
            int    tm_min
            int    tm_hour
            int    tm_mday
            int    tm_mon
            int    tm_year
            int    tm_wday
            int    tm_yday
            int    tm_isdst
            long   tm_gmtoff
            string tm_zone
        ));

        my $ffi = FFI::Platypus->new( api => 1 );
        $ffi->lib(undef);
        # define a record class My::UnixTime and alias it to "tm"
        $ffi->type("record(My::UnixTime)*" => 'tm');

        # attach the C localtime function as a constructor
        $ffi->attach( localtime => ['time_t*'] => 'tm', sub {
          my($inner, $class, $time) = @_;
          $time = time unless defined $time;
          $inner->(\$time);
        });

        package main;

        # now we can actually use our My::UnixTime class
        my $time = My::UnixTime->localtime;
        printf "time is %d:%d:%d %s\n",
          $time->tm_hour,
          $time->tm_min,
          $time->tm_sec,
          $time->tm_zone;

       Discussion: C and other machine code languages frequently provide interfaces that include structured data
       records (known as "structs" in C).  They sometimes provide an API in which you are expected to manipulate
       these  records  before  and/or  after passing them along to C functions.  There are a few ways of dealing
       with such interfaces, but the easiest way is demonstrated here defines a record class  using  a  specific
       layout.   For  more  details see FFI::Platypus::Record.  (FFI::Platypus::Type includes some other ways of
       manipulating structured data records).

       The C "localtime" function takes a  pointer  to  a  record,  hence  we  suffix  the  type  with  a  star:
       "record(My::UnixTime)*".   If  the  function  takes  a  record  in  pass-by-value mode then we'd just say
       "record(My::UnixTime)" with no star suffix.

   libuuid
        use FFI::CheckLib;
        use FFI::Platypus;
        use FFI::Platypus::Memory qw( malloc free );

        my $ffi = FFI::Platypus->new( api => 1 );
        $ffi->lib(find_lib_or_exit lib => 'uuid');
        $ffi->type('string(37)*' => 'uuid_string');
        $ffi->type('record(16)*' => 'uuid_t');

        $ffi->attach(uuid_generate => ['uuid_t'] => 'void');
        $ffi->attach(uuid_unparse  => ['uuid_t','uuid_string'] => 'void');

        my $uuid = "\0" x 16;  # uuid_t
        uuid_generate($uuid);

        my $string = "\0" x 37; # 36 bytes to store a UUID string
                                # + NUL termination
        uuid_unparse($uuid, $string);

        print "$string\n";

       Discussion: libuuid is a library used to generate unique identifiers  (UUID)  for  objects  that  may  be
       accessible beyond the local system.  The library is or was part of the Linux e2fsprogs package.

       Knowing  the  size of objects is sometimes important.  In this example, we use the sizeof function to get
       the size of 16 characters (in this case it is simply 16 bytes).  We also know that the strings "deparsed"
       by "uuid_unparse" are exactly 37 bytes.

   puts and getpid
        use FFI::Platypus;

        my $ffi = FFI::Platypus->new( api => 1 );
        $ffi->lib(undef);

        $ffi->attach(puts => ['string'] => 'int');
        $ffi->attach(getpid => [] => 'int');

        puts(getpid());

       Discussion: "puts" is part of standard C library on all platforms.  "getpid" is available  on  Unix  type
       platforms.

   Math library
        use FFI::Platypus;
        use FFI::CheckLib;

        my $ffi = FFI::Platypus->new( api => 1 );
        $ffi->lib(undef);
        $ffi->attach(puts => ['string'] => 'int');
        $ffi->attach(fdim => ['double','double'] => 'double');

        puts(fdim(7.0, 2.0));

        $ffi->attach(cos => ['double'] => 'double');

        puts(cos(2.0));

        $ffi->attach(fmax => ['double', 'double'] => 'double');

        puts(fmax(2.0,3.0));

       Discussion:  On  UNIX the standard c library math functions are frequently provided in a separate library
       "libm", so you could search for those symbols in "libm.so", but that won't  work  on  non-UNIX  platforms
       like  Microsoft  Windows.   Fortunately  Perl  uses  the math library so these symbols are already in the
       current process so you can use "undef" as the library to find them.

   Strings
        use FFI::Platypus;

        my $ffi = FFI::Platypus->new;
        $ffi->lib(undef);
        $ffi->attach(puts => ['string'] => 'int');
        $ffi->attach(strlen => ['string'] => 'int');

        puts(strlen('somestring'));

        $ffi->attach(strstr => ['string','string'] => 'string');

        puts(strstr('somestring', 'string'));

        #attach puts => [string] => int;

        puts(puts("lol"));

        $ffi->attach(strerror => ['int'] => 'string');

        puts(strerror(2));

       Discussion: Strings are not a native type to "libffi" but the are handled seamlessly by Platypus.

   Attach function from pointer
        use FFI::TinyCC;
        use FFI::Platypus;

        my $ffi = FFI::Platypus->new( api => 1 );
        my $tcc = FFI::TinyCC->new;

        $tcc->compile_string(q{
          int
          add(int a, int b)
          {
            return a+b;
          }
        });

        my $address = $tcc->get_symbol('add');

        $ffi->attach( [ $address => 'add' ] => ['int','int'] => 'int' );

        print add(1,2), "\n";

       Discussion: Sometimes you will have a pointer to a function from a source other than  Platypus  that  you
       want  to  call.  You can use that address instead of a function name for either of the function or attach
       methods.  In this example we use FFI::TinyCC to compile a short piece of  C  code  and  to  give  us  the
       address of one of its functions, which we then use to create a perl xsub to call it.

       FFI::TinyCC embeds the Tiny C Compiler (tcc) to provide a just-in-time (JIT) compilation service for FFI.

   libzmq
        use constant ZMQ_IO_THREADS  => 1;
        use constant ZMQ_MAX_SOCKETS => 2;
        use constant ZMQ_REQ => 3;
        use constant ZMQ_REP => 4;
        use FFI::CheckLib qw( find_lib_or_exit );
        use FFI::Platypus;
        use FFI::Platypus::Memory qw( malloc );
        use FFI::Platypus::Buffer qw( scalar_to_buffer buffer_to_scalar );

        my $endpoint = "ipc://zmq-ffi-$$";
        my $ffi = FFI::Platypus->new( api => 1 );

        $ffi->lib(undef); # for puts
        $ffi->attach(puts => ['string'] => 'int');

        $ffi->lib(find_lib_or_exit lib => 'zmq');
        $ffi->attach(zmq_version => ['int*', 'int*', 'int*'] => 'void');

        my($major,$minor,$patch);
        zmq_version(\$major, \$minor, \$patch);
        puts("libzmq version $major.$minor.$patch");
        die "this script only works with libzmq 3 or better" unless $major >= 3;

        $ffi->type('opaque'       => 'zmq_context');
        $ffi->type('opaque'       => 'zmq_socket');
        $ffi->type('opaque'       => 'zmq_msg_t');
        $ffi->attach(zmq_ctx_new  => [] => 'zmq_context');
        $ffi->attach(zmq_ctx_set  => ['zmq_context', 'int', 'int'] => 'int');
        $ffi->attach(zmq_socket   => ['zmq_context', 'int'] => 'zmq_socket');
        $ffi->attach(zmq_connect  => ['opaque', 'string'] => 'int');
        $ffi->attach(zmq_bind     => ['zmq_socket', 'string'] => 'int');
        $ffi->attach(zmq_send     => ['zmq_socket', 'opaque', 'size_t', 'int'] => 'int');
        $ffi->attach(zmq_msg_init => ['zmq_msg_t'] => 'int');
        $ffi->attach(zmq_msg_recv => ['zmq_msg_t', 'zmq_socket', 'int'] => 'int');
        $ffi->attach(zmq_msg_data => ['zmq_msg_t'] => 'opaque');
        $ffi->attach(zmq_errno    => [] => 'int');
        $ffi->attach(zmq_strerror => ['int'] => 'string');

        my $context = zmq_ctx_new();
        zmq_ctx_set($context, ZMQ_IO_THREADS, 1);

        my $socket1 = zmq_socket($context, ZMQ_REQ);
        zmq_connect($socket1, $endpoint);

        my $socket2 = zmq_socket($context, ZMQ_REP);
        zmq_bind($socket2, $endpoint);

        do { # send
          our $sent_message = "hello there";
          my($pointer, $size) = scalar_to_buffer $sent_message;
          my $r = zmq_send($socket1, $pointer, $size, 0);
          die zmq_strerror(zmq_errno()) if $r == -1;
        };

        do { # recv
          my $msg_ptr  = malloc 100;
          zmq_msg_init($msg_ptr);
          my $size     = zmq_msg_recv($msg_ptr, $socket2, 0);
          die zmq_strerror(zmq_errno()) if $size == -1;
          my $data_ptr = zmq_msg_data($msg_ptr);
          my $recv_message = buffer_to_scalar $data_ptr, $size;
          print "recv_message = $recv_message\n";
        };

       Discussion:  ØMQ  is  a  high-performance asynchronous messaging library.  There are a few things to note
       here.

       Firstly, sometimes there may be multiple versions of a library in the wild and you  may  need  to  verify
       that  the  library  on  a  system meets your needs (alternatively you could support multiple versions and
       configure your bindings dynamically).  Here we use "zmq_version" to ask libzmq which version it is.

       "zmq_version" returns the version number via three integer pointer arguments, so we use  the  pointer  to
       integer  type:  "int  *".   In  order  to  pass  pointer types, we pass a reference. In this case it is a
       reference to an undefined value, because zmq_version will write into the pointers the output values,  but
       you  can  also  pass in references to integers, floating point values and opaque pointer types.  When the
       function returns the $major variable (and the others) has been updated and we can use it to  verify  that
       it supports the API that we require.

       Notice  that  we define three aliases for the "opaque" type: "zmq_context", "zmq_socket" and "zmq_msg_t".
       While this isn't strictly necessary, since Platypus and C treat all three of these types the same, it  is
       useful form of documentation that helps describe the functionality of the interface.

       Finally we attach the necessary functions, send and receive a message.  If you are interested, there is a
       fully fleshed out ØMQ Perl interface implemented using FFI called ZMQ::FFI.

   libarchive
        use FFI::Platypus      ();
        use FFI::CheckLib      qw( find_lib_or_exit );

        # This example uses FreeBSD's libarchive to list the contents of any
        # archive format that it suppors.  We've also filled out a part of
        # the ArchiveWrite class that could be used for writing archive formats
        # supported by libarchive

        my $ffi = FFI::Platypus->new( api => 1 );
        $ffi->lib(find_lib_or_exit lib => 'archive');
        $ffi->type('object(Archive)'      => 'archive_t');
        $ffi->type('object(ArchiveRead)'  => 'archive_read_t');
        $ffi->type('object(ArchiveWrite)' => 'archive_write_t');
        $ffi->type('object(ArchiveEntry)' => 'archive_entry_t');

        package Archive;

        # base class is "abstract" having no constructor or destructor

        $ffi->mangler(sub {
          my($name) = @_;
          "archive_$name";
        });
        $ffi->attach( error_string => ['archive_t'] => 'string' );

        package ArchiveRead;

        our @ISA = qw( Archive );

        $ffi->mangler(sub {
          my($name) = @_;
          "archive_read_$name";
        });

        $ffi->attach( new                   => ['string']                        => 'archive_read_t' );
        $ffi->attach( [ free => 'DESTROY' ] => ['archive_t']                     => 'void' );
        $ffi->attach( support_filter_all    => ['archive_t']                     => 'int' );
        $ffi->attach( support_format_all    => ['archive_t']                     => 'int' );
        $ffi->attach( open_filename         => ['archive_t','string','size_t']   => 'int' );
        $ffi->attach( next_header2          => ['archive_t', 'archive_entry_t' ] => 'int' );
        $ffi->attach( data_skip             => ['archive_t']                     => 'int' );
        # ... define additional read methods

        package ArchiveWrite;

        our @ISA = qw( Archive );

        $ffi->mangler(sub {
          my($name) = @_;
          "archive_write_$name";
        });

        $ffi->attach( new                   => ['string'] => 'archive_write_t' );
        $ffi->attach( [ free => 'DESTROY' ] => ['archive_write_t'] => 'void' );
        # ... define additional write methods

        package ArchiveEntry;

        $ffi->mangler(sub {
          my($name) = @_;
          "archive_entry_$name";
        });

        $ffi->attach( new => ['string']     => 'archive_entry_t' );
        $ffi->attach( [ free => 'DESTROY' ] => ['archive_entry_t'] => 'void' );
        $ffi->attach( pathname              => ['archive_entry_t'] => 'string' );
        # ... define additional entry methods

        package main;

        use constant ARCHIVE_OK => 0;

        # this is a Perl version of the C code here:
        # https://github.com/libarchive/libarchive/wiki/Examples#List_contents_of_Archive_stored_in_File

        my $archive_filename = shift @ARGV;
        unless(defined $archive_filename)
        {
          print "usage: $0 archive.tar\n";
          exit;
        }

        my $archive = ArchiveRead->new;
        $archive->support_filter_all;
        $archive->support_format_all;

        my $r = $archive->open_filename($archive_filename, 1024);
        die "error opening $archive_filename: ", $archive->error_string
          unless $r == ARCHIVE_OK;

        my $entry = ArchiveEntry->new;

        while($archive->next_header2($entry) == ARCHIVE_OK)
        {
          print $entry->pathname, "\n";
          $archive->data_skip;
        }

       Discussion:  libarchive is the implementation of "tar" for FreeBSD provided as a library and available on
       a number of platforms.

       One interesting thing about libarchive is that it provides a kind of object oriented interface via opaque
       pointers.  This example creates  an  abstract  class  "Archive",  and  concrete  classes  "ArchiveWrite",
       "ArchiveRead" and "ArchiveEntry".  The concrete classes can even be inherited from and extended just like
       any  Perl  classes  because of the way the custom types are implemented.  We use Platypus's "object" type
       for this implementation, which is a wrapper around an "opaque" (can also be  an  integer)  type  that  is
       blessed into a particular class.

       Another  advanced feature of this example is that we define a mangler to modify the symbol resolution for
       each class.  This means we can do this when we define a method for Archive:

        $ffi->attach( support_filter_all => ['archive_t'] => 'int' );

       Rather than this:

        $ffi->attach(
          [ archive_read_support_filter_all => 'support_read_filter_all' ] =>
          ['archive_t'] => 'int' );
        );

   unix open
        use FFI::Platypus;

        {
          package FD;

          use constant O_RDONLY => 0;
          use constant O_WRONLY => 1;
          use constant O_RDWR   => 2;

          use constant IN  => bless \do { my $in=0  }, __PACKAGE__;
          use constant OUT => bless \do { my $out=1 }, __PACKAGE__;
          use constant ERR => bless \do { my $err=2 }, __PACKAGE__;

          my $ffi = FFI::Platypus->new( api => 1, lib => [undef]);

          $ffi->type('object(FD,int)' => 'fd');

          $ffi->attach( [ 'open' => 'new' ] => [ 'string', 'int', 'mode_t' ] => 'fd' => sub {
            my($xsub, $class, $fn, @rest) = @_;
            my $fd = $xsub->($fn, @rest);
            die "error opening $fn $!" if $$fd == -1;
            $fd;
          });

          $ffi->attach( write => ['fd', 'string', 'size_t' ] => 'ssize_t' );
          $ffi->attach( read  => ['fd', 'string', 'size_t' ] => 'ssize_t' );
          $ffi->attach( close => ['fd'] => 'int' );
        }

        my $fd = FD->new("$0", FD::O_RDONLY);

        my $buffer = "\0" x 10;

        while(my $br = $fd->read($buffer, 10))
        {
          FD::OUT->write($buffer, $br);
        }

        $fd->close;

       Discussion: The Unix file system calls use an integer handle for each open file.  We  can  use  the  same
       "object"  type that we used for libarchive above, except we let platypus know that the underlying type is
       "int" instead of "opaque" (the latter being  the  default  for  the  "object"  type).   Mainly  just  for
       demonstration  since  Perl  has  much better IO libraries, but now we have an OO interface to the Unix IO
       functions.

   bzip2
        use FFI::Platypus 0.20 (); # 0.20 required for using wrappers
        use FFI::CheckLib qw( find_lib_or_die );
        use FFI::Platypus::Buffer qw( scalar_to_buffer buffer_to_scalar );
        use FFI::Platypus::Memory qw( malloc free );

        my $ffi = FFI::Platypus->new( api => 1 );
        $ffi->lib(find_lib_or_die lib => 'bz2');

        $ffi->attach(
          [ BZ2_bzBuffToBuffCompress => 'compress' ] => [
            'opaque',                           # dest
            'unsigned int *',                   # dest length
            'opaque',                           # source
            'unsigned int',                     # source length
            'int',                              # blockSize100k
            'int',                              # verbosity
            'int',                              # workFactor
          ] => 'int',
          sub {
            my $sub = shift;
            my($source,$source_length) = scalar_to_buffer $_[0];
            my $dest_length = int(length($source)*1.01) + 1 + 600;
            my $dest = malloc $dest_length;
            my $r = $sub->($dest, \$dest_length, $source, $source_length, 9, 0, 30);
            die "bzip2 error $r" unless $r == 0;
            my $compressed = buffer_to_scalar($dest, $dest_length);
            free $dest;
            $compressed;
          },
        );

        $ffi->attach(
          [ BZ2_bzBuffToBuffDecompress => 'decompress' ] => [
            'opaque',                           # dest
            'unsigned int *',                   # dest length
            'opaque',                           # source
            'unsigned int',                     # source length
            'int',                              # small
            'int',                              # verbosity
          ] => 'int',
          sub {
            my $sub = shift;
            my($source, $source_length) = scalar_to_buffer $_[0];
            my $dest_length = $_[1];
            my $dest = malloc $dest_length;
            my $r = $sub->($dest, \$dest_length, $source, $source_length, 0, 0);
            die "bzip2 error $r" unless $r == 0;
            my $decompressed = buffer_to_scalar($dest, $dest_length);
            free $dest;
            $decompressed;
          },
        );

        my $original = "hello compression world\n";
        my $compressed = compress($original);
        print decompress($compressed, length $original);

       Discussion: bzip2 is a compression library.  For simple one shot  attempts  at  compression/decompression
       when  you  expect  the original and the result to fit within memory it provides two convenience functions
       "BZ2_bzBuffToBuffCompress" and "BZ2_bzBuffToBuffDecompress".

       The first four arguments of both of these C functions are identical,  and  represent  two  buffers.   One
       buffer  is  the source, the second is the destination.  For the destination, the length is passed in as a
       pointer to an integer.  On input this integer is the size of the destination buffer, and thus the maximum
       size of the compressed or decompressed data.  When the function returns the actual size of compressed  or
       compressed data is stored in this integer.

       This is normal stuff for C, but in Perl our buffers are scalars and they already know how large they are.
       In  this  sort  of  situation, wrapping the C function in some Perl code can make your interface a little
       more Perl like.  In order to do this, just provide a code reference as the last argument to the  "attach"
       method.   The  first  argument  to  this  wrapper  will  be a code reference to the C function.  The Perl
       arguments will come in after that.  This allows you to modify / convert the arguments to conform to the C
       API.  What ever value you return from the wrapper function will be returned back to the original caller.

   bundle your own code
       "ffi/foo.c":

        #include <ffi_platypus_bundle.h>
        #include <string.h>

        typedef struct {
          char *name;
          int value;
        } foo_t;

        foo_t*
        foo__new(const char *class_name, const char *name, int value)
        {
          (void)class_name;
          foo_t *self = malloc( sizeof( foo_t ) );
          self->name = strdup(name);
          self->value = value;
          return self;
        }

        const char *
        foo__name(foo_t *self)
        {
          return self->name;
        }

        int
        foo__value(foo_t *self)
        {
          return self->value;
        }

        void
        foo__DESTROY(foo_t *self)
        {
          free(self->name);
          free(self);
        }

       "lib/Foo.pm":

        package Foo;

        use strict;
        use warnings;
        use FFI::Platypus;

        {
          my $ffi = FFI::Platypus->new( api => 1 );

          $ffi->type('object(Foo)' => 'foo_t');
          $ffi->mangler(sub {
            my $name = shift;
            $name =~ s/^/foo__/;
            $name;
          });

          $ffi->bundle;

          $ffi->attach( new =>     [ 'string', 'string', 'int' ] => 'foo_t'  );
          $ffi->attach( name =>    [ 'foo_t' ]                   => 'string' );
          $ffi->attach( value =>   [ 'foo_t' ]                   => 'int'    );
          $ffi->attach( DESTROY => [ 'foo_t' ]                   => 'void'   );
        }

        1;

       You can bundle your own C (or other compiled language) code with your Perl extension.  Sometimes this  is
       helpful  for  smoothing  over the interface of a C library which is not very FFI friendly.  Sometimes you
       may want to write some code in C for a tight loop.  Either way, you can do this with the Platypus  bundle
       interface.  See FFI::Platypus::Bundle for more details.

       Also related is the bundle constant interface, which allows you to define Perl constants in C space.  See
       FFI::Platypus::Constant for details.

FAQ

   How do I get constants defined as macros in C header files
       This  turns out to be a challenge for any language calling into C, which frequently uses "#define" macros
       to define constants like so:

        #define FOO_STATIC  1
        #define FOO_DYNAMIC 2
        #define FOO_OTHER   3

       As macros are expanded and their definitions are thrown away by the C pre-processor there isn't  any  way
       to get the name/value mappings from the compiled dynamic library.

       You can manually create equivalent constants in your Perl source:

        use constant FOO_STATIC  => 1;
        use constant FOO_DYNAMIC => 2;
        use constant FOO_OTHER   => 3;

       If   there   are  a  lot  of  these  types  of  constants  you  might  want  to  consider  using  a  tool
       (Convert::Binary::C can do this) that can extract the constants for you.

       See also the "Integer constants" example in FFI::Platypus::Type.

       You can also use the new Platypus bundle interface to define Perl constants from C space.  This  is  more
       reliable,  but  does  require  a compiler at install time.  It is recommended mainly for writing bindings
       against  libraries  that  have  constants  that  can  vary  widely  from  platform  to   platform.    See
       FFI::Platypus::Constant for details.

   What about enums?
       The  C  enum  types are integers.  The underlying type is up to the platform, so Platypus provides "enum"
       and "senum" types for unsigned and singed enums respectively.  At least some compilers treat  signed  and
       unsigned enums as different types.  The enum values are essentially the same as macro constants described
       above  from  an FFI perspective.  Thus the process of defining enum values is identical to the process of
       defining macro constants in Perl.

       For more details on enumerated types see "Enum types" in FFI::Platypus::Type.

   Memory leaks
       There are a couple places where memory is allocated, but never deallocated  that  may  look  like  memory
       leaks  by  tools designed to find memory leaks like valgrind.  This memory is intended to be used for the
       lifetime of the perl process so there normally this isn't a problem  unless  you  are  embedding  a  Perl
       interpreter which doesn't closely match the lifetime of your overall application.

       Specifically:

       type cache
           some  types are cached and not freed.  These are needed as long as there are FFI functions that could
           be called.

       attached functions
           Attaching a function as an xsub will definitely allocate memory that won't be freed because the  xsub
           could be called at any time, including in "END" blocks.

       The  Platypus  team  plans on adding a hook to free some of this "leaked" memory for use cases where Perl
       and Platypus are embedded in a larger application where the lifetime of the Perl process is significantly
       smaller than the overall lifetime of the whole process.

   I get seg faults on some platforms but not others with a library using pthreads.
       On some platforms, Perl isn't linked with "libpthreads"  if  Perl  threads  are  not  enabled.   On  some
       platforms  this  doesn't  seem to matter, "libpthreads" can be loaded at runtime without much ill-effect.
       (Linux from my experience doesn't seem to mind one way or the other).  Some platforms are not happy about
       this, and about the only thing that you can do about it  is  to  build  Perl  such  that  it  links  with
       "libpthreads" even if it isn't a threaded Perl.

       This  is not really an FFI issue, but a Perl issue, as you will have the same problem writing XS code for
       the such libraries.

   Doesn't work on Perl 5.10.0.
       I try as best as possible to support the same range of Perls as the Perl toolchain.  That means  all  the
       way back to 5.8.1.  Unfortunately, 5.10.0 seems to have a problem that is difficult to diagnose.  Patches
       to fix are welcome, if you want to help out on this, please see:

       <https://github.com/Perl5-FFI/FFI-Platypus/issues/68>

       Since  this  is  an  older  buggy version of Perl it is recommended that you instead upgrade to 5.10.1 or
       later.

CAVEATS

       Platypus and Native Interfaces like libffi rely on the availability of  dynamic  libraries.   Things  not
       supported include:

       Systems that lack dynamic library support
           Like MS-DOS

       Systems that are not supported by libffi
           Like OpenVMS

       Languages that do not support using dynamic libraries from other languages
           Like older versions of Google's Go. This is a problem for C / XS code as well.

       Languages that do not compile to machine code
           Like .NET based languages and Java.

       The  documentation  has a bias toward using FFI / Platypus with C.  This is my fault, as my background in
       mainly in C/C++ programmer (when I am not writing Perl).  In many places I use "C" as a  short  form  for
       "any  language  that  can  generate machine code and is callable from C".  I welcome pull requests to the
       Platypus core to address this issue.  In an attempt to ease usage of Platypus by  non  C  programmers,  I
       have written a number of foreign language plugins for various popular languages (see the SEE ALSO below).
       These  plugins come with examples specific to those languages, and documentation on common issues related
       to using those languages with FFI.  In most cases these are available for easy adoption  for  those  with
       the  know-how  or  the  willingness  to  learn.  If your language doesn't have a plugin YET, that is just
       because you haven't written it yet.

SUPPORT

       IRC: #native on irc.perl.org

       (click for instant chat room login) <http://chat.mibbit.com/#native@irc.perl.org>

       If something does not work the way you think it should, or if you have a feature request, please open  an
       issue on this project's GitHub Issue tracker:

       <https://github.com/perl5-FFI/FFI-Platypus/issues>

CONTRIBUTING

       If  you  have implemented a new feature or fixed a bug then you may make a pull request on this project's
       GitHub repository:

       <https://github.com/Perl5-FFI/FFI-Platypus/pulls>

       This project is  developed  using  Dist::Zilla.   The  project's  git  repository  also  comes  with  the
       "Makefile.PL"   file  necessary  for  building,  testing  (and  even  installing  if  necessary)  without
       Dist::Zilla.  Please keep in mind though that these files are generated so if changes need to be made  to
       those  files  they  should  be done through the project's "dist.ini" file.  If you do use Dist::Zilla and
       already have the necessary plugins installed, then I encourage you to run "dzil test" before  making  any
       pull  requests.   This  is not a requirement, however, I am happy to integrate especially smaller patches
       that need tweaking to fit the project standards.  I may push back and ask you to write  a  test  case  or
       alter  the  formatting of a patch depending on the amount of time I have and the amount of code that your
       patch touches.

       This project's GitHub issue tracker listed above is not Write-Only.  If you want to contribute then  feel
       free  to  browse  through the existing issues and see if there is something you feel you might be good at
       and take a whack at the problem.  I frequently open issues myself that I hope  will  be  accomplished  by
       someone in the future but do not have time to immediately implement myself.

       Another  good  area  to  help  out  in  is documentation.  I try to make sure that there is good document
       coverage, that is there should be documentation describing all the public  features  and  warnings  about
       common  pitfalls,  but  an outsider's or alternate view point on such things would be welcome; if you see
       something confusing or lacks sufficient detail I encourage documentation only pull  requests  to  improve
       things.

       The  Platypus distribution comes with a test library named "libtest" that is normally automatically built
       by "./Build test".  If you prefer to use "prove" or run tests directly, you can use the "./Build libtest"
       command to build it.  Example:

        % perl Makefile.PL
        % make
        % make ffi-test
        % prove -bv t
        # or an individual test
        % perl -Mblib t/ffi_platypus_memory.t

       The build process also respects these environment variables:

       FFI_PLATYPUS_DEBUG_FAKE32
           When building Platypus on 32 bit Perls, it will use the Math::Int64 C  API  and  make  Math::Int64  a
           prerequisite.   Setting  this  environment  variable  will force Platypus to build with both of those
           options on a 64 bit Perl as well.

            % env FFI_PLATYPUS_DEBUG_FAKE32=1 perl Makefile.PL
            DEBUG_FAKE32:
              + making Math::Int64 a prereq
              + Using Math::Int64's C API to manipulate 64 bit values
            Generating a Unix-style Makefile
            Writing Makefile for FFI::Platypus
            Writing MYMETA.yml and MYMETA.json
            %

       FFI_PLATYPUS_NO_ALLOCA
           Platypus uses the non-standard and somewhat controversial C function "alloca" by default on platforms
           that support it.  I believe that Platypus uses it responsibly to allocate small amounts of memory for
           argument type parameters, and does not use it to allocate large structures like  arrays  or  buffers.
           If you prefer not to use "alloca" despite these precautions, then you can turn its use off by setting
           this environment variable when you run "Makefile.PL":

            helix% env FFI_PLATYPUS_NO_ALLOCA=1 perl Makefile.PL
            NO_ALLOCA:
              + alloca() will not be used, even if your platform supports it.
            Generating a Unix-style Makefile
            Writing Makefile for FFI::Platypus
            Writing MYMETA.yml and MYMETA.json

       V   When  building  platypus  may hide some of the excessive output when probing and building, unless you
           set "V" to a true value.

            % env V=1 perl Makefile.PL
            % make V=1
            ...

   Coding Guidelines
       •   Do not hesitate to make code contribution.   Making  useful  contributions  is  more  important  than
           following byzantine bureaucratic coding regulations.  We can always tweak things later.

       •   Please make an effort to follow existing coding style when making pull requests.

       •   Platypus supports all production Perl releases since 5.8.1.  For that reason, please do not introduce
           any code that requires a newer version of Perl.

   Performance Testing
       As  Mark  Twain  was  fond  of  saying  there  are  four  types  of lies: lies, damn lies, statistics and
       benchmarks.  That being said, it can sometimes be helpful to compare the runtime performance of  Platypus
       if  you are making significant changes to the Platypus Core.  For that I use `FFI-Performance`, which can
       be found in my GitHub repository here:

       <https://github.com/Perl5-FFI/FFI-Performance>

   System integrators
       This distribution uses Alien::FFI in fallback mode, meaning if the system  doesn't  provide  "pkg-config"
       and  "libffi"  it  will  attempt  to  download  "libffi"  and build it from source.  If you are including
       Platypus in a larger system (for example a Linux distribution) you only need  to  make  sure  to  declare
       "pkg-config" or "pkgconf" and the development package for "libffi" as prereqs for this module.

SEE ALSO

       NativeCall
           Promising interface to Platypus inspired by Perl 6.

       FFI::Platypus::Type
           Type definitions for Platypus.

       FFI::Platypus::Record
           Define structured data records (C "structs") for use with Platypus.

       FFI::Platypus::API
           The custom types API for Platypus.

       FFI::Platypus::Memory
           Memory functions for FFI.

       FFI::CheckLib
           Find dynamic libraries in a portable way.

       FFI::TinyCC
           JIT compiler for FFI.

       FFI::Platypus::Lang::C
           Documentation and tools for using Platypus with the C programming language

       FFI::Platypus::Lang::CPP
           Documentation and tools for using Platypus with the C++ programming language

       FFI::Platypus::Lang::Fortran
           Documentation and tools for using Platypus with Fortran

       FFI::Platypus::Lang::Pascal
           Documentation and tools for using Platypus with Free Pascal

       FFI::Platypus::Lang::Rust
           Documentation and tools for using Platypus with the Rust programming language

       FFI::Platypus::Lang::ASM
           Documentation and tools for using Platypus with the Assembly

       Convert::Binary::C
           A great interface for decoding C data structures, including "struct"s, "enum"s, "#define"s and more.

       pack and unpack
           Native to Perl functions that can be used to decode C "struct" types.

       C::Scan
           This  module  can extract constants and other useful objects from C header files that may be relevant
           to an FFI application.  One downside  is  that  its  use  may  require  development  packages  to  be
           installed.

       Win32::API
           Microsoft Windows specific FFI style interface.

       Ctypes <https://gitorious.org/perl-ctypes>
           Ctypes  was  intended as a FFI style interface for Perl, but was never part of CPAN, and at least the
           last time I tried it did not work with recent versions of Perl.

       FFI Foreign function interface based on (nomenclature is everything) FSF's "ffcall". It hasn't worked for
           quite some time, and "ffcall" is no longer supported or distributed.

       C::DynaLib
           Another FFI for Perl that doesn't appear to have worked for a long time.

       C::Blocks
           Embed a tiny C compiler into your Perl scripts.

       Alien::FFI
           Provides libffi for Platypus during its configuration and build stages.

       P5NCI
           Yet another FFI like interface that does not appear to be supported or under development anymore.

ACKNOWLEDGMENTS

       In addition to the contributors mentioned below, I would like to acknowledge Brock Wilcox  (AWWAIID)  and
       Meredith  Howard  (MHOWARD)  whose  work  on  "FFI::Sweet"  not  only  helped me get started with FFI but
       significantly influenced the design of Platypus.

       Dan Book, who goes by Grinnz on IRC for answering user questions about FFI and Platypus.

       In addition I'd like to thank Alessandro Ghedini (ALEXBIO) whose work on another Perl FFI library  helped
       drive some of the development ideas for FFI::Platypus.

AUTHOR

       Author: Graham Ollis <plicease@cpan.org>

       Contributors:

       Bakkiaraj Murugesan (bakkiaraj)

       Dylan Cali (calid)

       pipcet

       Zaki Mughal (zmughal)

       Fitz Elliott (felliott)

       Vickenty Fesunov (vyf)

       Gregor Herrmann (gregoa)

       Shlomi Fish (shlomif)

       Damyan Ivanov

       Ilya Pavlov (Ilya33)

       Petr Pisar (ppisar)

       Mohammad S Anwar (MANWAR)

       Håkon Hægland (hakonhagland, HAKONH)

       Meredith (merrilymeredith, MHOWARD)

       Diab Jerius (DJERIUS)

COPYRIGHT AND LICENSE

       This software is copyright (c) 2015,2016,2017,2018,2019 by Graham Ollis.

       This  is  free  software;  you  can  redistribute  it and/or modify it under the same terms as the Perl 5
       programming language system itself.

perl v5.30.0                                       2020-02-09                                 FFI::Platypus(3pm)