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NEED_function NEED_function_GLOBAL NEED_variable NEED_variable_GLOBAL DPPP_NAMESPACE


ppport.h - Perl/Pollution/Portability version __VERSION__


  perl ppport.h [options] [source files]

  Searches current directory for files if no [source files] are given

  --help                      show short help

  --version                   show version

  --patch=file                write one patch file with changes
  --copy=suffix               write changed copies with suffix
  --diff=program              use diff program and options

  --compat-version=version    provide compatibility with Perl version
  --cplusplus                 accept C++ comments

  --quiet                     don't output anything except fatal errors
  --nodiag                    don't show diagnostics
  --nohints                   don't show hints
  --nochanges                 don't suggest changes
  --nofilter                  don't filter input files

  --strip                     strip all script and doc functionality
                              from ppport.h

  --list-provided             list provided API
  --list-unsupported          list API that isn't supported all the way
  --api-info=name             show Perl API portability information


This version of ppport.h is designed to support operation with Perl installations back to __MIN_PERL__, and has been tested up to __MAX_PERL__.



Display a brief usage summary.


Display the version of ppport.h.


If this option is given, a single patch file will be created if any changes are suggested. This requires a working diff program to be installed on your system.


If this option is given, a copy of each file will be saved with the given suffix that contains the suggested changes. This does not require any external programs. Note that this does not automagically add a dot between the original filename and the suffix. If you want the dot, you have to include it in the option argument.

If neither --patch or --copy are given, the default is to simply print the diffs for each file. This requires either Text::Diff or a diff program to be installed.


Manually set the diff program and options to use. The default is to use Text::Diff, when installed, and output unified context diffs.


Tell ppport.h to check for compatibility with the given Perl version. The default is to check for compatibility with Perl version __MIN_PERL__. You can use this option to reduce the output of ppport.h if you intend to be backward compatible only down to a certain Perl version.


Usually, ppport.h will detect C++ style comments and replace them with C style comments for portability reasons. Using this option instructs ppport.h to leave C++ comments untouched.


Be quiet. Don't print anything except fatal errors.


Don't output any diagnostic messages. Only portability alerts will be printed.


Don't output any hints. Hints often contain useful portability notes. Warnings will still be displayed.


Don't suggest any changes. Only give diagnostic output and hints unless these are also deactivated.


Don't filter the list of input files. By default, files not looking like source code (i.e. not *.xs, *.c, *.cc, *.cpp or *.h) are skipped.


Strip all script and documentation functionality from ppport.h. This reduces the size of ppport.h dramatically and may be useful if you want to include ppport.h in smaller modules without increasing their distribution size too much.

The stripped ppport.h will have a --unstrip option that allows you to undo the stripping, but only if an appropriate Devel::PPPort module is installed.


Lists the API elements for which compatibility is provided by ppport.h. Also lists if it must be explicitly requested, if it has dependencies, and if there are hints or warnings for it.


Lists the API elements that are known not to be FULLY supported by ppport.h, and below which version of Perl they probably won't be available or work. By FULLY, we mean that support isn't provided all the way back to the first version of Perl that ppport.h supports at all.


Show portability information for elements matching name. If name is surrounded by slashes, it is interpreted as a regular expression.

Normally, only API elements are shown, but if there are no matching API elements but there are some other matching elements, those are shown. This allows you to conveniently find when functions internal to the core implementation were added; only people working on the core are likely to find this last part useful.


In order for a Perl extension (XS) module to be as portable as possible across differing versions of Perl itself, certain steps need to be taken.

  • Including this header is the first major one. This alone will give you access to a large part of the Perl API that hasn't been available in earlier Perl releases. Use

        perl ppport.h --list-provided

    to see which API elements are provided by ppport.h.

  • You should avoid using deprecated parts of the API. For example, using global Perl variables without the PL_ prefix is deprecated. Also, some API functions used to have a perl_ prefix. Using this form is also deprecated. You can safely use the supported API, as ppport.h will provide wrappers for older Perl versions.

  • Although the purpose of ppport.h is to keep you from having to concern yourself with what version you are running under, there may arise instances where you have to do so. These macros, the same ones as in base Perl, are available to you in all versions, and are what you should use:

    PERL_VERSION_xx(major, minor, patch)

    Returns whether or not the perl currently being compiled has the specified relationship xx to the perl given by the parameters. xx is one of EQ, NE, LT, LE, GT, GE.

    For example,

     #if PERL_VERSION_GT(5,24,2)
       code that will only be compiled on perls after v5.24.2
       fallback code

    Note that this is usable in making compile-time decisions

    You may use the special value '*' for the final number to mean ALL possible values for it. Thus,

     #if PERL_VERSION_EQ(5,31,'*')

    means all perls in the 5.31 series. And

     #if PERL_VERSION_NE(5,24,'*')

    means all perls EXCEPT 5.24 ones. And

     #if PERL_VERSION_LE(5,9,'*')

    is effectively

     #if PERL_VERSION_LT(5,10,0)
  • If you use one of a few functions or variables that were not present in earlier versions of Perl, and that can't be provided using a macro, you have to explicitly request support for these functions by adding one or more #defines in your source code before the inclusion of ppport.h.

    These functions or variables will be marked explicit in the list shown by --list-provided.

    Depending on whether you module has a single or multiple files that use such functions or variables, you want either static or global variants.

    For a static function or variable (used only in a single source file), use:

        #define NEED_function
        #define NEED_variable

    For a global function or variable (used in multiple source files), use:

        #define NEED_function_GLOBAL
        #define NEED_variable_GLOBAL

    Note that you mustn't have more than one global request for the same function or variable in your project.


    To avoid namespace conflicts, you can change the namespace of the explicitly exported functions / variables using the DPPP_NAMESPACE macro. Just #define the macro before including ppport.h:

        #define DPPP_NAMESPACE MyOwnNamespace_
        #include "ppport.h"

    The default namespace is DPPP_.

The good thing is that most of the above can be checked by running ppport.h on your source code. See the next section for details.


To verify whether ppport.h is needed for your module, whether you should make any changes to your code, and whether any special defines should be used, ppport.h can be run as a Perl script to check your source code. Simply say:

    perl ppport.h

The result will usually be a list of patches suggesting changes that should at least be acceptable, if not necessarily the most efficient solution, or a fix for all possible problems.

If you know that your XS module uses features only available in newer Perl releases, if you're aware that it uses C++ comments, and if you want all suggestions as a single patch file, you could use something like this:

    perl ppport.h --compat-version=5.6.0 --cplusplus --patch=test.diff

If you only want your code to be scanned without any suggestions for changes, use:

    perl ppport.h --nochanges

You can specify a different diff program or options, using the --diff option:

    perl ppport.h --diff='diff -C 10'

This would output context diffs with 10 lines of context.

If you want to create patched copies of your files instead, use:

    perl ppport.h

To display portability information for the newSVpvn function, use:

    perl ppport.h --api-info=newSVpvn

Since the argument to --api-info can be a regular expression, you can use

    perl ppport.h --api-info=/_nomg$/

to display portability information for all _nomg functions or

    perl ppport.h --api-info=/./

to display information for all known API elements.


Some of the suggested edits and/or generated patches may not compile as-is without tweaking manually. This is generally due to the need for an extra parameter to be added to the call to prevent buffer overflow.

If this version of ppport.h is causing failure during the compilation of this module, please check if newer versions of either this module or Devel::PPPort are available on CPAN before sending a bug report.

If ppport.h was generated using the latest version of Devel::PPPort and is causing failure of this module, please file a bug report at

Please include the following information:

  1. The complete output from running "perl -V"

  2. This file.

  3. The name and version of the module you were trying to build.

  4. A full log of the build that failed.

  5. Any other information that you think could be relevant.

For the latest version of this code, please get the Devel::PPPort module from CPAN.


Version 3.x, Copyright (c) 2004-2013, Marcus Holland-Moritz.

Version 2.x, Copyright (C) 2001, Paul Marquess.

Version 1.x, Copyright (C) 1999, Kenneth Albanowski.

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


See Devel::PPPort.

3 POD Errors

The following errors were encountered while parsing the POD:

Around line 12:

Unknown directive: =provides

Around line 14:

Unknown directive: =dontwarn

Around line 22:

Unknown directive: =implementation