ppport.h - Perl/Pollution/Portability version 3.06_01


  perl ppport.h [options] [source files]

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

  --help                      show short help

  --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

  --list-provided             list provided API
  --list-unsupported          list unsupported API
  --api-info=name             show Perl API portability information


This version of ppport.h is designed to support operation with Perl installations back to 5.003, and has been tested up to 5.9.3.



Display a brief usage summary.


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.

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 5.003. You can use this option to reduce the output of ppport.h if you intend to be backward compatible only up 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.


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.


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 for it.


Lists the API elements that are known not to be supported by ppport.h and below which version of Perl they probably won't be available or work.


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


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.

  • If you use one of a few functions 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 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, you want either static or global variants.

    For a static function, use:

        #define NEED_function

    For a global function, use:

        #define NEED_function_GLOBAL

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

        Function                  Static Request               Global Request
        eval_pv()                 NEED_eval_pv                 NEED_eval_pv_GLOBAL
        grok_bin()                NEED_grok_bin                NEED_grok_bin_GLOBAL
        grok_hex()                NEED_grok_hex                NEED_grok_hex_GLOBAL
        grok_number()             NEED_grok_number             NEED_grok_number_GLOBAL
        grok_numeric_radix()      NEED_grok_numeric_radix      NEED_grok_numeric_radix_GLOBAL
        grok_oct()                NEED_grok_oct                NEED_grok_oct_GLOBAL
        newCONSTSUB()             NEED_newCONSTSUB             NEED_newCONSTSUB_GLOBAL
        newRV_noinc()             NEED_newRV_noinc             NEED_newRV_noinc_GLOBAL
        sv_2pv_nolen()            NEED_sv_2pv_nolen            NEED_sv_2pv_nolen_GLOBAL
        sv_2pvbyte()              NEED_sv_2pvbyte              NEED_sv_2pvbyte_GLOBAL
        sv_catpvf_mg()            NEED_sv_catpvf_mg            NEED_sv_catpvf_mg_GLOBAL
        sv_catpvf_mg_nocontext()  NEED_sv_catpvf_mg_nocontext  NEED_sv_catpvf_mg_nocontext_GLOBAL
        sv_setpvf_mg()            NEED_sv_setpvf_mg            NEED_sv_setpvf_mg_GLOBAL
        sv_setpvf_mg_nocontext()  NEED_sv_setpvf_mg_nocontext  NEED_sv_setpvf_mg_nocontext_GLOBAL
        vnewSVpvf()               NEED_vnewSVpvf               NEED_vnewSVpvf_GLOBAL

    To avoid namespace conflicts, you can change the namespace of the explicitly exported functions 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.

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.


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 using the CPAN Request Tracker 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) 2004-2005, 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.