xref: /openbsd/gnu/usr.bin/perl/dist/Devel-PPPort/parts/inc/ppphdoc (revision 9a4edab6)

################################################################################
##
##  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.
##
################################################################################

=provides

=dontwarn

NEED_function
NEED_function_GLOBAL
NEED_variable
NEED_variable_GLOBAL
DPPP_NAMESPACE

=implementation

=pod

=head1 NAME

ppport.h - Perl/Pollution/Portability version __VERSION__

=head1 SYNOPSIS

  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
                              back
  --api-info=name             show Perl API portability information

=head1 COMPATIBILITY

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

=head1 OPTIONS

=head2 --help

Display a brief usage summary.

=head2 --version

Display the version of F<ppport.h>.

=head2 --patch=I<file>

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.

=head2 --copy=I<suffix>

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 C<--patch> or C<--copy> are given, the default is to
simply print the diffs for each file. This requires either
C<Text::Diff> or a C<diff> program to be installed.

=head2 --diff=I<program>

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

=head2 --compat-version=I<version>

Tell F<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 F<ppport.h> if you intend to be backward compatible only
down to a certain Perl version.

=head2 --cplusplus

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

=head2 --quiet

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

=head2 --nodiag

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

=head2 --nohints

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

=head2 --nochanges

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

=head2 --nofilter

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.

=head2 --strip

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

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

=head2 --list-provided

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

=head2 --list-unsupported

Lists the API elements that are known not to be FULLY supported by F<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 F<ppport.h> supports at all.

=head2 --api-info=I<name>

Show portability information for elements matching I<name>.
If I<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.

=head1 DESCRIPTION

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.

=over 4

=item *

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.

=item *

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

=item *

Although the purpose of F<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:

=over 4

=item C<PERL_VERSION_I<xx>(major, minor, patch)>

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

For example,

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

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)

=back

=item *

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 C<#define>s in your source code before the inclusion of F<ppport.h>.

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

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

For a C<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.

    __EXPLICIT_API__

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

    #define DPPP_NAMESPACE MyOwnNamespace_
    #include "ppport.h"

The default namespace is C<DPPP_>.

=back

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

=head1 EXAMPLES

To verify whether F<ppport.h> is needed for your module, whether you
should make any changes to your code, and whether any special defines
should be used, F<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 C<diff> program or options, using
the C<--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 --copy=.new

To display portability information for the C<newSVpvn> function,
use:

    perl ppport.h --api-info=newSVpvn

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

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

to display portability information for all C<_nomg> functions or

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

to display information for all known API elements.

=head1 BUGS

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

If F<ppport.h> was generated using the latest version of
C<Devel::PPPort> and is causing failure of this module, please
file a bug report at L<https://github.com/Dual-Life/Devel-PPPort/issues>

Please include the following information:

=over 4

=item 1.

The complete output from running "perl -V"

=item 2.

This file.

=item 3.

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

=item 4.

A full log of the build that failed.

=item 5.

Any other information that you think could be relevant.

=back

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

=head1 COPYRIGHT

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.

=head1 SEE ALSO

See L<Devel::PPPort>.

=cut