NAME
Module::Build::WithXSpp - XS++ enhanced flavour of Module::Build
SYNOPSIS
In Build.PL:
use strict;
use warnings;
use 5.006001;
use Module::Build::WithXSpp;
my $build = Module::Build::WithXSpp->new(
# normal Module::Build arguments...
# optional: mix in some extra C typemaps:
extra_typemap_modules => {
'ExtUtils::Typemaps::ObjectMap' => '0',
},
);
$build->create_build_script;
DESCRIPTION
This subclass of Module::Build adds some tools and processes to make it
easier to use for wrapping C++ using XS++ (ExtUtils::XSpp).
There are a few minor differences from using "Module::Build" for an
ordinary XS module and a few conventions that you should be aware of as
an XS++ module author. They are documented in the "FEATURES AND
CONVENTIONS" section below. But if you can't be bothered to read all
that, you may choose skip it and blindly follow the advice in "JUMP
START FOR THE IMPATIENT".
An example of a full distribution based on this build tool can be found
in the ExtUtils::XSpp distribution under examples/XSpp-Example. Using
that example as the basis for your "Module::Build::WithXSpp"-based
distribution is probably a good idea.
FEATURES AND CONVENTIONS
XS files
By default, "Module::Build::WithXSpp" will automatically generate a main
XS file for your module which includes all XS++ files and does the
correct incantations to support C++.
If "Module::Build::WithXSpp" detects any XS files in your module, it
will skip the generation of this default file and assume that you wrote
a custom main XS file. If that is not what you want, and wish to simply
include plain XS code, then you should put the XS in a verbatim block of
an .xsp file. In case you need to use the plain-C part of an XS file for
"#include" directives and other code, then put your code into a header
file and "#include" it from an .xsp file:
In src/mystuff.h:
#include <something>
using namespace some::thing;
In xsp/MyClass.xsp
#include "mystuff.h"
%{
... verbatim XS here ...
%}
Note that there is no guarantee about the order in which the XS++ files
are picked up.
Build directory
When building your XS++ based extension, a temporary build directory
buildtmp is created for the byproducts. It is automatically cleaned up
by "./Build clean".
Source directories
A Perl module distribution typically has the module ".pm" files in its
lib subdirectory. In a "Module::Build::WithXSpp" based distribution,
there are two more such conventions about source directories:
If any C++ source files are present in the src directory, they will be
compiled to object files and linked automatically.
Any ".xs", ".xsp", and ".xspt" files in an xs or xsp subdirectory will
be automatically picked up and included by the build system.
For backwards compatibility, files of the above types are also
recognized in lib.
Typemaps
In XS++, there are two types of typemaps: The ordinary XS typemaps which
conventionally put in a file called typemap, and XS++ typemaps.
The ordinary XS typemaps will be found in the main directory, under lib,
and in the XS directories (xs and xsp). They are required to carry the
".map" extension or to be called typemap. You may use multiple .map
files if the entries do not collide. They will be merged at build time
into a complete typemap file in the temporary build directory.
The "extra_typemap_modules" option is the prefered way to do XS
typemapping. It works like any other "Module::Build" argument that
declares dependencies except that it loads the listed modules at build
time and includes their typemaps into the build.
The XS++ typemaps are required to carry the ".xspt" extension or (for
backwards compatibility) to be called "typemap.xsp".
Detecting the C++ compiler
"Module::Build::WithXSpp" uses ExtUtils::CppGuess to detect a C++
compiler on your system that is compatible with the C compiler that was
used to compile your perl binary. It sets some additional
compiler/linker options.
This is known to work on GCC (Linux, MacOS, Windows, and ?) as well as
the MS VC toolchain. Patches to enable other compilers are very welcome.
Automatic dependencies
"Module::Build::WithXSpp" automatically adds several dependencies (on
the currently running versions) to your distribution. You can disable
this by setting "auto_configure_requires => 0" in Build.PL.
These are at configure time: "Module::Build", "Module::Build::WithXSpp"
itself, and "ExtUtils::CppGuess". Additionally there will be a
build-time dependency on "ExtUtils::XSpp".
You do not have to set these dependencies yourself unless you need to
set the required versions manually.
Include files
Unfortunately, including the perl headers produces quite some pollution
and redefinition of common symbols. Therefore, it may be necessary to
include some of your headers before including the perl headers.
Specifically, this is the case for MSVC compilers and the standard
library headers.
Therefore, if you care about that platform in the least, you should use
the "early_includes" option when creating a "Module::Build::WithXSpp"
object to list headers to include before the perl headers. If such a
supplied header file starts with a double quote, "#include "..."" is
used, otherwise "#include <...>" is the default. Example:
Module::Build::WithXSpp->new(
early_includes => [qw(
"mylocalheader.h"
<mysystemheader.h>
)]
)
JUMP START FOR THE IMPATIENT
There are as many ways to start a new CPAN distribution as there are
CPAN distributions. Choose your favourite (I just do "h2xs -An
My::Module"), then apply a few changes to your setup:
* Obliterate any Makefile.PL.
This is what your Build.PL should look like:
use strict;
use warnings;
use 5.006001;
use Module::Build::WithXSpp;
my $build = Module::Build::WithXSpp->new(
module_name => 'My::Module',
license => 'perl',
dist_author => q{John Doe <john_does_mail_address>},
dist_version_from => 'lib/My/Module.pm',
build_requires => { 'Test::More' => 0, },
extra_typemap_modules => {
'ExtUtils::Typemaps::ObjectMap' => '0',
# ...
},
);
$build->create_build_script;
If you need to link against some library "libfoo", add this to the
options:
extra_linker_flags => [qw(-lfoo)],
There is "extra_compiler_flags", too, if you need it.
* You create two folders in the main distribution folder: src and xsp.
* You put any C++ code that you want to build and include in the module
into src/. All the typical C(++) file extensions are recognized and
will be compiled to object files and linked into the module. And
headers in that folder will be accessible for "#include <myheader.h>".
For good measure, move a copy of ppport.h to that directory. See
Devel::PPPort.
* You do not write normal XS files. Instead, you write XS++ and put it
into the xsp/ folder in files with the ".xsp" extension. Do not worry,
you can include verbatim XS blocks in XS++. For details on XS++, see
ExtUtils::XSpp.
* If you need to do any XS type mapping, put your typemaps into a .map
file in the "xsp" directory. Alternatively, search CPAN for an
appropriate typemap module (cf. ExtUtils::Typemaps::Default for an
explanation). XS++ typemaps belong into .xspt files in the same
directory.
* In this scheme, lib/ only contains Perl module files (and POD). If you
started from a pure-Perl distribution, don't forget to add these magic
two lines to your main module:
require XSLoader;
XSLoader::load('My::Module', $VERSION);
SEE ALSO
Module::Build upon which this module is based.
ExtUtils::XSpp implements XS++. The "ExtUtils::XSpp" distribution
contains an examples directory with a usage example of this module.
ExtUtils::Typemaps implements progammatic modification (merging) of C/XS
typemaps. "ExtUtils::Typemaps" was renamed from "ExtUtils::Typemap"
since the original name conflicted with the core typemap file on
case-insensitive file systems.
ExtUtils::Typemaps::Default explains the concept of having typemaps
shipped as modules.
ExtUtils::Typemaps::ObjectMap is such a typemap module and probably very
useful for any XS++ module.
ExtUtils::Typemaps::STL::String implements simple typemapping for STL
"std::string"s.
AUTHOR
Steffen Mueller <smueller@cpan.org>
With input and bug fixes from:
Mattia Barbon
Shmuel Fomberg
COPYRIGHT AND LICENSE
Copyright 2010, 2011 Steffen Mueller.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
POD ERRORS
Hey! The above document had some coding errors, which are explained
below:
Around line 717:
You forgot a '=back' before '=head1'