Easy way to implement XS using multiple modules

Perl
XS
here

When I tried to make a module using XS, I suddenly had a problem when dividing it into multiple modules. For example, if you want to implement XS with both SomeModule and SomeModule::Util. I was investigating the method, but I found the implementation method to be quite complicated and difficult.

I tried various things, but the next method seemed to be easy, so I will introduce it. The advantages of this method are:

No need to modify Makefile.PL
No need to modify the name of the file SomeModule.xs
Only one XS file called SomeModule.xs is OK
The standard tool h2xs is fine

Create a module with h2xs

First, create a module for XS with h2xs.

h2xs -A -n SomeModule

This will create a directory called "SomeModule". The following files and directories will be created.

Changes
lib/Makefile.PL
MANIFEST
ppport.h
README
SomeModule.xs
t/</pre>

<h4>XS file description</h4>

I will create an XS file. Let's add a function called foo that displays "foo" to SomeModule, and a function called bar that displays "bar" to SomeModule::Util.

First of all, when you open the XS file, you should see something like the following.

<pre>
# include "EXTERN.h"
# include "perl.h"
# include "XSUB.h"

# include "ppport.h"


MODULE = SomeModule PACKAGE = SomeModule

The first thing to remember is that the "MODULE = SomeModule PACKAGE = SomeModule" section should be at the bottom. If you do not leave this part at the end, the XS will fail to load.

Let's write it. Add "MODULE = SomeModule::Util PACKAGE = SomeModule::Util". Then define bar in XS. Also, define foo in the section "MODULE = SomeModule PACKAGE = SomeModule".

# include "EXTERN.h"
# include "perl.h"
# include "XSUB.h"

# include "ppport.h"

MODULE = SomeModule::Util PACKAGE = SomeModule::Util

void
bar (...)
  PPCODE:
{
  PerlIO_printf(PerlIO_stdout (), "bar\n");
  XSRETURN (0);
}

MODULE = SomeModule PACKAGE = SomeModule

void
foo (...)
  PPCODE:
{
  PerlIO_printf(PerlIO_stdout (), "foo\n");
  XSRETURN (0);
}

Creating a module

At this point, all you have to do is create SomeModule and SomeModule::Util.

SomeModule source code

You can leave the source code for SomeModule.pm as it is. I organized it a little and made it as follows.

package SomeModule;

use strict;
use warnings;

our $VERSION = '0.01';

require XSLoader;
XSLoader::load ('SomeModule', $VERSION);

1;

SomeModule::Util source code

Let's also create SomeModule::Util::bar. Save this in "lib/SomeModule/Util.pm". This is an almost empty file with only the package name declared.

package SomeModule::Util;

1;

Test script

Create a test script. This should be in the same directory where the XS files are located.

use strict;
use warnings;

use SomeModule;
use SomeModule::Util;

SomeModule::foo ();
SomeModule::Util::bar ();

Compile and run

Let's compile and run it.

perl Makefile.PL
make
perl -Mblib test.pl

If the output is as follows, it is successful.

foo
bar

Writing XS in multiple modules doesn't seem to be that difficult.

Perl ABC