syphilis has asked for the wisdom of the Perl Monks concerning the following question:

Hi,
I've written a test extension (Foo), the full source of which is contained within the readmore tags below my sig. It's a valid source distro - in that it can be built with 'perl Makefile.PL', 'make test' and 'make install'.

It's a bare-bones and useless extension that contains just one XSub named 'foo()'. When I build Foo, I note that the Foo.dll (shared object) that is built does not export 'foo()'. What do I need to do in order that Foo.dll *does* export 'foo()'.

Cheers,
Rob
## Foo.pm ##
package Foo;
use strict;

require Exporter;
*import = \&Exporter::import;
require DynaLoader;

$Foo::VERSION = '0.01';

DynaLoader::bootstrap Foo $Foo::VERSION;

@Foo::EXPORT = qw(foo);
@Foo::EXPORT_OK = ();

sub dl_load_flags {0} # Prevent DynaLoader from complaining and croaki
+ng

1;
__END__


## Makefile.PL ##
use ExtUtils::MakeMaker;
my %options = %{       
{
  'TYPEMAPS' => [
    'C:\\perl510_M\\5.10.0\\lib\\ExtUtils\\typemap'
  ],
  'NAME' => 'Foo',
  'INC' => '-IC:/temp/Foo_build',
  'VERSION' => '0.01'
}
};
WriteMakefile(%options);

# Remove the Makefile dependency. Causes problems on a few systems.
sub MY::makefile { '' }
__END__


## test.pl ##
use Foo;

$x = 17;
$y = 31;

$z = foo($x, $y);
if($z == 48){print "ok 1\n"}
else {print "not ok 1 $z\n"}
__END


// Foo.xs //
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

int foo(int x, int y) {
    return x + y;
}

MODULE = Foo    PACKAGE = Foo    

PROTOTYPES: DISABLE


int
foo (x, y)
    int    x
    int    y

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Re: [XS on Win32] How to have the extension's dll export its symbols.
by BrowserUk (Patriarch) on Mar 05, 2008 at 11:57 UTC
[reply]
[d/l]
      As regards point 1 :
      The def file is auto-generated during the 'make' process - which is 'dmake', in my case. How does one influence the contents of the def file that is created by that automated procedure ?

      As regards point 2 :
      I changed Foo.xs so that it now has: 
      #include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

int __declspec(dllexport) foo(int x, int y) {
    return x + y;
}

MODULE = Foo    PACKAGE = Foo    

PROTOTYPES: DISABLE


int
foo (x, y)
    int    x
    int    y

      [download]
      But, according to dumpbin /exports, 'Foo.dll' still exports only '_boot_Foo' and 'boot_Foo'.

      I'm using the MinGW compiler - don't know if that has any bearing on the matter ... apologies if I'm being dense.

      Cheers,
      Rob
[reply]
[d/l]
[select]
        I'm using the MinGW compiler ...

        If you follow the link I belatedly added to my response you'll see that dllexport is an MS specific extension. Presumably the __declspec() bit is a part of some standard otherwise you'd be getting an error.

        Whether MinGW supports a similar extension I don't know. They can build .sos an .dlls so must have encountered similar problems.

        1. How does one influence the contents of the def file that is created by that automated procedure ?

          I looked that up a while ago. There is mention in the pod for E::MM of a coniguration attribute DL_FUNCS which seems to be something to do with it.

        2. I changed Foo.xs so that it now has:

          See above:)

        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
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