P5NCI + void load_function-signature

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

hi!

a few days ago i was pointed to P5NCI::Library to interact with C-libraries. i had a closer look at it and it's really useful and great! but by playing around with it, a few problems came up. it seems that load_function does not accept a void-signature. i put up a test-library that takes various arguments. amongst them 'void'. here is the .c-code for the test-library:

#include <stdio.h>
#include <string.h>

char *hello(void)
{
  static char result[]={"hello world"};
  return result;
}

char *bye(char *str)
{
  static char prefix[]={"good bye"};
  static char result[32];
  strcpy(result,prefix);
  strcat(result,str);
  return result;
}

char *return_char(int chr)
{
  static char result[1];
  sprintf(result, "%c", chr);
  return result;
}

int square(int x)
{
  x = (x * x);
  return x;
}

int do_nothing(void)
{
  return 1;
}
[download]

and here is a little test-script using P5NCI::Library to interact with my test-library:

#!/usr/bin/perl

use P5NCI::Library;

my $lib = P5NCI::Library->new( library => 'hello_world', package => 'T
+EST' );

my $test = $lib->install_function( 'hello', 'tv' );
my $hello       = TEST::hello();
print "for hello() i got:          $hello\n";
undef $test;

my $test = $lib->install_function( 'return_char', 'ti' );
my $return_char = TEST::return_char( 65 );
print "for return_char(65) i got:  $return_char\n";
undef $test;

my $test = $lib->install_function( 'square', 'ii' );
my $square      = TEST::square( 3 );
print "for square(3) i got:        $square\n";
undef $test;

my $test = $lib->install_function( 'bye', 'tt' );
my $bye         = TEST::bye( "thanks for all the passwords" );
print "for bye(test) i got:        $bye\n";
undef $test;

my $test = $lib->install_function( 'do_nothing', 'vi' );
my $do_nothing  = TEST::do_nothing();
print "for do_nothing() i got:     $do_nothing\n";
undef $test;
[download]

the functions 'return_char', 'square', and 'bye' work just perfect, but 'hello' and 'do_nothing' do not. both have a void input-signature.
am i doing something wrong, or is P5NCI having troubles with these kind of functions? TIA for any hint.
br, nos

Comment on P5NCI + void load_function-signature Select or Download Code

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Re: P5NCI + void load_function-signature by chromatic (Archbishop) on Jun 22, 2006 at 18:55 UTC
After fixing the signature to `iv`, the code you posted works for me. Do you not have the symbol `XS_P5NCI_nci_iv` defined in your P5NCI.so? If so, I wonder if the generated XS file is incomplete.	[reply] [d/l] [select]
Re^2: P5NCI + void load_function-signature by nostromo (Sexton) on Jun 22, 2006 at 19:20 UTC
indeed a `strings P5NCI.so \| grep XS_P5NCI_nci_iv` shows no hit. hm... the problem might be, that my P5NCI-module was not built via "perl ./Build", but rather by converting a prebuilt package to my needs. today in the morning (localtime, so about 12 hours ago) i tried to compile from tarball. but the build process failed after about an hour :( ok, so it seems my module seems broken. a fact i can live with. thanks a lot, chromatic for helping me on this one! br, nos	[reply] [d/l]
Re^3: P5NCI + void load_function-signature by chromatic (Archbishop) on Jun 22, 2006 at 19:53 UTC
You do need a fair amount of memory to compile the generated XS file. I could probably chunk it into separate files, so as not to choke compilers and machines without spare cycles. If you don't have the right signature, you do need to rebuild it though. (If you want to do that and don't need too much complexity, change `my $max_len = 5;` on line 72 of build_lib/P5NCI/GenerateXS.pm. Reducing that to 4 should make a much smaller, if less capable, XS file.)	[reply] [d/l]
Re^4: P5NCI + void load_function-signature by diotalevi (Canon) on Jun 22, 2006 at 20:21 UTC
Re^5: P5NCI + void load_function-signature by chromatic (Archbishop) on Jun 22, 2006 at 21:55 UTC
Re^4: P5NCI + void load_function-signature by nostromo (Sexton) on Jun 22, 2006 at 20:19 UTC
Re^4: P5NCI + void load_function-signature by samtregar (Abbot) on Jun 23, 2006 at 03:25 UTC
Re^5: P5NCI + void load_function-signature by chromatic (Archbishop) on Jun 23, 2006 at 06:44 UTC
Some notes below your chosen depth have not been shown here
Re: P5NCI + void load_function-signature by samtregar (Abbot) on Jun 22, 2006 at 15:35 UTC
my $test = $lib->install_function( 'do_nothing', 'vi' ); Shouldn't that signature be 'iv'? -sam	[reply]
Re^2: P5NCI + void load_function-signature by nostromo (Sexton) on Jun 22, 2006 at 15:45 UTC
yes, sam, you are right. i tried both, and seems i forgot to paste the latest version of my test-script. nonetheless, it still does not work :( Don't understand NCI signature 'iv' at /usr/share/perl5/P5NCI/Library.pm line 40	[reply]
Re^3: P5NCI + void load_function-signature by samtregar (Abbot) on Jun 22, 2006 at 15:47 UTC
The docs for P5NCI::Library say: This function itself will throw an exception if you fail to provide both a function name and its signature. It will also throw an exception if it does not understand the signature. That might not be an error -- it doesn't understand a lot of valid signatures yet. Looks like you found one it doesn't "understand." -sam	[reply]
Re^4: P5NCI + void load_function-signature by nostromo (Sexton) on Jun 22, 2006 at 16:10 UTC
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