I know little about XS modules but I was looking at RPi::DHT11 and noticed that it is an XS module which seemed a little strange. Hence the question here. I was going to email stevieb, the author and ask but thought it would be good to get other people's take on this.

My understanding of an XS module is that it uses XSLoader to load C / C++ / C# code. The Perl is just a wrapper around the loaded code with the Perl doing little processing. I believe the main reason to do this is for speed as compiled languages of the C family are faster than interpreted languages such as Perl. Is that about right so far?

Assuming that is something like correct...
Why would the RPi::DHT11 module use XS? The DHT11 is a temperature and humidity sensor with a maximum frequency of 0.5Hz (one read per 2 seconds). So speed is not the issue here!

What reason would there be for creating an XS module in this use case? Would it not be easier and simpler and just as fast given the speed of the sensor, to write all the code in Perl?

I'm hoping for more insights into the world of XS modules here...

My module does not need to use unicode. If the unicode comments and POD were stripped out of it, it would not even require "use utf8;" as there is no unicode in its actual code. But because it is for utf8 and the tests, to be meaningful, incorporate uft8 characters, the entire module fails to install on perl systems which do not already have the non-core module "Test::More::UTF8."

In order to make the installation as easy and fuss-free as possible, and more space-conserving, too, I don't want to require the installation of non-core modules. If there is not a better way to do this, my next version release will abandon all of those useful tests and put in one or more tests which require no unicode at all--just a "free pass" so to speak. This way, at least, the install would be able to complete.

So the question remains, is it even possible to create, and install, a module designed for Perl 5.8.3 compatibility, that provides UTF8 functions, and that does not require any non-core modules--and do this with reasonable UTF8-based tests?

I think I've managed to find a hackish solution that should get me by for now. I've dumped once again (I should not have gone back to it after dropping it the first time) the "Test::More::UTF8" package earlier thought to be a "solution" for the lack of UTF8 compatibility of Test::More...it wasn't, and even when the package was manually installed (not part of core), it tended to generate some inexplicable 'wide character' warnings. So, I went with a pure-ASCII solution, no need even for "use utf8" in the testing script. Instead of testing on actual UTF8 characters, the script now tests on the hexadecimal codepoints returned from the module. If the correct codepoint is returned, the function can legitimately be considered to be installed and functioning. It would have been nice to test on real unicode, but oh well...the module will still work just fine, I'm sure.

 these are the constants from cryptfix
# use constant APOSTROPHE => "’" ;
# use constant OPENQUOTE =>  "“" ;
# use constant CLOSEQUOTE => "”" ;
# use constant COMMA      => "¸" ;

# This is the version from a hex dump of the crypt text file
use constant APOSTROPHE => "\x{e2}\x{80}\x{22}" ;
use constant OPENQUOTE =>  "\x{e2}\x{80}\x{90}" ;
use constant CLOSEQUOTE => "\x{e2}\x{80}\x{9d}" ;
use constant COMMA      => "¸" ;


unless (@ARGV)
{   die "usage: <crypts-text-file>\n" ; }

open(CRYPTS, "<",  $ARGV[0]) or die "Can't open $ARGV[0]: $!" ;
while (my $line = <CRYPTS>)
{   say "apostrophe in line $." if $line =~ /@{[APOSTROPHE]}/;
    say "open quote in line $." if $line =~ /@{[OPENQUOTE]}/;
    say "close quote in line $." if $line =~ /@{[CLOSEQUOTE]}/;
}
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I get this weird error when using the JSON or JSON::XS module:

$ perl -MJSON -e ''

XS.c: loadable library and perl binaries are mismatched (got first handshake key 0xeb80080, needed 0xf380080)

And the same error for perl -MJSON::XS -e ''

perl -v
This is perl 5, version 38, subversion 0 (v5.38.0) built for x86_64-li
+nux-thread-multi
...
[download]

What could cause this, and what can I do to fix it?

Hi Monks,

Today I've started to study perlembed, Here is the first code example in Perlembed:

#include <EXTERN.h>               /* from the Perl distribution     */
 #include <perl.h>                 /* from the Perl distribution     *
+/

 static PerlInterpreter *my_perl;  /***    The Perl interpreter    ***
+/

 int main(int argc, char **argv, char **env)
 {
    PERL_SYS_INIT3(&argc,&argv,&env);
        my_perl = perl_alloc();
        perl_construct(my_perl);
    PL_exit_flags |= PERL_EXIT_DESTRUCT_END;
        perl_parse(my_perl, NULL, argc, argv, (char **)NULL);
        perl_run(my_perl);
        perl_destruct(my_perl);
        perl_free(my_perl);
    PERL_SYS_TERM();
    exit(EXIT_SUCCESS);
 }
[download]

#include <EXTERN.h>
#include <perl.h>



 static PerlInterpreter *his_perl ;  /***    The Perl interpreter    *
+**/

 int main(int argc, char **argv, char **env)
 {

    PERL_SYS_INIT3(&argc,&argv,&env);
      
    PERL_SYS_TERM();  his_perl = perl_alloc();
        perl_construct(his_perl);
        PL_exit_flags |= PERL_EXIT_DESTRUCT_END;
        perl_parse(his_perl, NULL, argc, argv, (char **)NULL);
        perl_run(his_perl);
        perl_destruct(his_perl);
        perl_free(his_perl);
    exit(EXIT_SUCCESS);
 }
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$str1='LFGSLSIIVAHHM';
$str2='LFGSLSIIVSHHM';
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111362894.832068 starman master 24776: segfault at c1 ip 00007f29bd8d2057 sp
 00007fff6ba44168 error 4 in XS.so7f29bd8cf000+15000

[Unit]
Description=StarmanService

[Service]
Type=simple
User=starman
Group=starman
ExecStart=/home/starman/perl5/bin/starman -E debug --ssl-key=/home/sta
+rman/starm
anpem+5-key.pem --ssl-cert=/home/starman/starmanpem+5.pem --listen :50
+00:ssl --w
orkers=1 /home/starman/app.psgi --access-log /home/starman/access.log 
+--user=sta
rman --error-log /home/starman/error1.log
Restart=always
WorkingDirectory=/home/starman/cgi-bin

[Install]
WantedBy=multi-user.target
[download]