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We have embedded perl with c++ on a win32 environment to be able to use scripting power in one of our applications. We are able to read-write from perl to C++ and vice versa. We are trying to pass a structure from C++ to perl but are in failure. We can pass variables without a problem. We are still trying to figure some stuff out. We will have nearly 1 million members in our tree, so passing 1 by 1 is out of the question. Are we suppose to map them all 1 by 1 as well in our C++ code ? Isnt there a simpler or faster way of doing this ?? Please remember we are Win32 programmers and not Perl programmers, though we have had some perl experience prior version 5.

We are not expecting full codes. Please just point us in the right direction. Thank you :) !!

The structure we want is something like this

 struct somestruct <-----------
 {
     int count; <--- This number could be from 25 to 25000
    someotherstruct * pdata; <--- Obviously this number will match as 
+well
 }

 struct someotherstruct
 {
<--- This structure can contain alot ...

     vectorstruct vSomething;
     vectorstruct vSomethingElse;
    float, int, char, and what not...
 }

 ...
[download]

Below is our testing code, mostly based on Perldoc, PerlEmbed and PerlCall
Link

************

// all the rest is temp : figuring this perl thing out...

char * cpArguments[] = { "", "test1.pl" };

my_perl = perl_alloc();
ISNOTNULLRETURN(my_perl, "WinMain : NULL my_perl", "Error", -1);
perl_construct(my_perl);

PL_exit_flags |= PERL_EXIT_DESTRUCT_END;
perl_parse(my_perl, NULL, 2, cpArguments, (char **)NULL);

// run script
// perl_run(my_perl);

// run sub from script
// char * cpArgumentsToSub[] = { NULL };
// call_argv("OnUpdate", G_DISCARD | G_NOARGS, cpArgumentsToSub);

// run sub from script passing 2 vars into @_ (simple test).
// ref http://www.apl.jhu.edu/Misc/Unix-info/perl/perlcall.html
{
    SAFEMALLOCI(char, cpBuf, "WinMain : memory allocation failed", -1,
+ 1000);

    int a = 243;
    int b = 527;

    dSP;
           int count;

    SV * sva; //= NULL ?
    SV * svb; //= NULL ?

           ENTER;
           SAVETMPS;

    sva = sv_2mortal(newSViv(a));
           svb = sv_2mortal(newSViv(b));

           PUSHMARK(sp);
           XPUSHs(sva);
           XPUSHs(svb);
    PUTBACK;

           count = perl_call_pv("OnUpdate", G_DISCARD);

    if (count != 0) { croak("wtf\n"); BOX("wtf\n", "Error"); }

    int newa = SvIV(sva);
    int newb = SvIV(svb);

    sprintf (cpBuf, "A [ original = %d modified = %d ]\nB [ original =
+ %d modified = %d ]", a, newa, b, newb);
    BOX(cpBuf, "Debug");

           FREETMPS;
           LEAVE;

    SAFEFREE(cpBuf);
}

perl_destruct(my_perl);
perl_free(my_perl);
[download]

Our perl script :

#!perl

use strict;

sub OnUpdate
{
    ########################################
    # get data
    ########################################
    my ($a, $b) = @_;

    ########################################
    # code using the names
    ########################################
    $a = 5;
    $b = 3;

    ########################################
    # send data
    ########################################
    $_[0] = $a;
    $_[1] = $b;
}
[download]

So having $_[0] to $_[possibly up to 1 million] sounds like a very bad idea to us. We think perl supports structure like variables. We have seen things like, $bleh->sub.
This would be something we would want :

my $data = shift;

for (my $i=0; $i<$data->count; $i++)
{
        $data->pdata[$i]->vsomething->x = $whatever;
}
[download]

Obviously again :), this creates a problem with the "send data" part of the perl script.

Would there be a way to directly modify the memory wihtout reassigning $_[n].
We are not expecting full codes. Please just point us in the right direction. Thank you :) !!

Any help is very appreciated. Thank you for reading

In reply to Embedding Perl / C++ structure question by TheGeniuS

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