All,
I rarely try and mix C and perl. When I do, I use Inline::C very sparingly and then use tools to convert to XS for me. I am not a very strong C programmer to begin with so I haven't ever bothered to try and digest the perl API other than whatever that one little bit is to get whatever my current dilema working. Ok, now with that disclaimer of ignorance out of the way, I would like to know how to keep a variable created in C land "alive" when passed back to perl and then back to another C function. Here it is in very broken pseudo code 

my $tree = new_tree();

print node_count($tree), "\n";
__END__
__C__

typedef struct {
      int  count;
} Tree;


SV* new_tree () {
    Tree* tree;
    tree.count = 0;
    /* return tree some how */
}

int node_count (SV* tree) {
    /* get back at tree some how */
    return tree.count;
}

[download]

I have seen the Inline::C-Cookbook example of OO. I don't want an object. If this were pure C, I would pass in a pointer to new_tree and not return anything (glossing over malloc and free). In the CB, tye mentioned "allocate PV space in an SV and stuff it there" which conceptually I understand but have no idea on the implementation. Feel free to mention perlapi, perlxstut, perlguts illustrated, etc though I have all of them on my reading list. I would like a working example to play with as I read though. I know this means I am going to have to handle memory management myself and I am fine with that.

Thanks in advance.

Cheers - L~R

In reply to How to keep C variables "alive" between invocations with Inline::C by Limbic~Region

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