Trees using Inline::C

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

Dear monks,

I am trying to apply the OO cookbook example for Inline::C to a situation where one has objects related in a parent->offspring relationship, so that you can instantiate a node (e.g. with a name, a description, and a branch-length), instantiate another node, and set one as the parent of the other - and subsequently retrieve it. Alas, I have to admit I don't know enough about the perl guts to know what to return from a $child->get_parent call. Has anyone else worked along similar lines (but *with* success)? I've appended an example of what I'm trying to achieve. Thank you for any and all pointers!


# Please fill in all missing code and fix the bugs below ;-)

#---------------------------------------------------------

#!/usr/bin/perl
use strict;
use warnings;

my $node   = Node->new('Homo_sapiens', 'Hominid', 1.234);
my $parent = Node->new('Homo_neanderthalensis', 'Hominid', 5.02);

$node->set_parent($parent);
# $node->get_parent;

#---------------------------------------------------------

package Node;
use Inline Config => BUILD_NOISY => 1;
use Inline C => 'DATA', NAME => 'Node';

__DATA__
__C__
typedef struct treeNode {
   char*  name;
   char*  desc;
   double branch_length;
   struct treeNode *parent;
} Node;

SV* new(char* class, char* name, char* desc, double branch_length) {
   Node* node          = malloc(sizeof(Node));
   SV* obj_ref         = newSViv(0);
   SV* obj             = newSVrv(obj_ref, class);
   node->name          = savepv(name);
   node->desc          = savepv(desc);
   node->branch_length = branch_length;
   sv_setiv(obj, (IV)node);
   SvREADONLY_on(obj);
   return obj_ref;
}

void set_parent(SV* obj, SV* parent) {
   /* this ought to work, no? */
   ((Node*)SvIV(SvRV(obj)))->parent = (Node*)SvIV(SvRV(parent));
}

SV* get_parent(SV* obj) {
   /* ...erm...? */
}

void DESTROY(SV* obj) {
   Node* node = (Node*)SvIV(SvRV(obj));
   Safefree(node->name);
   Safefree(node);
}
[download]

Comment on Trees using Inline::C Download Code

Replies are listed 'Best First'.
Re: Trees using Inline::C by esskar (Deacon) on Aug 01, 2005 at 00:03 UTC
`SV* get_parent(SV* obj) { Node node = (Node )SvIV(SvRV(obj)); if(node != NULL && node->parent != NULL) return new( "Node", node->parent->name, node->parent->desc, node->parent->branch_length ); else return NULL; // not sure }` [download] but i would prefer to set parent to NULL inside the new function, and add an iditional member named "class" to your struct treeNode to ensure the same class name	[reply] [d/l]
Re^2: Trees using Inline::C by rvosa (Curate) on Aug 01, 2005 at 00:31 UTC
Thanks for your reply! But, is that efficient memory usage? Memory has already been allocated when: `my $parent = Node->new('Homo_neanderthalensis', 'Hominid', 5.02);` [download] was called, and it seems like this new call to `return new( /..etc.../);` [download] goes the same route? Or am I missing something? Thanks again!	[reply] [d/l] [select]
Re^3: Trees using Inline::C by esskar (Deacon) on Aug 01, 2005 at 08:22 UTC
sure. you are right; but see, a (Node ) has no information about its (SV ). A workaround would be typedef struct treeNode { char* name; char* desc; char* class; //in case we need it double branch_length; SV* obj; // the perlobj SV* obj_ref; // the ref to the perlobj struct treeNode parent; } Node; SV new(char* class, char* name, char* desc, double branch_length) { Node* node = malloc(sizeof(Node)); node->obj_ref = newSViv(0); node->obj = newSVrv(obj_ref, class); node->class = savepv(class); node->name = savepv(name); node->desc = savepv(desc); node->branch_length = branch_length; node->parent = NULL; // no parent yet sv_setiv(node->obj, (IV)node); SvREADONLY_on(node->obj); return node->obj_ref; } SV* get_parent(SV* obj) { Node node = (Node )SvIV(SvRV(obj)); if(node != NULL && node->parent != NULL) return node->parent->obj_ref; else return NULL; // not sure } [download] HTH	[reply] [d/l]
Re^4: Trees using Inline::C by rvosa (Curate) on Aug 01, 2005 at 14:42 UTC