Re: [Boost-users] intrusive list with pointer_plus_bit

2008/5/15 Ion Gaztañaga :

Christian Holmquist wrote:

...

Hi,

I have a class X : public intrusive::list_base_hook<> and would like to embed an additional member bool using the pointer_plus_bit.

Can this be achieved using the value_traits somehow, and have the list working 'appropriately'?

It can be achieved using value_traits. Just repeat the following example:

http://www.boost.org/doc/libs/1_35_0/doc/html/intrusive/value_traits.html#in...

but instead of defining this value_traits:

//Define the node traits. A single node_traits will be enough. struct simple_node_traits { typedef simple_node node; typedef node * node_ptr; typedef const node * const_node_ptr;

static node *get_next(const node *n) { return n->next_; } static void set_next(node *n, node *next) { n->next_ = next; } // ... };

Use this (supposing you want to embed the bit in the next pointer):

struct simple_node_traits { // ...

static node *get_next(const node *n) { return pointer_plus_bit::get_pointer(n->next_); }

fails to compile due to n->next_ points to void* and not node*. is it safe to use static_cast(n->next_) here?

FYI, I've just erased pointer_plus_bit.hpp and substituted it with a more generic pointer_plus_bits.hpp in Trunk. Now that I see that it's being used, I will need to provide backwards compatibility.

Ah well,it's not production code, so to me it's not important with backward compatibility. What I'm trying to do is to build a rollback mechanism that's more robust to exceptions due to failing memory allocations. since i'm doing some optimizations on the way, it just seemed as a good idea using the pointer_plus_bit feature. BI is a great lib by the way, the most inspiring addition to boost in 1.35 (although I've been using it from trunk for quite a while)!

I hope it works,

Ion _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users