On 3/16/2011 3:23 PM, pavel novikov wrote:
i'm excited to present you a technique which i occasionally invented shared pointers are very good helpers they help us to manage dynamically allocated memory however it seems so natural i have never seen so far that one be allowed to delete shared pointer like this:
shared_ptr<int> p = new int, q = p; delete p; assert(!p); //neither assertion fires assert(q);
in fact the technique is rather trivial provide a distinct class like this:
template<typename type> struct deleter : shared_ptr_base<type> { void operator delete(void *p) { reinterpret_cast<ptr_base*>(p)->detach(); } };
and let the 'operator unspecified_type_convertible_to_bool()' return statically casted address of the ptr instance itself (or NULL) like this:
template<typename type> inline shared_ptr<type>::operator const deleter<type>*() const { if (!data) return 0; const shared_ptr_base<type> *base = this; return static_cast<const safe_deleter<type>*>(base); //oops! a little hack... }
minimum changes are needed to the existing library sources this way the example above works perfectly
codepad.org is down so i just attached a toy programm with an implementation of this technique (works at least in msvc10)
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Maybe I'm missing something but how is "delete p;" different from "p.reset();" ?