John Torjo wrote:
Peter Dimov wrote:
John Torjo wrote:
Hi Peter,
Just a thought: perhaps this constructor: explicit shared_ptr(weak_ptr<Y> const & r);
should be private, and the only way to create a shared_ptr from a weak_ptr is:
shared_ptr<T> val = weak->lock();
This way, the shared_ptr public constructors will never throw. Users will not make mistakes like this:
shared_ptr<T> val = weak;
This shouldn't compile on a reasonably compliant compiler, because the constructor is explicit.
True, sorry, I meant this:
shared_ptr<T> val(weak);
The point still remains.
I'm not sure that it does. The canonical way to work with a weak_ptr is if( shared_ptr<T> p = weak.lock() ) { // do things with *p } You can't accidentally omit the lock(), and shared_ptr<T> p( weak ) is invalid in an if statement. shared_ptr<T> val( weak ); does exactly what it is intended to do.