[Boost-users] [smart_ptr] Resetting an intrusive_ptr

From: Scott Meyers (usenet_at_[hidden])
Date: 2006-05-01 19:28:47

Suppose I have an auto_ptr, shared_ptr, or scoped_ptr.  If I want to set it to 
null, I do this (assuming the pointer is named p):

   p.reset();          // okay

If I try this,

   p = 0;              // error

I get an error during compilation.  In other words, reset works, but assignment 
of the null pointer does not.

But suppose p is an intrusive_ptr.  Now

   p.reset();          // error

fails, and

   p = 0;              // okay

succeeds.  In other words, assignment works, but reset does not.  I find this, 
er, unintuitive.  Does anybody know why intrusive_ptr marches to its own 
nullifying drummer?

Thanks,

Scott