suggestion: harness destructor in scoped_ptr<>::reset

From: jlehrer (boost_at_[hidden])
Date: 2002-04-02 11:36:27

Before I propose this to main boost mailing list, I wanted to see 
what others thought of this idea.

I propose changing the following method on scoped_ptr<>:

void reset(T* p=0) {if(ptr!=p) {checked_delete(ptr); ptr=p;}}

to

void reset(T* p=0) {if(ptr!=p) {scoped_ptr<T>(p).swap(*this);}}
void swap(scoped_ptr<T>& other) {std::swap(ptr,other.ptr);}

Of course, we would then have global methods for std::swap, as there 
are for the other smart pointers, to map to this method.

Finally, the same change should be made to scoped_array<>.  
shared_ptr<> and shared_array<> already have these semantics.

The idea is to harness the destructor of the scoped_ptr in order to 
delete the pointer, rather than calling checked_delete in two places.

This has a few advantages over the old code:

1- destruction is handled in one place, the destructor.  This seems 
natural, and gives developers one place to look to see what happens 
when a pointer is deleted

2- I have had occasion to specialize the destructor of the 
scoped_ptr<> class to do something other than delete.  In that case, 
I needed to specialize the destructor AND the reset method.  With 
this change, one would only need to specialize the destructor and 
reset would harness that specialization as well.

Comments?