Re: [boost] deleting smart pointer

Subject: Re: [boost] deleting smart pointer
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2011-03-18 18:31:51

AMDG

On 03/18/2011 01:54 PM, pavel wrote:
>   Steven wrote on Friday, March 18, 2011 at 21:02:13:
>> Second, how is it horrible?  Of course it is (almost) like
>> p.reset().  Assigning anything to a shared_ptr
>> decrements the reference count on the old value.
> rephrasing your words: how is 'delete p' a bad idea? it's obvious it
> is almost like 'p.reset()'

No it isn't.  The difference is that assignment
is a basic operation for a smart_ptr, and it's
behaving in the normal way.  It isn't a matter
of being "almost like" reset.

>> Except that the tricks you use to implement
>> it result in undefined behavior...
> i inspected the std and didn't find anything which may result in
> undefined behavior
>
> did i miss anything?
>

[expr.delete]

"...In the first alternative (delete object), the value of the operand 
of delete may be a null pointer
value, a pointer to a non-array object created by a previous 
new-expression, or a pointer to a subobject (1.8)
representing a base class of such an object (Clause 10). If not, the 
behavior is undefined."

In Christ,
Steven Watanabe