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From: Marco Manfredini <marco@technoboredom.net>
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Subject: Re: why doesn't delete NULL the pointer?
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p2sam@uwaterloo.ca (Pedro Sam) wrote:

> Hi all,
> 
> I'm curious about the delete operator and NULL pointers.  Why doesn't
> the standard require that the delete operator to set the pointer's value
> to NULL? 

You weren't able to do this anymore: 

struct A {}; 
struct X
{
	A * const a; 
	X() : a(new A) { }
	~X() { delete a; }
}; 
 
> 
> If the pointer is NULL, then if someone comes along and try to access
> that pointer, it would crash with a segfault, instead of reading garbage
> ( or even worse, write over some memory ).
> 
> Crash early is a Good Thing(TM) right?

Accessing a pointer after it has been deleted is a lesser source of errors 
and it's almost always easy to find. The 'real' kind of error occurs when 
you access deleted memory through an aliased pointer: The is much harder to 
track, happens more frequently (at least to the unstructured programmer) and 
can't be covered by a modifing delete.

If you want this kind of delete, define one:
 
template<class T>
void destroy(T * &t) 
{
 delete t; 
 t=NULL; 
}   

Marco

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