Deleting Pointers To Const

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2 total messages Started by Alexander J. Oss Fri, 17 Nov 1995 16:41

#2631

Author: Alexander J. Oss
Date: Fri, 17 Nov 1995 16:41

33 lines
1534 bytes

I've looked in sections 3.7.3.2 and 5.3.5 of the April 28th draft and didn't 
see anything concerning the deletion of pointers to const (except that you 
shouldn't use already-deallocated modifiable lvalues).

I get an error saying "Cannot convert 'const int *' to 'void *' in function 
Holder<int>::~Holder()" using TC++ 4.5 for the following code:

template <class T>
class Holder
{
	const T *object;
public:
	Holder(const T *src) { object = src; }
	virtual ~Holder(); { delete object; }
};

int main()
{
	Holder<int> h(new int(5));
	return(0);
}

When I change the destructor to 

	virtual ~Holder(); { delete const_cast<T *>(object) }

all is well!  Why is that?


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Re: Deleting Pointers To Const

#2716

Author: Fergus Henderson
Date: Thu, 23 Nov 1995 03:05

21 lines
1489 bytes

"Alexander J. Oss" <alex.oss@films.com> writes:

>I've looked in sections 3.7.3.2 and 5.3.5 of the April 28th draft and didn't 
>see anything concerning the deletion of pointers to const (except that you 
>shouldn't use already-deallocated modifiable lvalues).

That's right - it's OK to delete pointers to const.  It used to be
illegal, but the committee changed this at the November meeting last year.

>I get an error saying "Cannot convert 'const int *' to 'void *' in function 
>Holder<int>::~Holder()" using TC++ 4.5 for the following code:

Your compiler is out-of-date.  Time to get a new one ;-)

--
Fergus Henderson             	WWW: http://www.cs.mu.oz.au/~fjh
fjh@cs.mu.oz.au              	PGP: finger fjh@128.250.37.3

[ comp.std.c++ is moderated.  Submission address: std-c++@ncar.ucar.edu.
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