Re: Avoiding destruction of object

From:

=?ISO-8859-1?Q?=D6=F6_Tiib?= <ootiib@hot.ee>

Newsgroups:

comp.lang.c++

Date:

Wed, 4 Aug 2010 06:05:25 -0700 (PDT)

Message-ID:

<d6c27261-dc79-4610-bf45-f1bd1a3f75ab@i28g2000yqa.googlegroups.com>

On 4 aug, 15:43, Markus Raab <use...@markus-raab.org> wrote:

I created a tiny C++ wrapper around a C-object. The C-object is:
typedef struct {/*...*/} CKeySet;

The C++ wrapper is:
class KeySet
{
public:
        KeySet (CKeySet *k) :ks(k) {} /*takes ownership*/
        ~KeySet (); /*destroys ks*/
        /*... wrapped functions working on ks ...*/
private:
        CKeySet *ks;

};

I have a pointer to CKeySet and want to pass it to a C++ function taking =

reference (KeySet&):

void foo (KeySet &ks);
void bar (CKeySet *orig_ks);

Point of wrapper (KeySet) should be that you get rid of non-wrapped
crap (CKeySet) walking around freely. CKeySet should be implementation
detail after wrapping and all functions that use CKeySet should be in
interface that is only used by KeySet and by nothing else.

How can I call foo from bar without destroying orig_ks?

In what direction you wrap there?

Do I need to create an extra class KeySetNoDestroy without an destructor?

Because of the simplicity of KeySet (its only attribute is a pointer to k=

a cast would also be possible:
void bar(CKeySet *orig_ks)
{
foo(reinterpret_cast<kdb::KeySet&>(orig_ks));

}

This seems not to be very portable. Is it known not to work on some syste=

ms?

Other suggestions?

Get rid of all CKeySet usage with KeySet or delete your unsuccessful
wrapper.
Wrappers that lead to same bad situation as with strings (both char*
and std::string in active usage) should die.