Re: private constructor and new operator overloading.

From:

"Paolo Maldini" <jifang1218@msn.com>

Newsgroups:

comp.lang.c++

Date:

Sat, 12 May 2007 00:03:46 +0800

Message-ID:

<f226qn$3sp$1@news.cn99.com>

you need to write a new static member function to instead of the operator
new.

for instance:
class MyClass {
public:
static MyClass* New();
// using keyword "protected" means it can be derived.
// using keyword "private" means it cannot be derived any more.
protected:
MyClass();
};

int main() {
....
MyClass* pMyClass = MyClass::New();
....
delete pMyClass;
....
}

"siddhu" <siddharth.sng@gmail.com>
??????:1178898305.430200.284730@h2g2000hsg.googlegroups.com...

On May 11, 11:27 am, siddhu <siddharth....@gmail.com> wrote:
A correction in the code snippet..

Dear Experts,

I want to make a class whose objects can be created only on heap.
I used the following approach.

class ss
{
        ss(){}
        public:
        void* operator new(size_t sz)
                {
                        cout<<"in new"<<endl;
                        return malloc(sz); //return new char[sz];

//sorry..... my
mistake

                }
             void operator delete(void* m)
                {
                        free(m);
                }

};

int main()
{

  ss* s = new ss;
return 0;

}

But when I do
ss* s = new ss;
compiler complains that constructor ss::ss() is private.
As operator new function is member of class so compiler should not
complain because operator new function can call the default
constructor even if it is private.
I am surprised and confused.
Suggestions would be of great help.

Regards,
Siddharth