Self delete an object in C++ [duplicate]

Question

Possible Duplicate:
C++: Delete this?
Object-Oriented Suicide or delete this;

I wonder if the code below is run safely:

#include <iostream>
using namespace std;

class A
{
public:
    A() {
        cout << "Constructor" << endl;
    }
    ~A() {
        cout << "Destructor" << endl;
    }

    void deleteMe() {
        delete this;
        cout << "I was deleted" << endl;
    }
};

int main()
{
    A *a = new A();
    a->deleteMe();
    cout << "Exit ...";
    return 0;
}

Output is:

Constructor
Destructor
I was deleted
Exit ...

and program exit normally, but are there some memory access violents here?

Answer 1

It's ok to delete this in case no one will use the object after that call. And in case the object was allocated on a heap of course

For example cocos2d-x game engine does so. It uses the same memory management scheme as Objective-C and here is a method of base object:

void CCObject::release(void)
{
    CCAssert(m_uReference > 0, "reference count should greater than 0");
    --m_uReference;

    if (m_uReference == 0)
    {
        delete this;
    }
}

I don't think it's a c++ way of managing memory, but it's possible

Answer 2

It's ok, because you have running simple method. After delete this, all variables and virtual table are clear. Just, analyze this example:

#include <iostream>

class foo
{
public:
    int m_var;
    foo() : m_var(1)  
    {

    }

    void deleteMe()
    {
        std::cout << m_var << "\n";
        delete this;
        std::cout << m_var << "\n"; // this may be crush program, but on my machine print "trash" value, 64362346 - for example
    }

    virtual void bar()
    {
        std::cout << "virtual bar()\n";
    }



  void anotherSimpleMethod()
    {
       std::cout << "anotherSimpleMethod\n";
    }

    void deleteMe2()
    {
        bar();
        delete this;
        anotherSimpleMethod();
        // bar(); // if you uncomment this, program was crashed, because virtual table was deleted
    }
};

int main()
{
    foo * p = new foo();
    p->deleteMe();
    p = new foo();
    p->deleteMe2();
    return 0;
}

I've can't explain more details because it's need some knowledge about storing class and methods in RAM after program is loaded.