To use or not to use: deleteLater()

[codeslicer]

Alright thanks a lot, I really understand how this works. One more thing (sorry :P). I heard it's best to dereference a pointer after the object is deleted. If you use deleteLater() is it necessary to do that? Like here:

myObject = new object(this);
 
...
 
myObject->deleteLater();
myObject = 0;

myObject = new object(this);

...

myObject->deleteLater();
myObject = 0;

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Or only use that with delete?

Thanks once again.

[dpimka]

First: You misunderstood the meaning of the word "dereference" Dereferencing means getting a value of the pointer by using a "*" operator. For example:

QObject *obj = new QObject;
qDebug() << *obj; // <-- this is a dereferencing of the "obj" pointer

QObject *obj = new QObject;
qDebug() << *obj; // <-- this is a dereferencing of the "obj" pointer

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Second: Guessing that you asked if it is needed to assign 0 to the pointer after object has been deleted, the answer is: this is handy if your pointer can be potentially used in other places in code (for example if it is a member of some class). In these situations you can check if that object is already deleted. And delete or deleteLater doesn't make difference: Assigning 0 is used only to be able to tell if that ptr still exists or not. Examples:

void myFunction()
{
     MyClass* obj = new MyClass;
     // some action...
     delete obj;
     // obj = 0 <-- doesn't make sense, function will end and no one will ever know about obj as it is a local variable
}

void myFunction()
{
     MyClass* obj = new MyClass;
     // some action...
     delete obj;
     // obj = 0 <-- doesn't make sense, function will end and no one will ever know about obj as it is a local variable
}

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class SomeClass
{
private:
   QObject* m_obj;
 
public:
    void func1()
    {
        m_obj = new QObject;
        // some action
        delete m_obj;
        m_obj = 0;
    }
    void func2()
    {
         // try to use m_obj, but check if it really exists
         if( m_obj )
             // do some stuff
         else
            qDebug() << "oops, m_obj is already deleted";
    }
}

class SomeClass
{
private:
   QObject* m_obj;

public:
    void func1()
    {
        m_obj = new QObject;
        // some action
        delete m_obj;
        m_obj = 0;
    }
    void func2()
    {
         // try to use m_obj, but check if it really exists
         if( m_obj )
             // do some stuff
         else
            qDebug() << "oops, m_obj is already deleted";
    }
}

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