To STL or not to STL, that is the question...

[Paul McKenzie]

Well now that I think about it:

I know that it is safe to directly delete an object that is derived from a class that does not have a virtual destructor. Therefore, make me amend what I've been saying:

Since my example derived from string_vector, and if string_vector has a virtual destructor, and you delete directly a "string_vector" object or pointer, you are fine. This is not disputed, but I wasn't thinking this at the time. Sorry for the wrong information.

Now, the rub is how far up the coder will declare their pointer in the hierarchy: if the coder were to go up one more above the hierarchy and declared a pointer to vector<string> and used it polymorphically, then they would be in trouble.

int main()
{
   std::vector<std::string> *pMyVect;
   if ( do_some_customizations )
      pMyVect = new MyCustomizedStringVector;
   else
     pMyVect = new AnotherCustomizedStringVector;
//...
   delete pMyVect;  // trouble
}

So you still need to post a warning as to how far up the hierarchy someone can use your class polymorphically -- right now, they can stop at string_vector, but go no further up the branch when a pointer is declared.

AvDav's most recent post shows the dangers of deriving from a class that does not have a virtual destructor, and how easily it can be erroneously used in a program without any great programming effort.

Regards,

Paul McKenzie