When C++11 introduced auto, it opened up a whole range of useful techniques and improved the life of C++ developers in a variety of ways. There’s no shortage of simple examples and tutorials teaching how to start using auto, but as is often the case, many of these well intentioned examples have left readers with an incomplete picture of how to use auto effectively and in some cases have resulted in poor habits becoming common practice. Since auto essentially hides away some of the details of how objects are created, there is a risk that developers don’t think as carefully about what is actually taking place. This article aims to arm the reader with information often omitted so that common pitfalls can be avoided.

Read more

Let’s explore your understanding of member function overloading. For a given class, how many different non-template overloads can you define for a given function where the function takes no arguments? Putting aside exception specifications (since allowing them would make the answer to this essentially infinite), let’s make this a multiple choice, pick your answer from: 1, 2, 4 or 8. I’ll even provide a clue that the return types of the functions don’t matter. For extra points, how many of the function overloads are likely to be useful?

Read more

I recently came across an interesting use of std::move which looked something like the following:

void MyObject::processItems()
{
    std::vector<int> items(std::move(m_items));
    for (auto item : items)
    {
        // Do things which may add new items to m_items
    }
}

The intent of the code was that every time the member function processItems() was called, it would perform some operation on each item held in the member variable m_items. Each processed item should be removed from m_items. The operation to be performed might generate new items which would be added to m_items, so care had to be taken about how to iterate over the set of items.

To ensure robust iteration over the items to be processed, the code transfers the contents of m_items to a local object and then iterates over that local object. Thus, if new items are created during processing, they would be added to m_items and the container being iterated over (items) would not be affected. All good, right? Well, probably yes, but by no means is it guaranteed.

Read more