Can a Common Function Replace Both the Copy Constructor and Copy Assignment Operator?

Writing a Common Function for Copy Constructor and Copy Assignment Operator

In programming, both the copy constructor and the copy assignment operator often share a significant portion of their implementation. This similarity prompts the question: can we merge their functionality into a single common function?

The Common Function Approach

Yes, it's possible to create a common function that handles both the copy constructor and the copy assignment operator. Here's how:

Option 1: Explicit Operator= Invocation from Copy Constructor (Discouraged)

MyClass(const MyClass& other)
{
    operator=(other);
}

However, this approach isn't recommended because:

• It raises issues with object initialization and self-assignment.
• It introduces unnecessary member initialization steps, even if reassignment is intended.

Option 2: Copy-and-Swap Idiom

MyClass& operator=(const MyClass& other)
{
    MyClass tmp(other);
    swap(tmp);
    return *this;
}

The copy-and-swap idiom offers several advantages:

• Self-assignment safety.
• Strong exception safety, ensuring the old state is preserved if an exception occurs during assignment.
• Reduced code complexity, as resource allocation and cleanup are handled by the swap function.

Swap Function Considerations

It's crucial to use a "true" swap function that directly exchanges the internals without relying on the copy constructor or copy assignment operator. Memberwise swaps or using std::swap with basic types and pointers are typically appropriate.

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