Is a `this != &rhs` Check Necessary in a Move Assignment Operator?

Move Assignment Operator and this != &rhs

In the standard assignment operator for a class, it's common practice to include a this != &rhs check to avoid modifying the invoking object when assigning to itself. However, is this check necessary in the move assignment operator?

Answer:

Opinions vary on whether the this != &rhs check is needed in the move assignment operator. Some argue that it is a good practice to always include it, while others believe it is unnecessary and potentially harmful.

Rationale:

• Reason to include the check: It ensures that the object being assigned is not the invoking object itself, preventing self-assignment.
• Reason to omit the check: In the move assignment operator, the invoking object is, by definition, not a reference to the right-hand side (RHS) object. Therefore, the this != &rhs check is inherently true and unnecessary. Moreover, if the RHS and LHS are accidentally swapped, the check will fail, causing undefined behavior.

Conclusion:

Ultimately, whether or not to include the this != &rhs check in the move assignment operator is a matter of personal preference and context. It is not required by the C standard, but some developers may choose to include it for added safety or to avoid unintentional self-assignment.

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