Should Constructors Throw Exceptions?

Should Constructors Throw Exceptions?

The practice of throwing exceptions from constructors has sparked debate among programmers. This article explores the topic, examining the appropriateness of this approach from a design perspective.

In situations where a constructor requires proper initialization and its failure renders the object unusable, exceptions become a valuable tool. For instance, the provided code snippet demonstrates a C class that wraps a POSIX mutex. Upon construction, it initializes the internal mutex and throws an exception if the initialization fails.

This design choice ensures that the mutex object is guaranteed to be in a valid state before allowing its use. By throwing an exception, the constructor explicitly communicates its inability to create a functional object to the calling code. This prevents the creation of invalid objects, preserving the program's integrity and preventing potential data corruption.

While alternative approaches, such as creating an init() method that returns a Boolean value, are viable, they introduce the potential for user error. Developers may forget to call init() or mistakenly assume the object's validity based on a successful method call. Exceptions eliminate this possibility, enforcing proper object initialization at the point of creation.

Therefore, from a design perspective, throwing exceptions from constructors is a valid approach when the proper initialization of an object is crucial to ensure its functionality and data integrity. It provides a clear mechanism for communicating construction failures and preventing the creation of invalid objects.

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