The Perils of "Throw" in Function Signatures

While it may be tempting to incorporate the "throw" keyword in a function signature to explicitly declare the potential for exceptions, this practice is strongly discouraged. Despite its seemingly straightforward purpose, there are several technical reasons why this approach is considered a poor choice.

Compiler Limitations

One significant issue arises from the compiler's inability to enforce exception specifications declared in function signatures. As a result, the compiler cannot verify that the function will indeed throw the specified exception. This leads to potentially misleading signatures, as the function might actually throw a different exception or none at all.

Runtime Ineffectiveness

Exception specifications are checked during runtime, imposing a performance overhead. This is particularly undesirable when compared to modern exception handling mechanisms that perform these checks more efficiently at compile time.

Inconsistent Implementation

Exception specifications have varying levels of support across different compilers. For example, MSVC largely ignores exception specifications, except for the special case of "throw()", which is interpreted as a guarantee that no exception will be thrown. This inconsistency creates platform-specific issues and complicates portability.

Alternatives to Exception Specifications

Given the drawbacks of using "throw" in function signatures, it is recommended to adopt alternative approaches for exception handling. These include:

• Using RAII (Resource Acquisition Is Initialization) techniques to manage resources and handle potential errors
• Employing exception classes to clearly define and handle specific exception scenarios
• Using structured exception handling mechanisms that provide compile-time checks and more efficient exception handling