notthrow

nothrow is a compiler directive or attribute used in some programming languages, most notably C++ and C#, to indicate that a particular function or method is guaranteed not to throw any exceptions. This declaration allows the compiler to perform certain optimizations, as it doesn't need to generate the exception handling code or stack unwinding mechanisms for that specific function.

In C++, the `noexcept` specifier serves this purpose. When applied to a function, `noexcept(true)` (or simply `noexcept`) explicitly states that the function will not throw exceptions. Conversely, `noexcept(false)` indicates that exceptions may be thrown. If a `noexcept` function is called and an exception is thrown, the program will typically terminate immediately. This feature is crucial for performance-critical code, especially in destructors and move constructors, where exceptions can lead to undefined behavior.

Similarly, C# has the `throw` keyword which is used to explicitly throw an exception. However, it does not have a direct equivalent to C++'s `noexcept` attribute for compiler optimization. Instead, developers rely on careful design and error handling practices to manage exceptions. The absence of explicit `noexcept` in C# means the runtime always accounts for potential exceptions, which can lead to a slight performance overhead compared to languages that offer explicit guarantees. The concept of "not throwing" in C# is more of a programming convention and a goal achieved through disciplined coding rather than a compiler-level optimization directive.