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# exception specification

From cppreference.com
< cpp‎ | language

Lists the exceptions that a function might directly or indirectly throw.

### [edit] Syntax

`throw(`typeid, typeid, ...`)` |  | (deprecated)

### [edit] Explanation

If a function is declared with type `T` listed in its exception specification, the function may throw exceptions of that type or a type derived from it.

Incomplete types, pointers or references to incomplete types other than cv `void*`, and rvalue reference types are not allowed in the exception specification. Array and function types, if used, are adjusted to corresponding pointer types.

If the function throws an exception of the type not listed in its exception specification, the function std::unexpected is called. The default function calls std::terminate, but it may be replaced by a user-provided function (via std::set_unexpected) which may call std::terminate or throw an exception. If the exception thrown from std::unexpected is accepted by the exception specification, stack unwinding continues as usual. If it isn't, but std::bad_exception is allowed by the exception specification, std::bad_exception is thrown. Otherwise, std::terminate is called.

### [edit] Example

Run this code

    class X {};
    class Y {};
    class Z : public X {};
    class W {};

    void f() throw(X, Y)
    {
        int n = 0;
        if (n) throw X(); // OK
        if (n) throw Z(); // also OK
        throw W(); // will call std::unexpected()
    }

### [edit] See also

- `noexcept` specifier

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