c++ - 来自异常声明的派生对象类型是否意外？

Question

在C++中，在异常声明说明符中，如果我声明一个基类，然后抛出一个派生类，是不是意外异常？

Answer 1

In C++, in the exception declaration specifier, if I declare a base class and then throw a derived class, is that an unexpected exception?

没有。这是允许的。

引用:C++03 15.4 异常规范

第 6 段:

An exception-specification can include the same type more than once and can include classes that are related by inheritance, even though doing so is redundant. An exception-specification can also include the class std::bad_exception (18.6.2.1).

中有一个相关的例子第 8 段:

[Example:
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    <------- Example of the exact scenario you posted
    throw W(); // will call unexpected()
}
—end example]

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请注意，异常规范被视为失败的实验，大多数编译器都没有正确实现它们。所以避免(而不是不)使用它们。