C++核心准则E.31:正确排列catch子句

E.31: Properly order your catch-clauses

E.31:正确排列catch子句

Reason（原因）

catch-clauses are evaluated in the order they appear and one clause can hide another.

catch子句按照它们表示的次序行，一个子句出发之后，其他子句不再执行。

Example（示例）

void f()
{
    // ...
    try {
            // ...
    }
    catch (Base& b) { /* ... */ }
    catch (Derived& d) { /* ... */ }
    catch (...) { /* ... */ }
    catch (std::exception& e) { /* ... */ }
}

If Derivedis derived from Base the Derived-handler will never be invoked. The "catch everything" handler ensured that the std::exception-handler will never be invoked.

如果Deriveds是Base的派生类，捕捉派生类的处理永远不会执行。捕捉所有异常的处理会导致捕捉std::exception的处理程序永远不会执行。

Enforcement（实施建议）

Flag all "hiding handlers".

标记所有被隐藏的异常处理程序。

原文链接

https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#e31-properly-order-your-catch-clauses