我一直相信,如果一个方法可以抛出异常,那么不使用有意义的try块来保护这个调用就是鲁莽的。

我刚刚发布了‘你应该总是包装调用,可以抛出try, catch块。,结果被告知这是一个“非常糟糕的建议”——我想知道为什么。


当前回答

As Mitch and others stated, you shouldn't catch an exception that you do not plan on handling in some way. You should consider how the application is going to systematically handle exceptions when you are designing it. This usually leads to having layers of error handling based on the abstractions - for example, you handle all SQL-related errors in your data access code so that the part of the application that is interacting with domain objects is not exposed to the fact that there is a DB under the hood somewhere.

除了“在任何地方捕获所有东西”的味道之外,还有一些相关的代码味道是您一定要避免的。

"catch, log, rethrow": if you want scoped based logging, then write a class that emits a log statement in its destructor when the stack is unrolling due to an exception (ala std::uncaught_exception()). All that you need to do is declare a logging instance in the scope that you are interested in and, voila, you have logging and no unnecessary try/catch logic. "catch, throw translated": this usually points to an abstraction problem. Unless you are implementing a federated solution where you are translating several specific exceptions into one more generic one, you probably have an unnecessary layer of abstraction... and don't say that "I might need it tomorrow". "catch, cleanup, rethrow": this is one of my pet-peeves. If you see a lot of this, then you should apply Resource Acquisition is Initialization techniques and place the cleanup portion in the destructor of a janitor object instance.

我认为充斥着try/catch块的代码是代码评审和重构的好目标。它表明要么异常处理没有被很好地理解,要么代码已经变成了无用的,急需重构。

其他回答

As Mitch and others stated, you shouldn't catch an exception that you do not plan on handling in some way. You should consider how the application is going to systematically handle exceptions when you are designing it. This usually leads to having layers of error handling based on the abstractions - for example, you handle all SQL-related errors in your data access code so that the part of the application that is interacting with domain objects is not exposed to the fact that there is a DB under the hood somewhere.

除了“在任何地方捕获所有东西”的味道之外,还有一些相关的代码味道是您一定要避免的。

"catch, log, rethrow": if you want scoped based logging, then write a class that emits a log statement in its destructor when the stack is unrolling due to an exception (ala std::uncaught_exception()). All that you need to do is declare a logging instance in the scope that you are interested in and, voila, you have logging and no unnecessary try/catch logic. "catch, throw translated": this usually points to an abstraction problem. Unless you are implementing a federated solution where you are translating several specific exceptions into one more generic one, you probably have an unnecessary layer of abstraction... and don't say that "I might need it tomorrow". "catch, cleanup, rethrow": this is one of my pet-peeves. If you see a lot of this, then you should apply Resource Acquisition is Initialization techniques and place the cleanup portion in the destructor of a janitor object instance.

我认为充斥着try/catch块的代码是代码评审和重构的好目标。它表明要么异常处理没有被很好地理解,要么代码已经变成了无用的,急需重构。

我想在这个讨论中补充一点,自从c++ 11以来,它确实很有意义,只要每个catch块重新抛出异常,直到它可以/应该被处理为止。通过这种方式可以生成反向跟踪。因此,我认为前面的观点在某种程度上已经过时了。

使用std::nested_exception和std::throw_with_nested

在这里和这里的StackOverflow描述了如何实现这一点。

由于可以对任何派生异常类执行此操作,因此可以向这样的回溯添加大量信息! 你也可以看看我在GitHub上的MWE,在那里回溯看起来是这样的:

Library API: Exception caught in function 'api_function'
Backtrace:
~/Git/mwe-cpp-exception/src/detail/Library.cpp:17 : library_function failed
~/Git/mwe-cpp-exception/src/detail/Library.cpp:13 : could not open file "nonexistent.txt"

Herb Sutter在这里写过这个问题。绝对值得一读。 摘要:

"Writing exception-safe code is fundamentally about writing 'try' and 'catch' in the correct places." Discuss. Put bluntly, that statement reflects a fundamental misunderstanding of exception safety. Exceptions are just another form of error reporting, and we certainly know that writing error-safe code is not just about where to check return codes and handle error conditions. Actually, it turns out that exception safety is rarely about writing 'try' and 'catch' -- and the more rarely the better. Also, never forget that exception safety affects a piece of code's design; it is never just an afterthought that can be retrofitted with a few extra catch statements as if for seasoning.

我听到过的最好的建议是,您应该只在可以对异常条件采取措施的情况下捕获异常,而“捕获、记录和释放”并不是一个好策略(如果在库中偶尔不可避免的话)。

您不需要在try-catch中掩盖代码的每一部分。try-catch块的主要用途是错误处理和获取程序中的错误/异常。try-catch -的用法

您可以在想要处理异常的地方使用此块,或者简单地说编写的代码块可能抛出异常。 如果你想在对象使用后立即释放它们,你可以使用try-catch块。