Go语言的创造者写道:
Go doesn't provide assertions. They are undeniably convenient, but our experience has been that programmers use them as a crutch to avoid thinking about proper error handling and reporting. Proper error handling means that servers continue operation after non-fatal errors instead of crashing. Proper error reporting means that errors are direct and to the point, saving the programmer from interpreting a large crash trace. Precise errors are particularly important when the programmer seeing the errors is not familiar with the code.
你对此有什么看法?
如果您所谈论的断言意味着程序抛出然后存在,那么断言可能非常糟糕。这并不是说它们总是错误的使用,它们是一种很容易被误用的结构。他们也有很多更好的选择。这样的事情很容易被称为邪恶。
例如,第三方模块(或任何模块)几乎不应该退出调用程序。这并没有给调用程序的程序员任何控制程序此时应该承担的风险。在许多情况下,数据是如此重要,即使保存损坏的数据也比丢失数据要好。断言可能会迫使您丢失数据。
断言的一些替代方法:
使用调试器,
控制台/数据库/其他日志
异常
其他类型的错误处理
参考:
http://ftp.gnu.org/old-gnu/Manuals/nana-1.14/html_node/nana_3.html
http://www.lenholgate.com/blog/2005/09/assert-is-evil.html
Go不提供断言,并且有很好的理由:http://golang.org/doc/faq#assertions
http://c2.com/cgi/wiki?DoNotUseAssertions
甚至主张assert的人也认为它们应该只用于开发而不是生产:
http://codebetter.com/gregyoung/2007/12/12/asserts-are-not-evil/
http://www.codeproject.com/Articles/6404/Assert-is-your-friend
http://parabellumgames.wordpress.com/using-asserts-for-debugging/
This person says that asserts should be used when the module has potentially corrupted data that persists after an exception is thrown: http://www.advogato.org/article/949.html . This is certainly a reasonable point, however, an external module should never prescribe how important corrupted data is to the calling program (by exiting "for" them). The proper way to handle this is by throwing an exception that makes it clear that the program may now be in an inconsistent state. And since good programs mostly consist of modules (with a little glue code in the main executable), asserts are almost always the wrong thing to do.
我非常不喜欢断言。但我不会说他们是邪恶的。
基本上,assert将做与未检查异常相同的事情,唯一的例外是assert(通常)不应该为最终产品保留。
If you build a safety net for yourself while debugging and building the system why would you deny this safety net for your customer, or your support help desk, or anyone that will get to use the software that you are currently building. Use exceptions exclusively for both asserts and exceptional situations. By creating an appropriate exception hierarchy you will be able to discern very quickly one from the other. Except this time the assert remains in place and can provide valuable information in case of failure that would otherwise be lost.
因此,我完全理解Go的创建者完全删除断言并强迫程序员使用异常来处理这种情况。对此有一个简单的解释,异常只是一种更好的工作机制为什么要坚持使用古老的断言?