OCaml:使用消息进行断言 [英] OCaml: assert with the message

问题描述

另一个问题:P我不太确定是否应该在此处还是在OCaml邮件列表中发布它，但我会先尝试.

Another question again :P I'm not too sure whether I should post it here or on the OCaml mailing list, but I try SO first.

我喜欢断言语句.但是，我发现错误消息几乎没有用，而没有其他消息(XXX行断言— —很好，但是实际上出了什么问题?). 我认为断言的好例子是pythonic assert x > 0, "X must be greater than zero for the algorithm X to work"，而不好的例子是类似C的assert(x>0).

I like assert statements. However, I find the error messages close to useless without an additional message (assertion violation at line XXX --- well great, but what actually went wrong?). I think the good example of an assertion is a pythonic assert x > 0, "X must be greater than zero for the algorithm X to work" and a bad example is C-like assert(x>0).

我很失望地得知无法将错误消息附加到OCaml =( 我的选择是:

I was quite disappointed to learn that there is no way to attach an error message to an assertion in OCaml =( My options are:

• 编写一个自定义函数，例如vassert =>，但我不会获得魔术行号，而魔术行号只能通过assert关键字来实现
• 使用failwith，但是它更加冗长，而且我认为还存在与自定义函数相同的问题.
• 使用OUnit中的函数，但我不想引入不需要的依赖项.

• Write a custom function, say vassert => but I won't get the magic line numbers which are only possible with the assert keyword
• Use failwith, but it is considerably more verbose, and I think suffers from the same problem as a custom function.
• Use functions from OUnit, but I don't want to introduce unneeded dependency.

其他人也有同样的问题吗?人们使用什么?

Does anyone else have the same problem? What do people use?

推荐答案

有点乏味，但效果很好:

A little bit tedious but works fine:

 assert (if not cond then print_endline "your message"; cond)

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