Re: behaviour of assert on non-string errors

[Justin Cormack <justin@...>]

On Sat, Jan 18, 2014 at 9:59 AM, Dirk Laurie <dirk.laurie@gmail.com> wrote:
> 2014/1/18 Peng Zhicheng <pengzhicheng1986@gmail.com>:
>
>> IMHO, `assert' and `error' have quite different semantics and use cases.
>
>> So, it is quite reasonable for me that `assert' only accept a string
>> message, since it is to give the (interactive session) user some clue
>> about what went wrong, instead of to give `pcall' the `error object' to
>> examine (and maybe to retry or recover) in a programamtic way,
>> in which case `error' should be used.
>
> +1
>

But but, that means you have to rewrite your code to only use string
errors not error tables? The whole point is that it fails to give you
any clue as it just gives an error about the error not being a string,
when the error has a perfectly good __tostring method that will give
you a helpful result if called.

Non string error returns are incredibly useful in making a nice
interface. It is exactly the interactive case where the fact assert
does not call __tostring is most annoying.

Justin