Re: level argument for assert

[Philipp Janda <siffiejoe@...>]

Am 02.01.2013 21:00, schrieb Thijs Schreijer:
> > Another caveat is that some functions in os and many functions in io
> > return nil,msg,errno in case of error, and this would mess with the level
> > argument ...
>
> That is indeed a nasty one. But still very annoying that there is no level on an assert call. Any ideas on how to add such a thing without breaking anything?

AFAIK there is no function (in the standard library) returning more than 
three values in the error case, so `assert( ok, msg, _, lvl )` probably 
would work. But I believe the current protocol is: nil, error_msg, + 
whatever_is_useful, so it will likely break for some third party code. 
You could always add separate functions for different stack levels 
(assert, assert1, assert2, assert3, ...). My favorite would be a 
func-table with a memoizing __index: assert( bla() ), assert[2]( blub() 
) ), etc., but this will probably break some unit testing frameworks (if 
they replace assert themselves).

> Thijs

Philipp