[Python-ideas] Runtime assertion with no overhead when not active

[Eloi Gaudry]

On Mon, 2018-05-07 at 10:52 -0700, Guido van Rossum wrote:
> On Mon, May 7, 2018 at 6:24 AM, Serhiy Storchaka <storchaka at gmail.com
> > wrote:
> > I just don't understand why you need a new keyword for writing
> > runtime checks.
> 
> Oh, that's pretty clear. The OP wants to be able to turn these checks
> off with some flag he can set/clear at runtime, and when it's off he
> doesn't want to incur the overhead of evaluating the check. The
> assert statement has the latter property, but you have to use -O to
> turn it off. He basically wants a macro so that
> 
>   runtime_assert(<expr>)
> 
> expands to
> 
>   if <controlling flag> and (<expr>):
>       raise AssertionError
> 
> In Lisp this would be easy. :-)

and he already has a diff ready for review if needed (basically very
similar to the current 'assert' implementation :)