ZDoom

[quote=RicardoLuis0 post_id=1242573 time=1688667978 user_id=27040]
[quote=phantombeta post_id=1242545 time=1688610412 user_id=8451]
[c]x !is y[/c] or [c]x is not y[/c]
[/quote]
both of those would require significant changes, due to how zscript parses operations ([c]isnot[/c] wouldn't require them -- it follow the same rules as any other operation like [c]is[/c])
[/quote]

Actually, they wouldn't require much of a change at all. Have you seen how ZScript does 'static const'?
All it does is combine both tokens to one before passing it to the grammar parser, so you could do the same with '!is'.

I've wanted this also. No functional difference, just code that is slightly easier to read/write

[quote=phantombeta post_id=1242545 time=1688610412 user_id=8451]
[c]x !is y[/c] or [c]x is not y[/c]
[/quote]
both of those would require significant changes, due to how zscript parses operations ([c]isnot[/c] wouldn't require them -- it follow the same rules as any other operation like [c]is[/c])

I personally don't see any reason not to have this, if implemented correctly it'd just be syntactic sugar for [c]!(x is y)[/c] anyway.
IMO [c]x !is y[/c] or [c]x is not y[/c] would be better, though.

I'd be willing to implement this myself if it gets a "yes"

if (mo isnot "MyCoolActor")

if (!(mo is "MyCoolActor"))

It's just some syntax sugar, because [code]if (mo isnot "MyCoolActor")[/code] looks better than [code]if (!(mo is "MyCoolActor"))[/code] Would make it compliment to == and !=