Re: Another option for closing variables

[Hakki Dogusan <hakki@...>]

Hi,

On 12.07.2019 12:36, Lorenzo Donati wrote:
> On 06/07/2019 17:58, Andrew Starks wrote:
> [snip]
>
> I almost feel that /there has to be a better way/ and the current way 
> doesn't feel quite right.
>
> For example, the fact that a /variable/ is marked, but /an object/ is 
> "closed" (using its metamethod) is something smelly. The whole point of 
> RAII is to make very explicit the connection between a resource and the 
> code that handle its release and the time this code is run.
> The current Lua 5.4 mechanism is not so explicit, IMO.

Seconded.

This "variable-value" thing already existed, but it becomes confusing.
IMHO solution should not touch "value/class" metatable.

Maybe something like following is better?
local a = ..
a.__on_scope_exit = function .. end

(Although I'm still thinking that similar to setmetatable, there maybe
setattribute function for variables)


> For that matters, I'm beginning to feel a sort of "defer..end" block 
> could be a better, more general, more explicit, solution.
>
> I love Lua ability to keep the code clean (and clear) in common use 
> cases (although it has its dark corners, e.g. the general for loop 
> syntax - maybe it's me, but I keep forgetting what are those pesky three 
> parameters after "in" keyword <ugh>). I'd like to stay that way.
>
> Cheers!
>
> -- Lorenzo