Re: To-be-closed variables and coroutines
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- Subject: Re: To-be-closed variables and coroutines
- From: Mimmo Mane <pocomane_7a@...>
- Date: 2020年7月31日 19:18:19 +0200
On Fri, Jul 31, 2020 at 2:20 PM Egor Skriptunoff
<egor.skriptunoff@gmail.com> wrote:
> local thread = coroutine.wrap(function()
> local please <close> = setmetatable({}, {__close = function()
> print"coroutine toclose"
> end})
> print"coroutine yields"
> coroutine.yield()
> print"coroutine ends"
> end)
> thread()
> print"program exit"
>
> I don't see "coroutine toclose" printed.
> The Lua manual says we should invoke coroutine.close().
> But we can't :-)
Yes, I think you are right: coroutine.wrap is not usable for now.
However, I would avoid the "Do something at exit" policy. I would
prefer to change the coroutine.wrap implementation to something
__gc/__close -aware [1].
For create/resume instead, I am not fully sure that any automatism is
a good idea. Maybe a lower level design is more flexible: if you
really need, you can use them to build wrappers with automatic
__gc/__close calls [1].
--
[1] Something like:
local function cowrap(f)
local thread = coroutine.create(f)
local closed = false
local function doclose()
if not closed then
coroutine.close(thread)
closed = true
end
end
return setmetatable({},{
__call = function(_,...)
return coroutine.resume(thread,...)
end,
__close=doclose,
__gc=doclose,
})
end