Re: Creating closures (or not)

[Eike Decker <zet23t@...>]

2010/7/13 Doug Currie <doug.currie@gmail.com>:
>
> On Jul 13, 2010, at 8:04 AM, Roberto Ierusalimschy wrote:
>
>>> My guess is that they would only be pooled if they share the same prototype,
>>> and do not use any upvalues, such as:
>>>
>>> t = {}
>>> for i = 1, 10 do
>>>  t[i] = function() end
>>> end
>>
>> They may be reused even with upvalues, as long as they have the same
>> upvalues; each prototype caches the last closure created with it.
>
> So, I suppose this code creates one closure...
>
> t = {}
> local a
> for i = 1, 10 do
>  a = i
>  t[i] = function() a = a + 1; return a end
> end
>
> and this code 10 closures...
>
> t = {}
> for i = 1, 10 do
>  local a
>  a = i
>  t[i] = function() a = a + 1; return a end
> end
>
> Another argument against local by default!
>
> e
>
>

Your code will not work as you expect. All 10 functions share the same
variable and will operate on the same values. If you want to have
different variables, there is no way around either objects or
closures. Why are you afraid of "new" closures?

Greetings,
Eike