Re: Why does not the finalizer been called at the end of the first or second for loop?

[孙世龙 sunshilong <sunshilong369@...>]

>The loop keeps a reference of the value passed to 'pairs' which disappears when the goto statement executes.


^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Not after the statement executed?

On Wed, Oct 21, 2020 at 11:51 AM Gé Weijers <ge@weijers.org> wrote:
>
>
>
> On Tue, Oct 20, 2020, 19:16 孙世龙 sunshilong <sunshilong369@gmail.com> wrote:
>>
>> >The for loop will keep
>> >the 'list' value on the stack until you exit the loop. So "list = v"
>> >does not make the old value of 'list' unreachable, and collectgarbage
>> >cannot collect the value yet.
>> You could see that the old value of 'list' is freed in later loop
>> indeed(there are outputs that contain "gc:").
>> Here are the outputs:
>> key= 1 value= 5
>> key= link value= table: 0x55b1c39c0630
>> ===========
>> key= 1 value= 4
>> key= link value= table: 0x55b1c39c8e30
>> ===========
>> gc: 5 nil                                               ---Attention
>> here! It's freed at here, not at the previous loop.
>
>
> This is the first time collectgarbage is called when the program does not reference the table with key 5 anymore, so the finalizer can be called. The call to __gc is done once the collector determines that the table is no longer referenced.
> The loop keeps a reference of the value passed to 'pairs' which disappears when the goto statement executes.
>
>
>> key= 1 value= 3
>> key= link value= table: 0x55b1c39c85e0
>> ===========
>> gc: 4 nil
>> key= 1 value= 2
>> key= link value= table: 0x55b1c39c8860
>> ===========
>> gc: 3 nil
>> key= 1 value= 1
>> gc: 2 nil
>> gc: 1 nil
>>
>> On Tue, Oct 20, 2020 at 10:30 PM Gé Weijers <ge@weijers.org> wrote:
>> >
>> > On Mon, Oct 19, 2020 at 1:33 AM 孙世龙 sunshilong <sunshilong369@gmail.com> wrote:
>> > > --Question:
>> > > --                Why does not the finalizer been called here after
>> > > "list = v" has been invoked?
>> > > --                For the former variable "list" is still referenced
>> > > by "k,v in pairs(list)"?
>> > > --                If the guess aforementioned is right, why does not
>> >
>> > you call 'collectgarbage' in the for loop. "pairs" returns the
>> > function "next", its parameter (list), and nil. The for loop will keep
>> > the 'list' value on the stack until you exit the loop. So "list = v"
>> > does not make the old value of 'list' unreachable, and collectgarbage
>> > cannot collect the value yet. All of this is easy to figure out from
>> > the definition of "pairs" and the description of the for loop in the
>> > Lua manual.
>> >
>> > Gé
>> >
>> >
>> >
>> >
>> > --
>> > Gé