Re: Create a new table based on an already existed table (through Lua or C API)?

[Scott Morgan <blumf@...>]

On 21/01/2021 11:23, 孙世龙 sunshilong wrote:
> Thank you for your detailed explanation.
> 
> The assignment operator does almost the same thing both in Lua and
> Python whereas Python provides deepcopy() to do the aforementioned
> deep copy.
> 
>> As you can see, there's a lot of possible ways to do this, as well as
>> potential issues, such as if there are recursive tables (tables that
> 
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> link to themselves).
>   ^^^^^^^^^^^^^^^^^
> Could you give me a example(i.e recursive tables). I could not find much
> information about it on Google(keyword: Lua recursive tables).
> 
> tab = {};
> tab ={tab};
> I don't think `tab` is a  recursive table indeed.

In that case, you've change the value of tab to a new table containing
the old value of tab.

tab = {}           -- tab points to a new table
tab.child = tab    -- tab.child points to the same table tab points to
tab = {tab}        -- tab now points to another table, which contains
                   -- the value tab used to point to

You might want to see the difference between 'values' and 'variables' here.

A variable points to a value, but is not the value itself.

Seems to be the same issue you had in your other thread[1]. Functions
are not passed variables, they're passed values.



[1] "How to acquire the name of the variables passes to the self-defined
C function which has been successfully set by lua_register()?"