Re: from: Lua Module Function Critiqued

[Andrew Starks <andrew.starks@...>]

On Mon, Oct 7, 2013 at 11:51 AM, Dirk Laurie <dirk.laurie@gmail.com> wrote:
> 2013/10/7 Andrew Starks <andrew.starks@trms.com>:
>
>> PS: (function print("hello") end )() is a good way to encapsulate
>> something within a scope, but it ends up leading to a bunch of ";" and
>> is more verbose than using "do ... end".
>>
>> do
>>    print("hello")
>> end
>
> The two techniques are not equivalent.
>
> A do..end block limits the scope of the local variables, true,
> but there must be enough slots left to accommodate them. Whereas
> immediate execution of an anonymous function allows you to start
> from scratch: locals outside become upvalues.
>
> You can demonstrate the difference thus:
>
> Make 20 copies of a line with 10 copies of 'local x ' on it.
> After that,
>
>      do local y print(x==y) end
>
> gives a 'too many local variables' error, whereas
>
>     (function () local y  print(x==y) end)()
>
> works.
>


I did not know that, although I've read "precious local" and other
references to the limited nature of them.

Thanks, Dirk!

-Andrew