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On 2018-03-20 02:09 AM, Soni "They/Them" L. wrote:



On 2018-03-20 01:57 AM, Dirk Laurie wrote:

2018-03-20 0:38 GMT+02:00 Soni "They/Them" L. <fakedme@gmail.com>:
Let's talk about non-lexical lexical scopings. That is, the ability to undefine variables. 
,,,

   forget a

...

   local a, a, a = 1, 2, 3

This assumes something about implementation of multiple assignment
that Lua does not promise.
...


Those are 3 different locals.

local a, a, a = 1, 2, 3

*is*

local a = 1
local a = 2
local a = 3

(however, the order in which they are assigned is undefined [1])

But, this is different from

a, a, a = 1, 2, 3

Which is undefined, and could be any of:

a = 1
a = 2
a = 3

a = 3
a = 2
a = 1

a = 1
a = 3
a = 2

etc, you get the idea.
[1] - Using non-lexical scoping, local a, a, a = 1, 2, 3 could be expanded to any of: 

local a
local a
local a
do
  forget a
  forget a
  a = 1
end
do
  forget a
  a = 2
end
do
  a = 3
end

-- or

local a
local a
local a
do
  a = 3
end
do
  forget a
  a = 2
end
do
  forget a
  forget a
  a = 1
end

-- etc
They are still 3 locals, declared in order, with the 3 values also declared in order.
You can check this (local a, a, a = 1, 2, 3) with the debug library btw - you'll see 3 separate locals.
You can check the global assignment stuff (a, a, a = 1, 2, 3) with metatables/__newindex. 




I think this sounds neat. What do you think?

`forget a` looks evocative [1]. But `pop(a)` is the more usual word
for this sort of thing.

[1] https://xkcd.com/379/





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