Re: Is there a kernel patch for creating local variables programmatically?

[Jay Carlson <nop@...>]

On May 23, 2013, at 7:54 AM, Dirk Laurie wrote:

> 2013/5/18 Dirk Laurie <dirk.laurie@gmail.com>:
>> Often on this list voices have gone up proposing a language addition
>> that would allow one to automate the following process:
>> 
>>    local concat,insert,remove,pack,sort,unpack=
>>       table.concat, table.insert, table.remove, table.pack,
>>       table.sort, table.unpack
>> 
>> by saying Pythonically
>> 
>>    from table import *
>> 
>> or whatever.  Has anybody ever actually produced a kernel patch that
>> implements something of the kind?
> 
> After five days, the answer seems to be "No, because it is impossible."

I would not say it is impossible. I'd say that it has unexpected implications for how modules work: it adds a concept of compile-time dependencies.

There are a couple of possibilities for syntactic sugar with less power:

local (from table) concat,insert,remove,pack,sort,unpack

which is macro-transformed into what you wrote above. Another approach is a destructuring let:

local {concat, insert, remove, pack, sort, unpack} = table

But that looks like it should de-structure {1,2,3} rather than by keyword. In any case destructuring lets are often used for dealing with named, defaulting arguments, so there is a use outside import.

I think those should be pretty easy to implement in tokenf and LuaMacro.