Re: [ANN] Lua 5.4.0 (alpha) now available

[Paul Ducklin <pducklin@...>]

Add two new keywords. Avoid complex syntactic hacks!



> On 20 Jun 2019, at 10:22, Lorenzo Donati <lorenzodonatibz@tiscali.it> wrote:
> 
>> On 20/06/2019 07:39, Egor Skriptunoff wrote:
>>> On Fri, Jun 14, 2019 at 11:22 PM Viacheslav Usov wrote:
>>> 
>>> This is probably bikeshedding, but:
>>> local (x scoped), (y const), (z const alias) = a, b, c
>>> 
>>> 
>> 
>> This is a nice bikeshedding!
>>> From aesthetic point of view, it looks more pleasant than other possible
>> syntax such as <const>, @const and :const
>> 
> Definitely!
> 
> As far as bikeshedding goes :-) I was one of the proponent of the @const syntax because interfered less with my "internal parser" (angle brackets are either too C++ or they may be confused with relops, especially with long list of attributes).
> 
> This new suggestion is both elegant and readable. "()" means "grouping" anyway in Lua, so no confusion. The "(var_name att_list)" allows both multiple var declarations in a single local statement and also multiple attribute /with no comma inbetween/ (which could confuse reader in long statements with both multiple vars AND multiple attributes.
> 
> This might also elegantly allow parametrized attributes (e.g. for optional type checking)
> 
> Contrived example with hard wrapping (and funny attributes):
> 
> local (x const helpful alias ),
>   (y const alias integer(32) ),
>   (z const final float(64) ),
>   (errmsg const string(256) whatever )
> = mytable, 345, 23.4, myfunc(a,b,c)
> 
> Still quite readable!
> 
> I think I love it! :-)
> 
> I hope this doesn't open the door to some nasty ambiguity (I can't say, I'm no big grammar expert) so that Lua team may possibly consider its adoption!
> 
> The only problem I see is that it can't be applied so easily to global variables or table fields, if ever this was a long term goal.
> 
> Hooray for Viacheslav! :-)
> 
> Cheers!
> 
> -- Lorenzo
> 
> 
>