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

[Lorenzo Donati <lorenzodonatibz@...>]

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