Re: Multiple indexing (was: 'in' keyword today)

[Thomas Jericke <tjericke@...>]

On 04/10/2014 10:04 PM, Sean Conner wrote:
> It was thus said that the Great Thomas Jericke once stated:
> > -----Original Message-----
> > > From: "Sean Conner" <sean@conman.org>
> > >    How about:
> > >
> > >       foo = { a = 1 , b = 2 , c = 3 }
> > >       bar = { x = 'one' , y = 'two' , z = 'three' }
> > >       baz = { one = 'alpha' , two = 'beta' , three = 'gamma' }
> > >
> > >       a,b,c in foo = x,y,z in bar in baz
> > Depends on the order of the in operarator, IMO it should be right to left:
> >
> > foo["a", "b", "x"] = baz["bar"]["x", "y", "z"]
> >
> > As  baz["bar"] is nil, you will get:
> >
> > attempt to index field bar (a nil value)I think what you wanted to write is:
> >
> > a,b,c in foo =  baz[x,y,z in bar]
>    Interesting.  Because in my mind, I was parsing it as
>
> 	a,b,c in foo = (x,y,z in bar) in baz
>
>    (left to right) That is:
>
> 	foo.a = baz[bar.x]
> 	foo.b = baz[bar.y]
> 	foo.c = baz[bar.z]
>
>    I'm not saying I'm right or you are wrong, just how I would interpet it.
>
>    -spc (Anybody?  Anybody?  Bueller?  Bueller?)
You have a mistake in you inner interpreter right there

I wrote:
a,b,c in table -> table["a", "b", "c"]

If you want to expand left to right you get

a,b,c in foo = (x,y,z in bar) in baz

foo["a", "b", "c"] = (bar["x, y, z"]) in bat -- syntax error: name 
expected near "(bar["x, y, z"])"

The statements in front of the in must be names not expressions, if you 
start to mix them the code will get ambiguous. Example:

local t = {}
local table = { t = "lala" }
table[t] = "dada"

local test = t in table
print (test) -- lala or dada ?

--
Thomas