Re: [proposal] infix function syntax sugar
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- Subject: Re: [proposal] infix function syntax sugar
- From: "Dimiter \"malkia\" Stanev" <malkia@...>
- Date: 2011年12月18日 01:29:40 -0800
And even uglier one, that can handle arithmetic brackets, but reusing
lua's { }
very crude
local function infix(...)
local function eval(t)
local l = t[1]
if type(l) == "table" then l = eval(l) end
for k = 2,#t,2 do
local f, r = t[k], t[k+1]
if type(r) == "table" then r = eval(r) end
l = f(l, r)
end
return l
end
return eval(...)
end
local function add(a,b)
return a + b
end
local function sub(a,b)
return a - b
end
local function mul(a,b)
return a * b
end
local function div(a,b)
return a / b
end
-- Here be { brackets, not (
print( infix{ 12 ,add, 3 ,add, 10 ,sub, { 30 ,mul, 10 } } )
On 12/18/11 1:11 AM, HyperHacker wrote:
2011年12月18日 Dimiter "malkia" Stanev<malkia@gmail.com>:
-- Here is a very poor attempt :)
local function infix(...)
local args = {...}
local nargs = #args
local r = args[1]
for k=2,nargs,2 do
r = args[k](r, args[k+1])
end
return r
end
local function add(a,b)
return a + b
end
print( infix( 12 ,add, 3 ,add, 10 ) )
On 12/17/11 9:23 PM, Xavier Wang wrote:
hi robero and list,
i'm inspired by the post about implement c enum. somebody said the
getflags function shoud return a userdata to implement a contains
function. i think its a good idea, excerpt a details: thus will allocate
memory.
i'm run lua on a embedded system， embedded systemembedded system, nokia
n73 cellphone. my game will lag if i allocate memory in draw function
since the garbage collection. so we avoid any memory in event loop. but
i really miss the contains function, so i think a syntax allow use
function as infix operator will be great.
e.g. if i have a function add(a, b), i can call it with a ｀add｀ b, its
a syntax sugar of add(a,b)
its very simple and can used in many situations, e.g. bitop calls, and
flags contains test.
has anybody agree me? i hope this feature can appear on lua5.3 :)
thanks everybody~
I had done some hacking of metatables to make the following valid syntax:
foo = (3) '<<' (x)
It's still pretty ugly and not terribly efficient, but it works... :p