README.md

Unofficial repositary of vararg

vararg is a Lua library for manipulation of variable arguements (vararg) of functions. These functions basically allow you to do things with vararg that cannot be efficiently done in pure Lua but can be easily done through the C API.

Actually, the main motivation for this library was the 'pack' function, which is an elegant alternative for the possible new standard function 'table.pack' and the praised 'apairs'. Also 'pack' allows an interesting implementaiton of tuples in pure Lua.

Changes since official vararg v1.1

• C version supports Lua 5.2/5.3
• Fix bugs on Lua version. Now it pass all tests.
• Lua and C version are fully compatible (excapt error messages).
• Use call metamethod as alias for pack method (vararg(...) is same as vararg.pack(...))
• Add va.count function
• Add va.at function

pack

args = pack(...)

vararg	lua
args()	...
args("#")	select("#", ...)
args(i)	(select(i, ...))
args(i, j)	unpack({...}, i, j)
for i,v in args do	for i,v in ipairs{...} do

vararg methods

Assume this shortcuts

tremove = function(t, i)    table.remove(t, i)    return t end
tinsert = function(t, i, v) table.insert(t, i, v) return t end
tset    = function(t, i, v) t[i] = v              return t end
tappend = function(t, v)    t[#t+1] = v           return t end

vararg	lua
count(...)	select("#", ...)
range(i, j, ...)	unpack({...}, i, j)
at(i, ...)	range(i, i, ...)
remove(i, ...)	unpack(tremove({...},i),1,count(...)-1)
insert(v, i, ...)	unpack(tinsert({...},i,v),1,count(...)+1)
replace(v, i, ...)	unpack(tset({...}, i, v) t,1,count(...))
append(v, ...)	unpack(tappend({...},v),1,count(...)+1)
map(f, ...)	t={} for i, arg in pack(...) do t[i]=f(arg) end unpack(t)
concat(f1,f2,...)	return all the values returned by functions 'f1,f2,...'

Examples

Implement basic bind function

function bind(f, ...)
  local args = va(...)
  return function(...)
    return f(va.concat(args, va(...))
  end
end
debug_print = bint(print, '[debug]')
debug_print('hello')

Pack in to array returned values from several functions

function f(...) return ... end

t = {va.concat(
  va(f(1,2,3)),
  va(f(4,5,6)),
)}

-- t = {1,2,3,4,5,6}

Write to stdout but convert values to string.

function write(...)
  return io.write(va.map(tostring, ...))
end

local hello = setmetatable({},{__tostring = function() return "Hello" end})

write(hello, " world!!! ", nil, '\n')

Parse IPv4 address

local n1,n2,n3,n4 = va.map(tonumber, string.match(ip, "^(%d+)%.(%d+)%.(%d+)%.(%d+)$"))
-- test nX as number