可变长函数

Lua中的可变长函数的参数用 ... 来表示 ( 3个 . )
在函数内部有一个特殊的 内置变量 arg

其格式如下
arg =
{
1,
"Hello",
true,
n = 3
}

-- function  makeVarStr(...) to see print_Table.lua

function printMultiArg(...)
	print("... = " .. makeVarStr(arg))
end


function my_print1(fmt, ... )
	print("=================== Begin my_print1 ===================")
	print("fmt = " .. makeVarStr(fmt))


	print("... = " .. makeVarStr(arg))
	print("=================== End my_print1 ===================\n")
end

function my_print2(fmt, ... )
	print("=================== Begin my_print2 ===================")
	print("fmt = " .. makeVarStr(fmt))

	printMultiArg(arg)
	print("=================== End my_print2 ===================\n")
end

function my_print3(fmt, ... )
	print("=================== Begin my_print3 ===================")
	print("fmt = " .. makeVarStr(fmt))

	printMultiArg(...)
	print("=================== End my_print3 ===================\n")
end



a =1
b = "Hello"
c = true
my_print1("a = ??? , b = ??? , c= ??? ",a,b,c)
my_print2("a = ??? , b = ??? , c= ??? ",a,b,c)
my_print3("a = ??? , b = ??? , c= ??? ",a,b,c)

--[[
=================== Begin my_print1 ===================
fmt = "a = ??? , b = ??? , c= ??? "
... = 
{
   [1] = 1,
   [2] = "Hello",
   [3] = true,
   "n" = 3,
}
=================== End my_print1 ===================

=================== Begin my_print2 ===================
fmt = "a = ??? , b = ??? , c= ??? "
... = 
{
   [1] = 
   {
      [1] = 1,
      [2] = "Hello",
      [3] = true,
      "n" = 3,
   },
   "n" = 1,
}
=================== End my_print2 ===================

=================== Begin my_print3 ===================
fmt = "a = ??? , b = ??? , c= ??? "
... = 
{
   [1] = 1,
   [2] = "Hello",
   [3] = true,
   "n" = 3,
}
=================== End my_print3 ===================


]]

##################################################
Nice Version 1
Use select(n, ...) expression
##################################################

--[[
////////////////////////////////////////////////////////////////////////////////////////////////////// 	        
//  Lua Interpret will assignment 
//    The command line arguments as the internal build-in argument named "arg" 
//       instead of "..." in the function argument list
//
// 	   Variadic Arguments
//
//
////////////////////////////////////////////////////////////////////////////////////////////////////// 	        
--]]

function printAll(fmt, ...)
	print("---------- Begin printAll() ----------\n")
	print("fmt = " .. fmt)
	print("arg = " , ... )
	print()

	--
	-- yield the argument list's  Count
	--
	print("# ... = ", select("#", ...) )

	print("******************************")
	for i=1,select("#", ...) do
		-- Here           : (              )  is a must 
		-- ********************************************************************************************************************
		--                  (              ) ==>  force "select(...)" function return only one argument rathan than multiple arguments
		-- ********************************************************************************************************************
		print("  ",i," = ", (select(i, ...)) )
	end
	print("******************************\n")

	print("---------- End printAll() ----------")
end


printAll("Hello-World : ", "a1", "b2", "c3" , 3.14, true, false, nil , "end"); 

---------- Begin printAll() ----------

fmt = Hello-World :
arg = a1 b2 c3 3.14 true false nil end

# ... = 8

    1        =      a1
    2        =      b2
    3        =      c3
    4        =      3.14
    5        =      true
    6        =      false
    7        =      nil
    8        =      end

---------- End printAll() ----------

##################################################################
Nice Version 2
Use 'arg' internal varible
instead of '...'* <= Variadic arguments
#################################################################

print("--------------------------------------------------")
print("outside arg = ",arg)
print("outside arg.n = ",arg.n)
print("--------------------------------------------------\n")


local newgt = { 
	printAll = function(fmt, ...)
		print("fmt = ",fmt)
		print("inner   arg = ", arg)
		print("inner   arg.n = ", arg.n)

		for i,v in pairs(arg) do
			print("\t",i,v)
		end
		return "Done"
	end

}
setmetatable(newgt, { __index = _G })

-- setfenv(...) is avaliable only in lua5.1
setfenv(1, newgt)



print("                                   [1]   [2]  [3]   [4]    [5]  [6]  [7]")
print("Calling " .. [[printAll("format : %d%c", "a1", "b2", "c3", 3.14, true, nil ,false)]])
print( printAll("format : %d%c", "a1", "b2", "c3", 3.14, true, nil ,false) )

outside arg = table: 00B302A0
outside arg.n = nil

                               [1]   [2]   [3]  [4]   [5]   [6]   [7]

Calling printAll("format : %d%c", "a1", "b2", "c3", 3.14, true, nil ,false)
fmt = format : %d%c
inner arg = table: 00B30138
inner arg.n = 7
1 a1
2 b2
3 c3
4 3.14
5 true
7 false
n 7
Done