Re: Added `continue` keyword to Lua 5.4 [code review requested].

[Sean Conner <sean@...>]

It was thus said that the Great GoldenKnightFly once stated:
> `continue` is useful if you're working with input checking. For example
> you're checking user input through stdin, you want to check if it's valid
> if not do the input again.
> 
>     while true do
>       io.write "Please input an ascii code: "
>       local input = io.read()
> 
>       if not input:match "^%d+$" then
>         print "Not a number"
>         continue
>       end
> 
>       local ok,ch = pcall(string.char,tonumber(input))
>       if not ok and ch then
>         print("Failed to parse code:",ch)
>         continue
>       end
> 
>       print("Char: "..ch)
>       break
>     end
>     end

  I get around the lack of a continue in Lua by using the fact that Lua
supports tail-call optimization.  I would recode the above to be:

	function foo()
	  io.write "Please input an ASCII code: "
	  local input = io.read()
	  
	  if not input:match "^%d+$" then
	    print "Not a number"
	    return foo()
	  end

	  local ok,ch = pcall(string.char,tonumber(input))
	  if not okay and ch then
	    print("Failed to parse code: ",ch)
	    return foo()
	  end

	  print("Char: " .. ch)
	end

	foo()

  This works across Lua versions 5.1 and higher.

  -spc