Re: Lua 5.1+ and variable-argument tables

[Edgar Toernig <froese@...>]

Mark Hamburg wrote:
>
> I rather like that as a way of dealing with the magic name "arg".

:-)  From Sol's changelog:

| sol 0.25 Tue, 14 Nov 2000 18:54:30 +0100 by root
| Parent-Version:      0.24
| Version-Log:         changed vararg syntax: '...' -> 'name[]'
|
| sol 0.24 Tue, 14 Nov 2000 17:38:16 +0100 by root
| Parent-Version:      0.23
| Version-Log:         removed implicit 'self' parameter in function definitions

> Too bad it creates extra heap allocations.

Yeah.  That was the reason for:

| sol 0.116 Thu, 24 Apr 2003 04:27:29 +0200 by froese
| Parent-Version:      0.115
| Version-Log:         new varargs - '...' as multi-value


> This snippet also points to a moderately interesting idiom with respect to
> pcall that isn't entirely easy or at least efficient to implement today.

With the new varargs you can implement it without heap allocations:

local function do2(self, success, ...)
        self:unlock()
        if not success then error(..., 2) end
        return ...
end

function Mutex:do(...)
        self:lock()
	do2(self, pcall(...))
end

Not pretty but reasonable fast.

Ciao, ET.