Re: Object system

[Raffaele Salmaso <raffaele@...>]

David Given wrote:
> Incidentally, it occurs to me that you should be able to optimise things by 
> making __call pregenerate all the closures. It ought to be something along the 
> lines of:
>
> 		__call = function(self, ...)
> 			tmp = {}
> 			setmetatable(tmp, klass)
> 			for i, j in pairs(super) do
> 				tmp[i] = function (...)
> 					return j(tmp, unpack(arg))
> 				end
> 			end
> 			if self.init then
> 				self.init(tmp, unpack(arg))
> 			end
> 			return tmp
> 		end
>
> ...although that doesn't take in to account object inheritence.
>
> Would that work? If so, would it speed things up any?
I don't think it would works. It would works only for one level of 
inheritance.

I've modified the class() function to add a cache for the methods, and 
tested on my machine (apple ibook G3 800 640Mb) with lua 5.0.2

without cache
10:32:47 Mar Dic 07 raf@ice ~
$ time lua klass.lua

real    0m1.877s
user    0m1.420s
sys     0m0.040s
10:33:57 Mar Dic 07 raf@ice ~
$ time lua klass.lua

real    0m1.912s
user    0m1.450s
sys     0m0.040s
10:34:00 Mar Dic 07 raf@ice ~
$ time lua klass.lua

real    0m1.924s
user    0m1.480s
sys     0m0.040s

with cache
10:34:03 Mar Dic 07 raf@ice ~
$ time lua klass.lua

real    0m1.377s
user    0m1.030s
sys     0m0.050s
10:34:46 Mar Dic 07 raf@ice ~
$ time lua klass.lua

real    0m1.453s
user    0m1.060s
sys     0m0.030s
10:34:48 Mar Dic 07 raf@ice ~
$ time lua klass.lua

real    0m1.431s
user    0m1.070s
sys     0m0.030s

So with a cache is really faster. But you trade speed with (memory) space.

Attacched are the two version, bugs free (I hope!), and a little test.

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--
-- Copyright (C) 2004, Salmaso Raffaele <raffaele@salmaso.org>
--
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions are met:
--
--  1. Redistributions of source code must retain the above copyright notice,
--     this list of conditions and the following disclaimer.
--  2. Redistributions in binary form must reproduce the above copyright
--     notice, this list of conditions and the following disclaimer in the
--     documentation and/or other materials provided with the distribution.
--  3. If the binary program depends on a modified version of this package,
--     you are encouraged to publicly release the modified version of this
--     package.
--
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
-- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
-- IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
-- ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
-- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
-- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
-- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
-- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
-- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
-- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
-- POSSIBILITY OF SUCH DAMAGE.

-- operator overloading
-- __add +
-- __mul *
-- __sub -
-- __div /
-- __le <=
-- __lt <
-- __eq ==
-- __tostring
-- __call ()
-- __index []
-- __newindex
-- __pow ^
-- __unm
-- __concat ..

function class_nocache(super)
    -- create a new class description
    local klass = {}
    -- set the superclass (for object inheritance)
    setmetatable(klass, {
        __index = super,
        __call = function(self, ...)
            local tmp = {}
            setmetatable(tmp, klass)
            if self.init then
                self.init(tmp, unpack(arg))
            end
            return tmp
        end
    })
    klass.__index = function(table, key)
        local r = klass[key]
        if table ~= klass and type(r) == 'function' then
            return function(...) return r(table, unpack(arg)) end
        else
            return r
        end
    end
    return klass
end

function class_cache(super)
    -- create a new class description
    local klass = {}
    -- set the superclass (for object inheritance)
    setmetatable(klass, {
        __index = super,
        __call = function(self, ...)
            local tmp = {}
            setmetatable(tmp, klass)
            tmp.__method_cache__ = {}
            if self.init then
                self.init(tmp, unpack(arg))
            end
            return tmp
        end
    })
    klass.__index = function(table, key)
        local r = klass[key]
        if table ~= klass and type(r) == 'function' then
            local f = table.__method_cache__[r]
            if not f then
                f = function(...) return r(table, unpack(arg)) end
                table.__method_cache__[r] = f
            end
            return f
        else
            return r
        end
    end
    return klass
end

class = class_nocache

-- ######################
-- test the object system
-- ######################

object = class()
function object.method(self)
    return 1
end

o=object()
for i=1,100000 do
    o.method()
end