Re: game developers?

[David Jeske <jeske@...>]

On Fri, Jul 28, 2000 at 02:47:40PM -0300, Luiz Henrique de Figueiredo wrote:
> >>From lua-l@tecgraf.puc-rio.br  Wed Jul 19 00:06:22 2000
> >From: David Jeske <jeske@chat.net>
> >
> >In closing, most of my Lua-wish-list features are pulled right out of
> >Python:
> > - simultaneous support for integer and floating point types
> 
> Sometimes I think about this too, but in the end it always seems to complicated
> to be worth it, plus it would probably bring a performance hit.
> If you really need integers, then you probably do not need floating point...

Actually, my bigggest unsolved problem in this area is that I want to
be able to use 32-bit floating point AND be able to represent a
time_t. I end up using doubles just so I can handle units of time
reliably, which is somewhat of a waste. 

> > - linked-list datatype 
> 
> Why do you need that?
> Tables in Lua are *the* data structure and everything else can be implemented
> with tables quite efficiently. What is wrong with a.next and a.prev?

1) a.next and a.prev is relatively slow (it's about 1/2 the speed of
   Python lists, see comparison below)

2) a.next and a.prev can't handle very large lists.  I originally
   wanted to do 500000 iterations of the list_append_test, but 
   Lua3.2 and Lua4.0a both segfault when I try that many iterations.
   (Do you have any idea why?)

Here is a comparison of Python and Lua40a with the Lua list containing
{ count, head, tail } and the elements containing {next, prev, item}.

Python:
  list_append_test        50000   elapsed:        1.04663002491 seconds
  list_traverse_test      500000  elapsed:        13.8836849928 seconds

  http://www.chat.net/~jeske/Projects/ScriptPerf/download/all_test.py
 
Lua4.0a:
  list_append_test        50000   elapsed:        1.814723
  list_traverse_test      500000  elapsed:        23.28007

  http://www.chat.net/~jeske/Projects/ScriptPerf/download/all_test.lua

> > - next tag-method (so you could truly implement a new type of table
> >     or list datastructure. Although I assume Lua does not
> >     have it because it's more complicated than it seems.)
> 
> Yes, the semantics of a "next" tag method seems too complicated.

I worked on a solution to this for a while, and was mostly left
frustrated. Perhaps someday my mind will grab hold of an elegant
solution.

> > - Python style "for x in [a, b, c]" loop
> 
> Lua 4.0 wil have this in the form
> 	for i,v in {a,b,c} do ... end
>
> Of course, any expression can appear in the place of {a,b,c}.

Is it using next() order or numeric order?

-- 
David Jeske (N9LCA) + http://www.chat.net/~jeske/ + jeske@chat.net