Re: report on the Lua in the Gaming Industry Roundtable at GDC 2004

[Dario Accornero <adario@...>]

On 16 Apr 2004, at 1:12, Ashwin Hirschi wrote:

> I think another reason might be that a Lua-C/C++-Lua transition is 
> relatively expensive. So reducing the number of Lua calls to a C++/C 
> engine, like your calling everything in one go approach, will be 
> cheaper. Though I'm not sure exactly how big the savings are in 
> real-world examples...

I have a gdb window open right now, and here's what I see:

0. my C++ code				[breakpoint here]
1. Lunar<myclass>::thunk
2. luaD_precall
3. luaV_execute
4. luaD_call
5. f_call
6. luaD_rawrunprotected
7. luaD_pcall
8. lua_pcall
9. Lunar<myclass>::call

The Lunar calls represent the price I pay for using this particular 
interface, and I'm fine with that.  On the other hand, the seven stack 
frames required in any case to reach my own code look quite expensive 
indeed.  Obviously I'm not claiming that I could make it in any way 
faster -- I'm just saying that I completely understand the need for 
grouping multiple Lua invocations in a single one, and I'll try to 
implement said mechanism.

Dario