Re: [Enigma-devel] Re: network 2-player game

[Tacvek]

----- Original Message ----- 
From: "Ronald Lamprecht" <address@hidden>
To: "Tacvek" <address@hidden>
Cc: "enigma-devel" <address@hidden>
Sent: Friday, March 17, 2006 1:56 PM
Subject: Re: [Enigma-devel] Re: network 2-player game


> But how far do the changes in the error system affect existing levels
> and Enigma itself? Please provide us all information you have.

My previous message answeing this question was somewhat unclear.
I'm not sure what effect the error change would have on the levels. If any 
level attempts
to check to errors using "call" then then they sould upgrade to "pcall". 
_LASTERROR will no longer
be available.

It does require some changes to the main enigma code.

Lua 4.0 used to call _ERRORMESSAGE, which by default was _ALERT, whenever 
there was an error.
The error would propagate upward, except in cetain circumstances. One such 
circumstance was calling Lua code from C.
The error would not progagate beyond C unless explicity told to.

In Lua 5 this is different. Errors normally propagate upwards. The only real 
way to deal with errors in lua code is to use pcall, rather than call.
pcall works pretty much the same, except in the case of error. If there is 
no error pcall returns true. If there is an error, pcall returns 2 values: 
"false", and the error string.

A similar system is used with c code. I'm currently tring to upgrade Enigma 
to Lua 5.1.
Lua 5.1 contains some is mostly the same as 5.0 but happens to contain a few 
additional compatability macros that would help.

If I am successfull I will send a patch. I will not be updating the lua 
scripts, but I belive that
all the nessisary information can be found at:
http://www.lua.org/manual/5.0/manual.html#BNF (scroll up a bit)
and
http://www.lua.org/manual/5.1/manual.html#incompat

(Note my patch would neglect things like the changelog entries but compaired 
to the relative difficulty of changing the c code, that would be easy for 
somebody else to supply on my behalf. I will also likely need to switch to 
tolua++ to be able to support Lua 5.1).