Re: [glob2-devel] scripting language

[Bo Lorentsen]

Stephane Magnenat wrote:

> Actually, glob2's scripts load/save are not handeled properly. Source code is 
> loaded, script is compiled, and then always run from beginning, even if a 
> saved game is reloaded.
>  
I understand why, as stopping in the middle of a script and then do a 
resuming a little later (and even persist in between) is not easy to do. 
The idea looks like some kind of cooperative multitasking project. This 
is possible but not pretty nor easy.

> SGSL does not have any variable except areas and flags, which are stored in 
> std::map and indexed by strings. Areas are square on map that can be used in 
> conditions. Flags are the normal glob2 flags. Both are global and shared by 
> threads. There is pointer to glob2's internal structure for flags, but as the 
> script is recompiled on each reload thatok,
>  
It sounds to me as a quite limited language, but it shows me something 
about the task a future script need to fulfill.

> Now we all agree that this is bad. So in the idea of a better script, we have 
> to fix those issues, but that also means that changing the script engine 
> doesn't break map format excepted that the old scripts will not compile. 
> There is no much old scripts :-) Only the tutorial, turretDefenseForTwo and 
> the campaign are using it.
>  
But if there was I guess making an SGSL -> TEA converter would not be 
that big of a task, as they would map 1:1 in functionality and framework.

> Just once requirement. A script for glob2 should have function overloading. It 
> is very usefull for things like show("blabla") and show ("blabla", fr). Do 
> you think it will be difficult to add to tea?
>  
I will give it a shot in my current revision, as I already have thrown 
myself into the task of making the executer a real VM (stack based) and 
not just a simple dump parser like structure. This a a somewhat large 
task, so why not include function overload too, so yes I think this 
would be possible, indeed.

> SGSL.h gives a quick overview. Story is a thread and Mapscript the script 
> interpreter. Mapscript::parseScript is the parser and token compiler. 
> Mapscript::syncStep does execute the threads by calling Story::syncStep.
>  
Ok, I will take a look at it tomorrow, and thanks for the hint.

/BL