Re: Attn : Ron Bessems and other Delphi users

[Romulo Bahiense <romulo@...>]

> Hello,

	Hi.

> There seem to be many pascal scripting
> components in delphi, but if possible I would like to use something I
> can also use stand-alone (for those occasions where a full-fledged
> delphi app would be over-kill).

	Yes, there are lots of them. But in the end, they are all the same thing.

> However, I am not a C programmer and I find it hard to get a feel for
> what is possible when it comes to linking lua to other languages than
> C.

	You are not alone. The biggest problem about Lua [community] is that 
everybody thinks you have a C compiler and also have knowledge on how to 
use it wisely. No binaries for us (and no donnuts for Orkut's server) :(

[Please, no comments about how I'm stupid or lazy, ok? ;)]

> I would be very interested in any information you have on integrating
> lua with Delphi. 

	It's very simple. Look at LuaForge.net and you will find an up-to-date 
binary with header [Lua 5.0.2] translated to Pascal ready to use. If I 
recall right, the name is LuaPas.

> How do the lua environment and the delphi environment
> integrate? What are the limitations? Is a two-way binding doable /
> elegant / stable / hackish ?

	Good question. The main difference is that all Lua's external functions 
are cdecl'ed. That just mean that you will have to get used to write 
'cdecl;' after many functions :).	I myself don't see any other 
limitation (except 'that' quoted above).

	About the two-way binding, it is possible [partially at least] but can 
be a little tricky in the beggining (what isn't?). I haven't seen any 
project to automate the proccess of binding between Lua and Delphi, so I 
made one myself (there were a discussion some months ago about a 
possible 'topascal', but ended up with nothing). It's not pretty nor 
full optimized, but works.

	I was about to send some details about my solution, but the message was 
getting very big (just like Delphi executables - you start with 
something small and then when you see, it became a 6MB snowball).

	In short, what I would say is that everything is doable in an elegant 
way, except events. Basically the main problem is that the pascal 
calling convention is far different from the cdecl calling convention. 
It is possible, but I don't know if the costs are worthy it.


> In short, I would very much like to hear whatever information, war
> stories, source examples you want to share, urls to other information
> that helped you out with the problems you had implementing, the lot.

	Well, I can send you what I have, but you will probably throw it in the 
trash, because it's still a little messy -- except for the TLuaObject 
object (not class). It does nothing except cutting the

" lua_<something>(L,...) "

to

" Lua.Something(...) "

Very efficient to use. With just a typecast, you have:

with TLuaObject(L) do
begin
	PushString('Me');
	PushString('Too');
	RawSet(LUA_GLOBALSINDEX);

	// Or...
	SetNamedString('Me', 'MeToo', LUA_GLOBALSINDEX);
end;



--rb