Re: C with embedded Lua or Lua-only program?

[Philippe Lhoste <PhiLho@...>]

On 03/09/2010 03:55, Silas Silva wrote:
> 1. Is there any replacement for lex/flex&  yacc/bison for Lua?  How do
>     you design DSLs in Lua?  I thought about using Lex&  Yacc + C it is a
>     long standing wish of mine to learn parsers, BNF with Lex&  Yacc...

As said, Lpeg is well fit for the task. Not BNF, so it pushes you away 
from your wish, but still fun to use and powerful. Actually, it uses a 
kind of DSL itself to express the parser.

> 2. I was thinking that it would be interesting to make the DSL
>     Turing-complete, to make it easily programmable.  Use Lua itself as
>     the DSL would solve this problem, but what about if I need different
>     syntax not present in Lua, like in "button foo ..."?

You will be surprised to see the power and flexibility of Lua... People 
made surprising things with the Lua syntax pushed to surprising results, 
thanks to existing syntax sugar and metaprogramming.
Now, you need to have a good understanding of Lua to express what you 
want this way, and indeed you will need to express your DSL within the 
limitations of this syntax, ie. you won't be able to do anything you want.
On the other hand, you will get speed, some debug capability, etc. (IDE 
support if Lua was well supported...).

> 3. Is there any reason about why to develop it in C + Lua instead of Lua
>     only?

In some cases, speed (this have been discussed recently, the advantage 
is smaller with LuaJIT).
And obviously, to provide low level, system access (you won't display 
graphics with pure Lua!).
Traditional approach is to provide a core, small C application (too 
bootstrap), offering a number of services via libraries, and to write 
most of the logic in Lua. Going back to C if it is proved to be slow in 
some domains.

> 4. Am I reinventing the wheel?  If yes, could you point me to open
>     source solutions on this problem?

There are a number of GUI libraries for Lua, as mentioned, from wrappers 
to popular C GUI libraries to thin layers over the native components 
(IUP) or rewrite from scratch (drawing the components over a graphics 
frame) like tekUI.

I suggest to search the archives as most of them have been announced here.

Note: since they are open source, you can rewrite them (or add a layer) 
to use your own DSL for describing the GUI.

--
Philippe Lhoste
--  (near) Paris -- France
--  http://Phi.Lho.free.fr
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