Re: The first Lua library

[luciano de souza <luchyanus@...>]

Romulo, I think I am closer, but the error persists. I do two
modifications. I fixed the syntax of lua_tonumber and I declared x and
y as lua_number and not integer. The code compiles, but it crashhes.
Thijs, I corrected the indexes. The "2" was lacking!

library opr;
{$calling cdecl}
{$mode objfpc}{$H+}

uses
lua;

function sum(l: plua_state):integer;
var
x, y: lua_number;
begin
x := lua_tonumber(l, 1);
y := lua_tonumber(l, 1);
lua_pushnumber(l, x+y);
result := 1;
end;

function luaopen_opr(l: plua_state):integer;
var
r: array[0..1] of luaL_reg;
begin
l := lua_open;
luaL_OpenLibs(l);
r[0].name := 'sum';
r[0].func := @sum;
luaL_openlib(l, 'opr', @r, 0);
lua_close(l);
result := 1;
end;

exports
luaopen_opr;
END.



2012/11/6, Thijs Schreijer <thijs@thijsschreijer.nl>:
> Try this;
>
> function sum(l: plua_state):integer;
> var
> x, y: integer;
> begin
> x:= lua_tonumber(l, 1);
> y:= lua_tonumber(l, 2);
> lua_pushnumber(l, x+y);
> result := 1;
> end;
>
> Might not be completely correct, bit rusty on my Pascal after two decades.
> :)
>
> Thijs
>
> Sent from my espressomachine
>
> luciano de souza <luchyanus@gmail.com> wrote:
>
>>Hello listers,
>>I am trying to understand the basic mechanism of Lua stack
>>registrations. This Pascal code compiled, but I have a run-time error.
>>As it's an generic error, I could not identify what's wrong.
>>
>>library opr;
>>{$calling cdecl}
>>{$mode objfpc}{$H+}
>>
>>uses
>>lua;
>>
>>function sum(l: plua_state):integer;
>>var
>>x, y: integer;
>>begin
>>lua_tonumber(l, x);
>>lua_tonumber(l, y);
>>lua_pushnumber(l, x+y);
>>result := 1;
>>end;
>>
>>function luaopen_opr(l: plua_state):integer;
>>var
>>r: array[0..1] of luaL_reg;
>>begin
>>l := lua_open;
>>luaL_OpenLibs(l);
>>r[0].name := 'sum';
>>r[0].func := @sum;
>>luaL_openlib(l, 'opr', @r, 0);
>>lua_close(l);
>>result := 1;
>>end;
>>
>>exports
>>luaopen_opr;
>>end.
>>
>>In the Lua code, I would like to do it:
>>
>>require('opr')
>>
>>print(opr.sum(3, 5))
>>
>>I follow C API and I believe the fact it was writen in Pascal won't
>>create difficulties for the discutions.
>>These are my first steps in C API. Do they seem to be wrong? Does
>>someone have any tip for me?
>>Regards,
>>Luciano
>>
>


-- 
Luciano de Souza