-- LUA Stack L
function foo( str1 )
print( "My String was " .. str1)
end
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call a lua function from c
Author
Hi,
for some time I'm trying to find out if it is possible to execute a function at the lua stack from C++?
For example:
You may be able to use lua_load for this; just pass in the Lua code that you want to execute (eg. "foo(test)"). I think you then have to call another function to execute the top of the stack.
If you use LuaLoad and load your file with the lua_functions, then you can use something like this, which I use in all of my lua/C/C++ interfaces:
I think I have the defines going all of the way up to 16 arguments or something like that. To use the defines, do something like this:
If you would rather do it by hand and create a wrapper function which takes variable # of arguments along with some info about the calling function like it's name, the number of arguments it takes, and if there is a return value (lua is OK with multi returning values, but C isn't so you dont have to worry about it)
Hopefully those examples made some sence and clearified how C can interface to the lua functions provided in lualib.
Hope I've helped!
Dwiel
EDIT: Make sure you put the backslashes in for the defines if you use my #defines, they messed up the formatting so I removed them
#define luafunc0(_NAME, R) R lua##_NAME(){ R ret; lua_getglobal(L, #_NAME); lua_call(L, 0, 1); ret = (R)lua_tonumber(L, -1); lua_pop(L, 1); return ret;}#define luafunc1(_NAME, R, T1) R lua##_NAME(T1 a1){ R ret; lua_getglobal(L, #_NAME); lua_pushnumber(L, a1); lua_call(L, 1, 1); ret = (R)lua_tonumber(L, -1); lua_pop(L, 1); return ret;}#define luafunc2(_NAME, R, T1, T2) R lua##_NAME(T1 a1, T2 a2){ R ret; lua_getglobal(L, #_NAME); lua_pushnumber(L, a1); lua_pushnumber(L, a2); lua_call(L, 2, 1); ret = (R)lua_tonumber(L, -1); lua_pop(L, 1); return ret;}...#define luafunc0v(_NAME) void lua##_NAME(){ lua_getglobal(L, #_NAME); lua_call(L, 0, 0); return;}#define luafunc1v(_NAME, T1) void lua##_NAME(T1 a1){ lua_getglobal(L, #_NAME); lua_pushnumber(L, a1); lua_call(L, 1, 0); return;}#define luafunc2v(_NAME, T1, T2) void lua##_NAME(T1 a1, T2 a2){ lua_getglobal(L, #_NAME); lua_pushnumber(L, a1); lua_pushnumber(L, a2); lua_call(L, 2, 1); return;}...I think I have the defines going all of the way up to 16 arguments or something like that. To use the defines, do something like this:
-- lua codefunction add ( x, y ) return x + yendfunction fn ( ) print( "Inside fn()" )end// C/C++ Codeluafunc2(add, int, int, int)luafunc0v(fn)cout << "2 + 3 = " << luaadd(2, 3) << endl;luafn();If you would rather do it by hand and create a wrapper function which takes variable # of arguments along with some info about the calling function like it's name, the number of arguments it takes, and if there is a return value (lua is OK with multi returning values, but C isn't so you dont have to worry about it)
Hopefully those examples made some sence and clearified how C can interface to the lua functions provided in lualib.
Hope I've helped!
Dwiel
EDIT: Make sure you put the backslashes in for the defines if you use my #defines, they messed up the formatting so I removed them
lua_dostring does just that.
Do lua_dostring( L, "foo( 'test' )" );
Requires to have the lua instance L to parse the function before (duh!).
You can also do it via the stack, but i don't know the sequence how to put the params on the stack off my head. lua_pushstring the params, then lua_pushstring the function name and then call lua_call (spelling?). I might have messed up this second possibility, i usually use the first one.
Do lua_dostring( L, "foo( 'test' )" );
Requires to have the lua instance L to parse the function before (duh!).
You can also do it via the stack, but i don't know the sequence how to put the params on the stack off my head. lua_pushstring the params, then lua_pushstring the function name and then call lua_call (spelling?). I might have messed up this second possibility, i usually use the first one.
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