Re: accessing local functions fom c.

[Peng Zhicheng <pengzhicheng1986@...>]

于 2012-4-13 23:47, dderny 写道:

In a program I have :

 

 

function x()

 print(“global x”)

end

 

 

function y()

                local function x()

                      print(“local x”)

             end

           call_to_c_function()

end

 

y()

 

from the c function I would like to call

1/ the local x function in y (if available)

2/ the global x func if available.

 

I have no problem to call the global x function

But no idea on how I could call the localone

 

Any idea ?

 

 

Thanks

 

 

 

 

 

 

No, you can't access that local function x since its scope is only within function y itself, but not the function called by y.
this is the so called `lexical scoped language'

you may pass a closure of the inner local function x as a parameter to the C function. like this:

  function y ()
      local function x ()
        ...
      end
      SOME_C_FUNCTION(x)
  end

  int SOME_C_FUNCTION (lua_State *L) {
    ...
    lua_pushvalue(L, 1);
    /* push the parameters */
    lua_call(L, ...)
    ...
  }


---------------------------------------------------------

HACK:
btw, you may use the following hack if you are familiar with the implementation of Lua.
this would require accessing inernal data structures of lua, and your C code must be compiled as part of lua and be static linked.
note that use lua's internal implementation detail is NOT recommended. it is totally hack.
but in case you are curious, here is the method:

   from your C function, get a pointer to the closure y which calls the C function. then you can get the Proto of function y,
   and then the Proto of the inner function x. then create a closure for the Proto and call it.