Re: Arguments for a module loader

[Matthias Kluwe <mkluwe@...>]

Hi!

2012/8/7 Sean Conner <sean@conman.org>:
> It was thus said that the Great Matthias Kluwe once stated:
>> [...]

>   The major issue with your code is the use of lua_typename()---it doesn't
> do what you think it does.  lua_typename() returns the name of the given
> type, such that 1 is LUA_TBOOLEAN, 2 is LUA_TUSERDATA.  To get the type at
> the given stack index, use luaL_typename().  If you try this:

Oh, I really laughed loud realising I managed to invent a misuse which
mimicked that it almost worked. Nice.

> #include <stdio.h>
> #include <lua5.2/lua.h>
> #include <lua5.2/lauxlib.h>
>
> int luaopen_mod( lua_State *L ) {
>    printf( "stack size  : %d\n", lua_gettop( L ) );
>    printf( "typename   1: %s\n", luaL_typename( L, 1 ) );
>    printf( "typename   2: %s\n", luaL_typename( L, 2 ) );
>    printf( "value      1: %s\n", lua_tostring( L, 1 ) );
>    printf( "isuserdata 2: %d\n", lua_isuserdata( L, 2 ) );
>    printf( "isstring   2: %d\n", lua_isstring( L, 2 ) );
>    printf( "value      2: %s\n", lua_tolstring( L, 2, NULL ) ); /* [1] */
>
>    /*-----------------------------------------------------------------------
>    ; [1] - please, please, please, ifyou are writing in C, use NULL instead
>    ;       of a 0.  Even though NULL is 0, using NULL portrays the intent
>    ;       better than a 0.  It also stands out more.
>    ;
>    ;       If you are writing in C++, you have my condolences. [2]

Yes, thank you.

>    ;
>    ; [2] - Okay, my bias is showing through.  Sorry.
>    ;----------------------------------------------------------------------*/
>
>    lua_newtable( L );
>    return 1;
> }
>
> You should see:
>
> stack size  : 2
> typename   1: string
> typename   2: string
> value      1: mod
> isuserdata 2: 0
> isstring   2: 1
> value      2: ./mod.so
>
>   The first parameter is the string given to require() (compatible with Lua
> 5.1) while the second paramter is the filename that contains the module (new
> for Lua 5.2).

It does here as well. Thank you for your answer.

So I guess this is what the sentence "Once a loader is found, require
calls the loader with two arguments: modname and an extra value
dependent on how it got the loader. (If the loader came from a file,
this extra value is the file name.)" means for a standard C (in my
daily work: C++) module: the module name and the module filename.

Regards,
Matthias