Re: Say No to global-by-default (summary of the discussion)

[Luiz Henrique de Figueiredo <lhf@...>]

If you really want to play with this idea, here is a patch for Lua 5.3.5:

diff llex.c noglobal/llex.c
547a548
> #include "proxy.c"

diff lparser.c noglobal/lparser.c
284c284,286
<         if (var->k == VVOID)  /* not found? */
---
>         if (var->k == VVOID)  /* not found? */ {
>           luaX_syntaxerror(fs->ls,
>               luaO_pushfstring(fs->ls->L,"undeclared global " LUA_QL("%s"),getstr(n)));
285a288
>       }

% cat test.lua
\a=3
\print(\a)
\print(a)

% cat proxy.c
/*
* proxy.c
* lexer proxy for Lua parser -- implements '\' -> '_ENV.'
* Luiz Henrique de Figueiredo <lhf@tecgraf.puc-rio.br>
* This code is hereby placed in the public domain.
* Add <<#include "proxy.c">> just before the definition of luaX_next in llex.c
*/

static int nexttoken(LexState *ls, SemInfo *seminfo)
{
        static int state=0;
        int t;
        if (state==0) {
                t=llex(ls,seminfo);
                if (t=='\\') {
                        state=1;
                        seminfo->ts=ls->envn;
                        t=TK_NAME;
                }
                return t;
        } else {
                state=0;
                return '.';
        }
        return t;
}

#define llex nexttoken