Re: state of the Lua nation on resource cleanup
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- Subject: Re: state of the Lua nation on resource cleanup
- From: Renato Maia <maia@...>
- Date: 2009年1月20日 23:24:34 -0200
On 20 Jan 2009, at 22:07, Sam Roberts wrote:
One can pass anything to error, no?
No.
% lua
Lua 5.1.2 Copyright (C) 1994-2007 Lua.org, PUC-Rio
error({type="This"})
(error object is not a string)
My guess is this will probably change in Lua 5.2 with the new
'luaL_tolstring' (see http://lua-users.org/lists/lua-l/2008-02/msg00720.html)
. Anyway, it can be easily "fixed" in the 'lua.c' with something like:
--- src/lua.original 2007年12月28日 13:32:23.000000000 -0200
+++ src/lua.c 2009年01月20日 22:41:45.000000000 -0200
@@ -74,8 +74,17 @@
static int traceback (lua_State *L) {
- if (!lua_isstring(L, 1)) /* 'message' not a string? */
- return 1; /* keep it intact */
+ if (!lua_isstring(L, 1)) { /* 'message' not a string? */
+ lua_getfield(L, LUA_GLOBALSINDEX, "tostring");
+ if (lua_isfunction(L, -1)) {
+ lua_insert(L, -2);
+ lua_call(L, 1, 1);
+ }
+ else lua_pop(L, 1); /* pop 'tostring' */
+ if (!lua_isstring(L, 1)) { /* 'message' is still not a string? */
+ return 1; /* keep it intact */
+ }
+ }
lua_getfield(L, LUA_GLOBALSINDEX, "debug");
if (!lua_istable(L, -1)) {
lua_pop(L, 1);
With such change you could do:
Lua 5.1.3 Copyright (C) 1994-2008 Lua.org, PUC-Rio
> Exception = setmetatable({
>> __tostring = function(self) return "Exception raised:
"..self.message end
>> }, {
>> __call = function(cls, obj) return setmetatable(obj, cls) end
>> })
>
> error(Exception{
>> message = "some fancy error message",
>> errorcode = 1234,
>> stack = debug.traceback(),
>> })
Exception raised: some fancy error message
stack traceback:
[C]: in function 'error'
stdin:1: in main chunk
[C]: ?
We use a similar approach in OiL to map CORBA exceptions. But users do
have a lot of trouble when using it in the standard Lua console. For
more info see:
http://oil.luaforge.net/manual/corba/mapping.html#exception
--
Renato Maia
PhD student at PUC-Rio
__________________________
http://www.inf.puc-rio.br/~maia/