Re: Problems with bubbling up tracebacks in Lua (& proposed solution)

[petah <lua@...>]

On Sun, 22 Sep 2013 10:54:28 -0300
Luiz Henrique de Figueiredo <lhf@tecgraf.puc-rio.br> wrote:

> > By the time you intercept a native Lua error it's already converted to a string by the Lua VM, so you don't need to handle another data type...
> 
> The Lua VM does not convert error values to string.

Is this true beyond the 7 high-level LUA_xxx integer error identifiers? AFAIK, VM errors are flattened to a string via luaL_error/luaG_runerror before reaching a user-overridable error callback.

If this string conversion were deferred, say by encapsulating the error arguments (currently passed to lua_pushvfstring/luaO_pushvfstring) inside an error object, it'd give a user-installed error callback "raw" data to base logic on. Adding a __tostring metamethod to this error object (table) would seem to preserve the current behavior.

A unique error identifier would be great but could also be inferred from the vararg's fmt.

my 2 cents.

-- p