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

[Philipp Janda <siffiejoe@...>]

Am 25.09.2013 15:38 schröbte Enrique Garcia Cota:
> Hello Philip,

Hi!

> Thanks for answering. I am afraid your example assumes I have control over
> the how the errors are thrown in the first place - that is not the case.

Ah, I assumed, because you proposed an extra argument to `error`. Do you 
have control over how the errors are caught? If so, maybe you can use 
the modifications below ...

> [...]
>
> Regards,
>
> Enrique

Philipp


> On Wed, Sep 25, 2013 at 12:26 PM, Philipp Janda <siffiejoe@gmx.net> wrote:
> >      local err_meta = {
          __tostring = function( e )
            e[ 1 ] = tostring( e[ 1 ] )
            return table.concat( e, "\n" )
          end,
> >      }
> >      local function make_error( s )
> >        return setmetatable( { s }, err_meta )
> >      end
> >      local function err_traceback( e )
          if type( e ) ~= "table" then
            e = make_error( e )
          end
> >        e[ 2 ] = e[ 2 ] or debug.traceback( nil, 3 )
> >        return e
> >      end
> >
> >      local function a()
          error( "argh" )
> >      end
> >
> >      local function b()
> >        local ok, err = xpcall( a, err_traceback )
> >        err[ 1 ] = string.upper( err[ 1 ] ) .. "!!!!"
          err[ 3 ] = debug.traceback( nil, 1 )
> >        error( err )
> >      end
> >
> >      b()
> >
> >
> > Output is (using the Lua 5.2 default interpreter):
    lua: ERR.LUA:20: ARGH!!!!
    stack traceback:
    	err.lua:20: in function <err.lua:19>
    	[C]: in function 'xpcall'
    	err.lua:24: in function 'b'
    	err.lua:30: in main chunk
    	[C]: in ?
    stack traceback:
    	err.lua:26: in function 'b'
    	err.lua:30: in main chunk
    	[C]: in ?