Re: How does one find a loop in a gettable chain?
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- Subject: Re: How does one find a loop in a gettable chain?
- From: Sean Conner <sean@...>
- Date: 2016年2月18日 16:28:32 -0500
It was thus said that the Great Dirk Laurie once stated:
> I'm getting the following error:
>
> gettable chain too long; possible loop
>
> It's difficult to locate the error by my usual technique
> of sprinkling print statements around. This may be
> a case where the debug library is needed.
>
> The traceback is of little use. It contains only the
> outermost call, which is almost the only statement
> in the main chunk.
You could trying wrapping the topmost call with xpcall(). I do that at
work and use the following message handler:
function stackdump(...)
local max = select('#',...)
for i = 1 , max do
syslog('debug',"Stack: %d %d %s",i,i-max-1,tostring(select(i,...)))
end
local stack = {}
for i = 1 , 10 do
local info = debug.getinfo(i,"Sl")
if not info then break end
table.insert(stack,string.format(" [%s(%d)]",info.source,info.currentline))
end
syslog('debug',"stack=%s",table.concat(stack))
return ...
end
I use syslog() because I might not *have* a terminal, but it should be easy
enough to replace syslog() with print().
-spc (I tend to log to syslog() as I have a real time view of it [1][2])
[1] https://github.com/spc476/syslogintr
It's a syslog daemon written in C and Lua.
[2] I have syslogintr configured to forward logs to a multicast
address. I can then run other instances of syslogintr to listen on
this address and the most common use I use of this is to view the
logs in realtime (and color coded: https://github.com/spc476/syslogintr/blob/master/realtime.lua)