Question

I have a strange behaviour with the hook mechanism which i don’t understand and id love some help.

It’s quite a simple example as i am studying the language :

foo function :

 function foo () print ("i'm in foo") end

some data function :

 function data () print ("This is the data : ") end

Then i do the hook set up :

debug.sethook(data , "c")

And the wired thing is when i call foo this is the output i get :

This is the data : 
This is the data : 
This is the data : 
This is the data : 
i'm in foo

This is the entire program, so no hidden stuff that could cause it.

I was wondering why is the hook being called 4 times and not just once?

Answer 1

In the program below, I see only 3 messages, not 4. The explanation is that the call hook is called for each call after it is set: foo, print, tostring, which is called by print.

function foo () print ("i'm in foo") end
function data () print ("This is the data : ",debug.traceback()) end
debug.sethook(data , "c")
foo()