Re: Stack traces with tail calls: disabling tail recursion?

[Philipp Janda <siffiejoe@...>]

Am 25.02.2014 11:14 schröbte Dirk Laurie:
> 2014-02-25 11:51 GMT+02:00 Ico <lua@zevv.nl>:
>
> > Are there other people out there who are having issues with tail call stack
> > traces, and if so, how dow you handle this in real life debugging?
>
> You could avoid tail calls until the program is debugged.
>
> A tail call arises in this situation:
>
>     return func(x,y,z)
>     end
>
> If you don't know how many values func will return, you're stuck with
> the tail call.
>
> Otherwise you can do:
>
>     local a,b,c = func(x,y,z)
>     return a,b,c
>     end

Well, you could do something like this:

    return notail( func( x, y, z ) )

where `notail` is

    function notail( ... )
      return ...
    end

to avoid the original tail call, but this also requires an application 
restart. It could still be useful if you only want to disable a single 
tail call site. There is a Lua 5.2 parser in the rocks repository, so 
maybe one could write a script that adds/removes the `notail` 
instrumentation automatically ...

Personally, I haven't had the problem yet. I usually don't have multiple 
different tail calls per function, so the stack traces are still 
non-ambiguous.

Philipp