From: Hugh Sasse Staff Elec Eng <hgs@...>
Date: 2003-09-11T19:02:21+09:00
Subject: Re: What *are* variables? Which are nil now?

On Thu, 11 Sep 2003, Robert Klemme wrote:

>
> "Hugh Sasse Staff Elec Eng" <hgs@dmu.ac.uk> schrieb im Newsbeitrag
> news:Pine.GSO.4.53.0309110023200.26201@neelix...
> > I found out what caused it:
> >    @dirs += entries.collect{|f| stuff_here(f)}.compact!
> >
> > The bang method caused the blow up, but even defining
> >
        [Nil#to_a]
> >
> > did not trap it.
> > Where does the "#<"..."failed to convert nil to Array"...>
> > message come from? Somewhere untrappable?
>
> Since
>
> @dirs += entries.collect{|f| stuff_here(f)}.compact!
>
> <=>
>
> @dirs = ( @dirs + entries.collect{|f| stuff_here(f)}.compact! )
>
> Assuming that @dirs is an Array, Array.+ tries to convert the argument
> (which is the result of the expr right to the "+") to an Array and throws
> the exception

Agreed, but is the point where the message is generated accessible,
such that I can interpose something?  This Array#+ isn't calling
arg.to_a as far as the above shows...
>
> Cheers
>
>     robert

        Hugh