From: Robert Klemme <bob.news@...>
Date: 2003-09-11T16:31:46+09:00
Subject: Re: What *are* variables? Which are nil now?


"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
>
> class Nil
>    def to_a
>       raise "nil.to_a() called"
>    end
> end
>
> 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

Cheers

    robert