From: Leslie Viljoen <leslieviljoen@...>
Date: 2006-11-22T16:53:19+09:00
Subject: Re: [OT] Bug in ruby?

On 11/22/06, David Vallner <david@vallner.net> wrote:
> Leslie Viljoen wrote:
> > It's very annoying to try and guess which could be the offending
> > variable in a complex expression, and it wastes a lot of time. It
> > would surely be very easy for Ruby to say which variable was nil.
>
> Meet my good friends, local variable, and return value checking. You'll
> get along great once you get to know each other.
>
> Also, see previous post. At any given point in time, there's several
> variables that point to nil in the interpreter, and the culprit is also
> usually an expression. Finding the possible expressions that returned a
> nil would require tracing back to the literal in the stack frames, and
> even then the last one wouldn't have to be the cause of the problem. I
> stand by my point that this is not the job of a core language runtime,
> but of manual or automated code review.

It just seems like it would be easier than that, since Ruby is an
interpreter. Doesn't the last sub-expression get stored in a string
somewhere as the expression is parsed?

Anyway, I am just now noticing that 5+nil and nil+5 return different
error messages. As long as an operator is unique in an expression, it
should be easy to figure out which is nil.