From: progcat@...
Date: 2007-04-18T12:10:10+09:00
Subject: Re: nil in evaluations

Close but not really what I was looking for.

example:
   if g(x) > f(x)
   then
       put "rejoice because f(x) is greater than f(x)"
   else
       put "g(x) <= f(x) OR g(x) and/or f(x) returned a nil so I
wanted to execute this"
   end.

In other words I want the function to work as it normally would for
valid values, and if one or both are nil I want to make the test
evaluate to false.

Sorry I was not clear.

Thanks,
Tom

On Apr 17, 9:42 pm, Prime wrote:
> I am not sure this is what you wanted but,
>
> if g(x).nil? || f(x).nil?
>         p "nil found"
> else
>         p "no nil"
> end
>
> can be used to evaluate if the function equals nil
>
> On 2007-04-17 19:08:05 -0700, prog...@comcast.net said:
>
>
>
> > Problem:  I have functions that sometimes evaluate to nil and cause my
> > program to crash in comparisons, etc.
>
> > For example g(x) and f(x) either could be nill in the following:
> > if g(x) > f(x)
> >      p "not reached"
> > else
> >      p "also not reached but I want it to reach here if either fuction
> > returns nil"
> > end
>
> > What can I do to make any comparison that has nil in it to evaluate to
> > false?  I have seen operator overloading and class definitions in
> > ruby, so I imagine this would be quite simple.
>
> > (I know I can set g(x) and f(x) to variables before the if statement,
> > but I really want to avoid that)
>
> > Thanks in advance,
> > Tom