From: "Guy N. Hurst" <gnhurst@...>
Date: 2001-06-16T18:04:03+09:00
Subject: [ruby-talk:16533] Re: why only nil and false are regardedas false?


Steven Haryanto wrote:
> ...
> >Do you have some examples where you'd like other values to be false?
> 
> So far my mind has been fitted with these idioms:
> 
>   # if string s is empty
>   if (not s) ...
> 

if s.empty?  then .... end  # assumes you know s is a string

>   # if number is zero
>   if (not n) ...
>

if n.zero?  then .... end  # assumes you know n is a number
 
>   # if there are no elements in array a
>   if (not a) ...
>

if a.empty?  then .... end # assumes you know a is an array
 
> I believe this idiom goes as far back as C and perhaps even further.
> However, in Ruby they will all be wrong. What are the preferred way
> to do this?
> 

As above.  Note that Ruby variables refer to objects of a specific
class, and you must pass methods that you know the referenced object
can handle - or you'll get an error. There are ways to deal with this, though.


Guy N. Hurst


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