From: Brian Candler <b.candler@...>
Date: 2009-08-04T21:59:21+09:00
Subject: Re: Inconsistency in Array#[]

Rob Biedenharn wrote:
> Just take a look at the definition of blank? (and present?) from the
> ActiveSupport gem
> 
> activesupport-2.3.2/lib/active_support/core_ext/blank.rb

I think that demonstrates a problem - there are different ideas of what 
"notempty?" means. In the case of ActiveSupport, a string which consists 
entirely of whitespace is "blank?", even though it is not "empty?"

> I typically add a NilClass#nonzero? just so nil plays nicely with
> Numeric#nonzero? myself.

I find it useful how Javascript treats 0 and "" as false (although 
strangely not an empty array). You can write things like

  emit(doc.foo || null);

to make things consistent - null and empty string both map to null.

Maybe there's a case for something that you can rely on being present at 
the Object level:

  class Object; def true?; true; end; end
  class NilClass; def true?; false; end; end
  class FalseClass; def true?; false; end; end
  class String; def true?; !empty?; end; end
  class Array; def true?; !empty?; end; end
  class Numeric; def true?; !zero?; end; end

Then 'true?' could be called automatically in boolean contexts, like 
'if' and 'and'. The latter would be a big language change though.

I think the problem with this idea is the same as above: people would 
disagree as to what's the natural definition of 'not empty', as it would 
vary from one application to another.
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