Re: Array.nitems replacement?

On Thursday 29 May 2008, Akinori MUSHA wrote:
> At Thu, 29 May 2008 03:03:01 +0900,
>
> David Flanagan wrote:
> > Am I missing something?  Is there a use-case for an Enumerator
> > returned by Enumerable#count?
>
> I think not.  Actually it is not official (I know it's not fair but I
> intentionally omitted it from rdoc and NEWS) that it returns an
> enumerator at the moment, and it would indeed be better if it returned
> something more useful and obvious from the name.
>
> My question is if counting the number of non-nil elements can be more
> useful and obvious than any other feature, such as:
>
> 1) counting the number of all elements (the same as size/length for Array)
> 2) counting the number of "true" elements (not nil nor false)
> 3) counting the number of unique elements ([1,2,3,4,2,2,1].count == 4)
>
> What do you think?

Well, from the name I would expect "count" to count elements and return the 
number of elements counted. Because otherwise it would be like "select", no ?

Maybe it would be nice to be able to tell it what to count for common 
use-cases:

array.count		# Like array.length
array.count :nonnil	# Return number of non-nil elements
array.count :true	# Return number of non-nil, non-false elements
array.count :unique	# Return number of unique elements
array.count {|x| x % 2 == 0 }	# Return "even" elements

Bye,
	Marc

-- 
Marc Haisenko

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