From: "ara.t.howard" <ara.t.howard@...>
Date: 2007-10-13T11:42:58+09:00
Subject: Re: range max


On Oct 12, 2007, at 8:05 PM, Brian Adkins wrote:

>>
>> 0 ... 1
>>
>> we know that max != 0, so
>
> Wrong. (0...1).max_int -> 0 (see code in other post)

you code does not return the max, it returns the 'end', and  
incorrectly in some cases.

any range/interval whose end > start *must* have size > 0.  therefore  
the max cannot == start.  i think you are confusing the concept of  
sequence with that of a range

   http://en.wikipedia.org/wiki/Sequence                    # sequence
   http://en.wikipedia.org/wiki/Interval_%28mathematics%29  # range

there is *no* constraint on ruby ranges to be either - one may use  
the range to represent either.  if one uses it to represent an  
interval the, with an open ended (... vs ..) range there is no way to  
compute the max.  this is a very useful property because you can use  
it to do things like

  f = 0.42

  r = 0 ... 1

  if f > r.start and f < r.end

    ...

so, if we are talking general purpose methods, which the OP was,  
Range#max cannot be written to be general purpose, even for integer  
'ranges'

>
>> max = 0.9?
>> max = 0.99?
>> max = 0.999?
>> max = 0.9999?
>
> What the heck are you talking about? Do you really think that 0.9 or
> 0.99 is in the range (0...1) ?

yes.  but it is not in the integer sequence.

regards.

a @ http://codeforpeople.com/
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