From: bbiker <renard@...>
Date: 2007-12-30T08:10:05+09:00
Subject: Re: Add Array#first= and Array#last= to std lib

On Dec 28, 6:39 am, Robert Klemme <shortcut...@googlemail.com> wrote:
> 2007/12/28, Sebastian Hungerecker <sep...@googlemail.com>:
>
> > Robert Klemme wrote:
> > > I do not see why allowing last= would make lasts(n)= necessary.
>
> > For consistency. I believe that any method foo= should be equivalent to the
> > method foo except for the fact that it sets the value instead of getting it,
> > which in this case isn't possible (without changing the language). I mean,
> > that's not a major problem, but it'd feel a tad incosistent to me.
>
> You're right. Actually I was not aware that you could actually use an
> argument with last. Thanks for pointing that out!
>
> And I agree, that changes the situation a bit.  As a workaround you
> could implicitly use the number of elements when assigning an Array
> but I doubt it's a good idea.  What if you wanted the last element to
> be that array and not replace the last n elements?  That situation
> could not be distinguished. Hm...
>
> Re your other posting: yes, making last= behave like [-1]= is
> certainly a good idea.  So it's "throw an exception".
>
> irb(main):004:0> a=[]
> => []
> irb(main):005:0> a[-1]=123
> IndexError: index -1 out of array
>         from (irb):5:in `[]='
>         from (irb):5
>         from :0
>
> Also a tad inconsistent:
>
> irb(main):006:0> a[0]=123
> => 123
> irb(main):007:0> a
> => [123]
>
> So at least I now have an idea why last= is absent from the std lib.
> So the discussion was definitively worthwhile.
>
> Kind regards
>
> robert
>
> --
> use.inject do |as, often| as.you_can - without end

I mho, making #last= and #first=  adds nothing to ruby, the ability is
already available. So why bloat ruby unnecessarily?