Add array named setters

[lexmag]

For instance:

a = [*1..5]
a.third = 0  # Now `a` equal [1, 2, 0, 4, 5]

[steveklabnik]

You forgot forty_two=

[lexmag]

Done.

[rafaelfranca]

For me is ok to use named accessor, but setter seems very odd.

[lexmag]

Alright. Although Array#last= is useful.

[rafaelfranca]

Good point. I'll reopen to get more feedback.

[carlosantoniodasilva]

Except that it does not work for all cases: when the array is empty, last will throw you an error:

>> a = []
=> []
>> a[a.length - 1] = 'last!'
IndexError: index -1 too small for array; minimum: 0
...
>> a[-1] = 'last!'
IndexError: index -1 too small for array; minimum: 0

I personally disagree with the idea of adding similar helpers to Active Support, since these helpers are probably not going to be used internally by the framework (and possibly by most users). It looks like a method I'd have to look at the implementation to see what's going on. Anyway, thanks for the contribution @lexmag :)

[vijaydev]

-1. What @carlosantoniodasilva said.

[lexmag]

@carlosantoniodasilva, thanks for the feedback. I could fix last method and replace [1/2/3] = internally by these helpers, but you are right - "if it ain't broke, don't fix it".