From: Sam Roberts <sroberts@...>
Date: 2006-10-21T02:33:24+09:00
Subject: Re: String not enumerable, what about IO?

On Fri, Oct 20, 2006 at 01:24:29PM +0900, Michael Selig wrote:
> 1) There are several methods in Array which I think could (should?) also be
> in Enumerable (eg: uniq, +, | etc).
> 
> 2) Presumably, as an alternative to most of the Enumerable methods, you
> could use "to_a", and then use Array methods. I guess the Enumerable methods
> would be more efficient than doing this, so is that the reason for using
> them, or is it brevity or something else?

Probably not more efficient, you have to build an Array internally to
sort, for example.

> 3) It has been mentioned before that Enumerable is a collection, which is
> unordered (ie: you can't index them). However characters or lines in a
> string or file *are* ordered. When you iterate over them you expect them to
> come back in order.

I think 

  a[2] == a[2]

should always be true, but there are things that are Enumerable that
truly are unordered, and if Enumerable just did an #each_with_index
pulled out the matching index, the above wouldn't be true.

> 4) Other posts proposed having String#lines & String#bytes return an Array,
> so the same efficiency comment as (2) applies. They could also return an
> Enumerable object, which maybe more efficient but this relies on "each"
> returning them in order (which it probably would!).

Probably for Array, String, and IO, but Enumerable is used more than
that.

> Array methods available (delete, insert etc). May be a new module, rather
> than polluting Enumerable?

Maybe Arrayable?

But remember that every method in Enumerable is implemented in terms of
the underlying #each.

How would you define a #[]= method in Enumerable? What method would it
require the class to have?  How would you even implement #[]= for a
file, IO, or Socket?

Sam