From: Ross Bamford <rossrt@...>
Date: 2006-03-21T19:08:54+09:00
Subject: Re: iterate chars in a string

On Tue, 2006-03-21 at 18:47 +0900, Robert Dober wrote:
> Sorry Robert but I do not think I made myself too clear
> 
> we now about each_byte and I already combined your #chr and String#each_byte
> 
> so we had already established
> 
> "Ty Mr. Klemme".each_byte {  |b| puts b.chr }
> 
> which is pretty elegant, don't you agree?
> So Enumerators are not needed.
> 

Duck typing?

require 'enumerator'

def just_iterate(obj)
  obj.each { |e| p e }
end

just_iterate("abc")
# (prints) "abc"

just_iterate("abc".enum_for(:each_byte))
# (prints) 97
#          98
#          99

> Now after that we switched discussing the behaviour of String#each and I
> *really* feal that String#each should us give that kind of behaviour.
> As I see that a lot of people think that the current behaviour of
> String#each is a good one, and changing it would not be an option anyway I
> thaught that the only solution would be to enhance the behaviour of
> String#each.
> The idea for that behaviour comes from Ruby itself (look at IO#gets)
> 
> then
> 
>    "Ty Mr. Klemme".each_byte {  |b| puts b.chr }
> 
> would be the same as
> 
>     "Ty Mr. Klemme".each( 1 ) {  |b| puts b }
> 
> There is always more than one way to do it ;)

Umm, there's *already* more than one way to do it :) But Enumerator
really is a very useful class:

"abc\ndef\nghi\njkl".each { |e| p e }
# "abc\n"
# "def\n"
# "ghi\n"
# "jkl"

"abc\ndef\nghi\njkl\n".enum_for(:each_byte).each { |e| p e.chr }
# "a"
# "b"
# "c"
# "\n"
# "d"
# "e"
# etc.

"abc\ndef\nghi\njkl\n".enum_slice(2).each { |e| p e }
# ["abc\n", "def\n"]
# ["ghi\n", "jkl\n"]

"abc\ndef\nghi\njkl\n".enum_for(:each_byte).enum_slice(2).each { |e| p e }
# [97, 98]
# [99, 10]
# [100, 101]

And crucially:

"abc\ndef\nghi\njkl\n".enum_for(:each_byte).enum_slice(2).map do |(a,b)|
  (a + b).chr
end
# => ["\303", "m", "\311", "p", "\317", "s", "\325", "v"]

How would map and other Enumerable methods work if 'each' needed
arguments?

-- 
Ross Bamford - rosco@roscopeco.REMOVE.co.uk